Android

有时候在开发中会遇到一些“诡异”的要求，比如在ViewPager中嵌入ListView，或者再嵌入一个ViewPager，那么在滑动的时候就会造成被嵌入的XXView不能滑动了，那么现在就把最外层的ViewPager禁止滑动吧，让被嵌入的XXView获得滑动事件好了。关于解决方法，网上也有很多说法，基本上是一致的，但是需要理解这个[Android](http://lib.csdn.net/base/15)下的事件分发机制才行，不明白事件分发机制的，上网查些资料看看，然后我这里也有简单的介绍，请参看博客Android自定义控件——侧滑菜单的下方。 怎样禁止ViewPager左右滑动呢？大致就是重写ViewPager，覆盖ViewPager的onInterceptTouchEvent(MotionEvent arg0)方法和onTouchEvent(MotionEvent arg0)方法，这两个方法的返回值都是boolean类型的，只需要将返回值改为false，那么ViewPager就不会消耗掉手指滑动的事件了，转而传递给上层View去处理或者该事件就直接终止了。下面是我的自定义ViewPager。 ``` `<span class=“hljs-keyword”>public</span> <span class=“hljs-class”><span class=“hljs-keyword”>class</span> <span class=“hljs-title”>NoScrollViewPager</span> <span class=“hljs-keyword”>extends</span> <span class=“hljs-title”>ViewPager</span> {</span> <span class=“hljs-keyword”>private</span> <span class=“hljs-keyword”>boolean</span> noScroll = <span class=“hljs-keyword”>false</span>; &lt;span class="hljs-keyword">public&lt;/span> &lt;span class="hljs-title">NoScrollViewPager&lt;/span>(Context context, AttributeSet attrs) { &lt;span class="hljs-keyword">super&lt;/span>(context, attrs); &lt;span class="hljs-comment">// TODO Auto-generated constructor stub&lt;/span> } &lt;span class="hljs-keyword">public&lt;/span> &lt;span class="hljs-title">NoScrollViewPager&lt;/span>(Context context) { &lt;span class="hljs-keyword">super&lt;/span>(context); } &lt;span class="hljs-keyword">public&lt;/span> &lt;span class="hljs-keyword">void&lt;/span> &lt;span class="hljs-title">setNoScroll&lt;/span>(&lt;span class="hljs-keyword">boolean&lt;/span> noScroll) { &lt;span class="hljs-keyword">this&lt;/span>.noScroll = noScroll; } &lt;span class="hljs-annotation">@Override&lt;/span> &lt;span class="hljs-keyword">public&lt;/span> &lt;span class="hljs-keyword">void&lt;/span> &lt;span class="hljs-title">scrollTo&lt;/span>(&lt;span class="hljs-keyword">int&lt;/span> x, &lt;span class="hljs-keyword">int&lt;/span> y) { &lt;span class="hljs-keyword">super&lt;/span>.scrollTo(x, y); } &lt;span class="hljs-annotation">@Override&lt;/span> &lt;span class="hljs-keyword">public&lt;/span> &lt;span class="hljs-keyword">boolean&lt;/span> &lt;span class="hljs-title">onTouchEvent&lt;/span>(MotionEvent arg0) { &lt;span class="hljs-comment">/* return false;//super.onTouchEvent(arg0); */&lt;/span> &lt;span class="hljs-keyword">if&lt;/span> (noScroll) &lt;span class="hljs-keyword">return&lt;/span> &lt;span class="hljs-keyword">false&lt;/span>; &lt;span class="hljs-keyword">else&lt;/span> &lt;span class="hljs-keyword">return&lt;/span> &lt;span class="hljs-keyword">super&lt;/span>.onTouchEvent(arg0); } &lt;span class="hljs-annotation">@Override&lt;/span> &lt;span class="hljs-keyword">public&lt;/span> &lt;span class="hljs-keyword">boolean&lt;/span> &lt;span class="hljs-title">onInterceptTouchEvent&lt;/span>(MotionEvent arg0) { &lt;span class="hljs-keyword">if&lt;/span> (noScroll) &lt;span class="hljs-keyword">return&lt;/span> &lt;span class="hljs-keyword">false&lt;/span>; &lt;span class="hljs-keyword">else&lt;/span> &lt;span class="hljs-keyword">return&lt;/span> &lt;span class="hljs-keyword">super&lt;/span>.onInterceptTouchEvent(arg0); } &lt;span class="hljs-annotation">@Override&lt;/span> &lt;span class="hljs-keyword">public&lt;/span> &lt;span class="hljs-keyword">void&lt;/span> &lt;span class="hljs-title">setCurrentItem&lt;/span>(&lt;span class="hljs-keyword">int&lt;/span> item, &lt;span class="hljs-keyword">boolean&lt;/span> smoothScroll) { &lt;span class="hljs-keyword">super&lt;/span>.setCurrentItem(item, smoothScroll); } &lt;span class="hljs-annotation">@Override&lt;/span> &lt;span class="hljs-keyword">public&lt;/span> &lt;span class="hljs-keyword">void&lt;/span> &lt;span class="hljs-title">setCurrentItem&lt;/span>(&lt;span class="hljs-keyword">int&lt;/span> item) { &lt;span class="hljs-keyword">super&lt;/span>.setCurrentItem(item); } }` ...

查询了google发现在android一下有几种方法可以做到，但是经过实际测试发现下面这种方法是最准确的 Rect bounds = new Rect(); String text = "Hello World"; TextPaint paint; paint = findViewById(R.id.hello_world).getPaint(); paint.getTextBounds(text, 0, text.length(), bounds); int width = bounds.width(); ``` Paint pFont = new Paint(); Rect rect = new Rect(); pFont.getTextBounds("豆", 0, 1, rect); Log.v(TAG, "height:"+rect.height()+"width:"+rect.width()); ## Android_FontMetrics对象的各种基准线(以及怎么获取文字的width和height) </div> Canvas 作为绘制文本时，使用FontMetrics对象，计算位置的坐标。 public static class FontMetrics { /** * The maximum distance above the baseline for the tallest glyph in * the font at a given text size. / public float top; /* * The recommended distance above the baseline for singled spaced text. / public float ascent; /* * The recommended distance below the baseline for singled spaced text. / public float descent; /* * The maximum distance below the baseline for the lowest glyph in * the font at a given text size. / public float bottom; /* * The recommended additional space to add between lines of text. */ public float leading; } ...

//判断android 版本然后设置Systembar颜色-设置透明 public void initSystemBar() { Window window = getWindow(); //4.4版本及以上 if (Build.VERSION.SDK_INT &gt;= Build.VERSION_CODES.KITKAT) { window.setFlags( WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS, WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS); } //5.0版本及以上 if (Build.VERSION.SDK_INT &gt;= Build.VERSION_CODES.LOLLIPOP) { window.clearFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS | WindowManager.LayoutParams.FLAG_TRANSLUCENT_NAVIGATION); window.getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN | View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION | View.SYSTEM_UI_FLAG_LAYOUT_STABLE); window.addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS); window.setStatusBarColor(Color.TRANSPARENT); } }

The user guide for this mirror Powered by Tencent Bugly (bugly.qq.com) - [ANDROID SDK](http://android-mirror.bugly.qq.com:8080/include/usage.html#androidsdk) - [Android Studio](http://android-mirror.bugly.qq.com:8080/include/usage.html#ASD) <div class="tab-content"> <div id="androidsdk" class="tab active"> <span class="subtitle">☀ Windows</span> <span class="content">**A. 打开Android SDK Manager**</span> <span class="content">**B. 设置代理**</span> <span class="content">请务必选择: Force https://&#8230; sources to be fetched using http://&#8230;</span> <span class="content">**C. 检查代理是否正常工作**</span> <span class="content">点击菜单Package>Reload，如果能获取新版本，表明可以正常访问镜像</span> <span class="content">**D. 选择包进行安装**</span> <span class="subtitle">☀ Mac</span> <span class="content">**A. Terminal下，cd到android sdk部署目录**</span> ...

http://blog.csdn.net/sunyubo458/article/details/6680840 作为程序员，了解diff&patch命 令是非常必要的。比如说我们发现某个项目有bug代码，而自己又没有svn的提交权限，那么此时最合适的解决方法就是用diff命令做一个补丁发给项目成 员。项目成员通过patch命令可以立刻知道你的意图。有人会说直接传一个新文件不是更简单？不要忘了，一个patch文件尺寸更小传输更快，而且可以明 显的看到都做了哪些修改。 保证当前目录是demo名录： # mkdir demo # cd demo 先模拟一个项目目录old： # mkdir -p old/a/b # vi old/a/b/foo.txt old_line_1 old_line_2 假设我们发现项目old有bug代码，下面我们先拷贝一个新目录new，并在此修改bug代码： # cp -r old new # vi new/a/b/foo.txt new_line_1 new_line_2 保证old和new两个目录都在当前目录下，下面就可以使用diff命令了，不要使用绝对路径，而应该使用相对路径，至于原因，看到文章结尾你就清楚了： # LC_ALL=C TZ=UTC0 diff -Naur old new > foo.patch 如果不在意字符集，时差等问题，也可以省略LC_ALL=C TZ=UTC0环境变量： # diff -Naur old new > foo.patch 其中-Naur参数属于固定打法，不管是对一个文件，还是对一个目录，在使用这个参数基本就可以了。 大概浏览一下补丁文件： # cat foo.patch diff -Naur old/a/b/foo.txt new/a/b/foo.txt — old/a/b/foo.txt 2009-12-07 20:40:07.000000000 +0800 +++ new/a/b/foo.txt 2009-12-07 20:41:51.000000000 +0800 @@ -1,2 +1,2 @@ -old_line_1 -old_line_2 +new_line_1 +new_line_2 ...

转自：http://www.jianshu.com/p/2a7d16ab29e8 本教程采用阿里dexposed开源库实现。 https://github.com/alibaba/dexposed </blockquote> ## 主APP实现： ### 主程序Application onCreate方法中初始化dexposed ``` &lt;span class="hljs-tag">DexposedBridge&lt;/span>&lt;span class="hljs-class">.canDexposed&lt;/span>(&lt;span class="hljs-tag">context&lt;/span>); ### Patch apk下载及修复： - 为保证修复patch的及时性，使用push推送patch，客户端收到消息后立即完成patch的下载及修复； - 客户端版本管理模块在程序入口Activity中检测是否有需要修复的patch； - 下载完patch apk到程序私有目录，即/data/data/packageName/files目录，同时可在xml中保存patch apk本地存储路径、方便下载启动app时加载补丁patch。 ``` ` &lt;span class="hljs-keyword">public&lt;/span> &lt;span class="hljs-class">&lt;span class="hljs-keyword">class&lt;/span> &lt;span class="hljs-title">HotPatchManager&lt;/span> &lt;/span>{ &lt;span class="hljs-keyword">public&lt;/span> &lt;span class="hljs-keyword">static&lt;/span> &lt;span class="hljs-keyword">boolean&lt;/span> canDexposed = &lt;span class="hljs-keyword">false&lt;/span>; &lt;span class="hljs-keyword">private&lt;/span> &lt;span class="hljs-keyword">static&lt;/span> &lt;span class="hljs-keyword">final&lt;/span> String SP_KEY_HOT_PATCH = &lt;span class="hljs-string">"hot_patch_path"&lt;/span>; &lt;span class="hljs-comment">/** * init hotPatch library. * * &lt;span class="hljs-doctag">@param&lt;/span> context */&lt;/span> &lt;span class="hljs-function">&lt;span class="hljs-keyword">public&lt;/span> &lt;span class="hljs-keyword">static&lt;/span> &lt;span class="hljs-keyword">void&lt;/span> &lt;span class="hljs-title">init&lt;/span>&lt;span class="hljs-params">(Context context)&lt;/span> &lt;/span>{ &lt;span class="hljs-comment">// aop init.&lt;/span> canDexposed = DexposedBridge.canDexposed(context); &lt;span class="hljs-keyword">if&lt;/span> (canDexposed) { List&lt;String&gt; list = getHotPatchPaths(context); &lt;span class="hljs-keyword">if&lt;/span> (list != &lt;span class="hljs-keyword">null&lt;/span> && list.size() &gt; &lt;span class="hljs-number">0&lt;/span>) { &lt;span class="hljs-keyword">for&lt;/span> (String path : list) { runPatchApk(context, path); } } } &lt;span class="hljs-keyword">else&lt;/span> { &lt;span class="hljs-keyword">if&lt;/span> (LogUtils.DEBUG) { LogUtils.d(&lt;span class="hljs-string">"==========your device not support dexposed aop.=========="&lt;/span>); } } } &lt;span class="hljs-comment">/** * /data/data/package/files * * &lt;span class="hljs-doctag">@param&lt;/span> context * &lt;span class="hljs-doctag">@param&lt;/span> apkPath */&lt;/span> &lt;span class="hljs-function">&lt;span class="hljs-keyword">public&lt;/span> &lt;span class="hljs-keyword">static&lt;/span> &lt;span class="hljs-keyword">void&lt;/span> &lt;span class="hljs-title">runPatchApk&lt;/span>&lt;span class="hljs-params">(Context context, String apkPath)&lt;/span> &lt;/span>{ &lt;span class="hljs-keyword">if&lt;/span> (Build.VERSION.SDK_INT &gt;= &lt;span class="hljs-number">21&lt;/span> || !canDexposed) { LogUtils.d(&lt;span class="hljs-string">"This device doesn't support dexposed."&lt;/span>); &lt;span class="hljs-keyword">return&lt;/span>; } &lt;span class="hljs-keyword">if&lt;/span> (!pathIsValid(context, apkPath)) { &lt;span class="hljs-keyword">return&lt;/span>; } &lt;span class="hljs-keyword">try&lt;/span> { PatchResult result = PatchMain.load(context, apkPath, &lt;span class="hljs-keyword">null&lt;/span>); &lt;span class="hljs-keyword">if&lt;/span> (result.isSuccess()) { LogUtils.d(&lt;span class="hljs-string">"hotPath load apk success."&lt;/span>); } &lt;span class="hljs-keyword">else&lt;/span> { LogUtils.e(&lt;span class="hljs-string">"hotPath load apk error."&lt;/span>, result.getErrorInfo()); result.getThrowbale().printStackTrace(); } } &lt;span class="hljs-keyword">catch&lt;/span> (Exception e) { e.printStackTrace(); } } &lt;span class="hljs-comment">/** * download hotPatch and auto mege. * * &lt;span class="hljs-doctag">@param&lt;/span> context */&lt;/span> &lt;span class="hljs-function">&lt;span class="hljs-keyword">public&lt;/span> &lt;span class="hljs-keyword">static&lt;/span> &lt;span class="hljs-keyword">void&lt;/span> &lt;span class="hljs-title">downloadHotPatch&lt;/span>&lt;span class="hljs-params">(&lt;span class="hljs-keyword">final&lt;/span> Context context, String downloadUrl)&lt;/span> &lt;/span>{ &lt;span class="hljs-keyword">if&lt;/span> (TextUtils.isEmpty(downloadUrl)) { LogUtils.d(&lt;span class="hljs-string">"downloadUrl is null."&lt;/span>); &lt;span class="hljs-keyword">return&lt;/span>; } DownloadInfo downloadInfo = &lt;span class="hljs-keyword">new&lt;/span> DownloadInfo(); downloadInfo.setDownloadUrl(downloadUrl); String fileName = downloadUrl.substring(downloadUrl.lastIndexOf(&lt;span class="hljs-string">"/"&lt;/span>) + &lt;span class="hljs-number">1&lt;/span>); String fileSavePath = &lt;span class="hljs-keyword">new&lt;/span> File(context.getFilesDir(), fileName).getAbsolutePath(); downloadInfo.setFileSavePath(fileSavePath); downloadInfo.setDaoCallback( &lt;span class="hljs-keyword">new&lt;/span> Task.Callback() { &lt;span class="hljs-annotation">@Override&lt;/span> &lt;span class="hljs-function">&lt;span class="hljs-keyword">public&lt;/span> &lt;span class="hljs-keyword">void&lt;/span> &lt;span class="hljs-title">onSuccess&lt;/span>&lt;span class="hljs-params">(DownloadInfo downloadInfo)&lt;/span> &lt;/span>{ LogUtils.d(&lt;span class="hljs-string">"runPatchApk begin."&lt;/span>, downloadInfo.getFileSavePath()); runPatchApk(context, downloadInfo.getFileSavePath()); appendHotPatchPath(context, downloadInfo.getFileSavePath()); LogUtils.d(&lt;span class="hljs-string">"runPatchApk end."&lt;/span>, downloadInfo.getFileSavePath()); } &lt;span class="hljs-annotation">@Override&lt;/span> &lt;span class="hljs-function">&lt;span class="hljs-keyword">public&lt;/span> &lt;span class="hljs-keyword">void&lt;/span> &lt;span class="hljs-title">onStart&lt;/span>&lt;span class="hljs-params">(DownloadInfo downloadInfo)&lt;/span> &lt;/span>{ } &lt;span class="hljs-annotation">@Override&lt;/span> &lt;span class="hljs-function">&lt;span class="hljs-keyword">public&lt;/span> &lt;span class="hljs-keyword">void&lt;/span> &lt;span class="hljs-title">onFailure&lt;/span>&lt;span class="hljs-params">(DownloadInfo downloadInfo)&lt;/span> &lt;/span>{ } &lt;span class="hljs-annotation">@Override&lt;/span> &lt;span class="hljs-function">&lt;span class="hljs-keyword">public&lt;/span> &lt;span class="hljs-keyword">boolean&lt;/span> &lt;span class="hljs-title">onLoading&lt;/span>&lt;span class="hljs-params">(&lt;span class="hljs-keyword">long&lt;/span> total, &lt;span class="hljs-keyword">long&lt;/span> current)&lt;/span> &lt;/span>{ &lt;span class="hljs-keyword">return&lt;/span> &lt;span class="hljs-keyword">true&lt;/span>; } &lt;span class="hljs-annotation">@Override&lt;/span> &lt;span class="hljs-function">&lt;span class="hljs-keyword">public&lt;/span> &lt;span class="hljs-keyword">void&lt;/span> &lt;span class="hljs-title">onCancelled&lt;/span>&lt;span class="hljs-params">(DownloadInfo downloadInfo)&lt;/span> &lt;/span>{ } } ); DownloadManager dm = DownloadService.getDownloadManager(context, DownloadService.ACTION); dm.addDownloadTask(downloadInfo); } &lt;span class="hljs-function">&lt;span class="hljs-keyword">public&lt;/span> &lt;span class="hljs-keyword">static&lt;/span> &lt;span class="hljs-keyword">void&lt;/span> &lt;span class="hljs-title">clearHotPatchFiles&lt;/span>&lt;span class="hljs-params">(Context context)&lt;/span> &lt;/span>{ List&lt;String&gt; list = getHotPatchPaths(context); &lt;span class="hljs-keyword">if&lt;/span> (list != &lt;span class="hljs-keyword">null&lt;/span> && list.size() &gt; &lt;span class="hljs-number">0&lt;/span>) { &lt;span class="hljs-keyword">for&lt;/span> (String path : list) { FileUtils.delFile(path); } } } &lt;span class="hljs-function">&lt;span class="hljs-keyword">public&lt;/span> &lt;span class="hljs-keyword">static&lt;/span> &lt;span class="hljs-keyword">boolean&lt;/span> &lt;span class="hljs-title">pathIsValid&lt;/span>&lt;span class="hljs-params">(Context context, String apkPath)&lt;/span> &lt;/span>{ &lt;span class="hljs-keyword">if&lt;/span> (TextUtils.isEmpty(apkPath)) { LogUtils.d(&lt;span class="hljs-string">"apkPath is null."&lt;/span>); &lt;span class="hljs-keyword">return&lt;/span> &lt;span class="hljs-keyword">false&lt;/span>; } String parentDir = String.format(&lt;span class="hljs-string">"/data/data/%s/files"&lt;/span>, context.getPackageName()); File apkFile = &lt;span class="hljs-keyword">new&lt;/span> File(apkPath); &lt;span class="hljs-keyword">if&lt;/span> (!parentDir.equals(apkFile.getParent())) { LogUtils.d(&lt;span class="hljs-string">"apkPath is error."&lt;/span>, apkPath); &lt;span class="hljs-keyword">return&lt;/span> &lt;span class="hljs-keyword">false&lt;/span>; } &lt;span class="hljs-keyword">if&lt;/span> (!apkFile.exists()){ LogUtils.d(&lt;span class="hljs-string">"apkPath is not exist."&lt;/span>, apkPath); &lt;span class="hljs-keyword">return&lt;/span> &lt;span class="hljs-keyword">false&lt;/span>; } &lt;span class="hljs-keyword">return&lt;/span> &lt;span class="hljs-keyword">true&lt;/span>; } &lt;span class="hljs-function">&lt;span class="hljs-keyword">public&lt;/span> &lt;span class="hljs-keyword">static&lt;/span> List&lt;String&gt; &lt;span class="hljs-title">getHotPatchPaths&lt;/span>&lt;span class="hljs-params">(Context context)&lt;/span> &lt;/span>{ List&lt;String&gt; list = &lt;span class="hljs-keyword">null&lt;/span>; SP sp = SP.getInstance(context); String paths = sp.getString(SP_KEY_HOT_PATCH, &lt;span class="hljs-keyword">null&lt;/span>); &lt;span class="hljs-keyword">if&lt;/span> (!TextUtils.isEmpty(paths)) { &lt;span class="hljs-keyword">if&lt;/span> (paths.indexOf(&lt;span class="hljs-string">","&lt;/span>) != -&lt;span class="hljs-number">1&lt;/span>) { String[] pathArr = paths.split(&lt;span class="hljs-string">","&lt;/span>); &lt;span class="hljs-keyword">if&lt;/span> (pathArr != &lt;span class="hljs-keyword">null&lt;/span> && pathArr.length &gt; &lt;span class="hljs-number">0&lt;/span>) { list = Arrays.asList(paths); } } &lt;span class="hljs-keyword">else&lt;/span> { list = &lt;span class="hljs-keyword">new&lt;/span> ArrayList&lt;String&gt;(); list.add(paths); } } &lt;span class="hljs-keyword">return&lt;/span> list; } &lt;span class="hljs-function">&lt;span class="hljs-keyword">public&lt;/span> &lt;span class="hljs-keyword">static&lt;/span> &lt;span class="hljs-keyword">void&lt;/span> &lt;span class="hljs-title">appendHotPatchPath&lt;/span>&lt;span class="hljs-params">(Context context, String apkPath)&lt;/span> &lt;/span>{ &lt;span class="hljs-keyword">if&lt;/span> (!pathIsValid(context, apkPath)) { &lt;span class="hljs-keyword">return&lt;/span>; } SP sp = SP.getInstance(context); String paths = sp.getString(SP_KEY_HOT_PATCH, &lt;span class="hljs-keyword">null&lt;/span>); &lt;span class="hljs-keyword">if&lt;/span> (!TextUtils.isEmpty(paths)) { String allPath = &lt;span class="hljs-keyword">new&lt;/span> StringBuilder(apkPath).append(&lt;span class="hljs-string">","&lt;/span>).append(apkPath).toString(); sp.commit(SP_KEY_HOT_PATCH, allPath); } &lt;span class="hljs-keyword">else&lt;/span> { sp.commit(SP_KEY_HOT_PATCH, apkPath); } } &lt;span class="hljs-function">&lt;span class="hljs-keyword">public&lt;/span> &lt;span class="hljs-keyword">static&lt;/span> &lt;span class="hljs-keyword">void&lt;/span> &lt;span class="hljs-title">clearHotPatchPaths&lt;/span>&lt;span class="hljs-params">(Context context)&lt;/span> &lt;/span>{ SP sp = SP.getInstance(context); sp.commit(SP_KEY_HOT_PATCH, &lt;span class="hljs-string">""&lt;/span>); } }` ## Patch Apk部分： <blockquote> dexpose支持方法粒度的patch，可以实现整个方法的替换或方法前、后执行修复代码。 以下实例为方法替换实例，其它只需实现相应的回调接口即可。 ...

转载[http://blog.csdn.net/zhongkejingwang/article/details/38868463](http://blog.csdn.net/zhongkejingwang/article/details/38868463) 前面写过一篇关于下拉刷新控件的博客[下拉刷新控件终结者：PullToRefreshLayout](http://blog.csdn.net/zhongkejingwang/article/details/38340701)，后来看到好多人还有上拉加载更多的需求，于是就在前面下拉刷新控件的基础上进行了改进，加了上拉加载的功能。不仅如此，我已经把它改成了对所有View都通用！可以随心所欲使用这两个功能~~ 我做了一个大集合的demo，实现了ListView、GridView、ExpandableListView、ScrollView、WebView、ImageView、TextView的下拉刷新和上拉加载。后面会提供demo的下载地址。（csdn上的demo有小bug，最新代码已上传到github：[https://github.com/jingchenUSTC/PullToRefreshAndLoad](https://github.com/jingchenUSTC/PullToRefreshAndLoad)) 依照惯例，下面将会是一大波效果图： demo首页也是可下拉的ListView，在底下可以加入table：  ListView：  GridView：  ExpandableListView：  ScrollView：  WebView：  ImageView：  TextView：  很不错吧？最后的ImageView和TextView是最简单的，直接在下面的接口方法里返回true。 增加上拉加载很简单，和管理下拉头一样，再多管理一个上拉头，也不费事；至于把它改成通用的就需要统一一下View的行为了，为此，我定义了这样一个接口： <div class="dp-highlighter bg_java"> <div class="bar"> <div class="tools"> **[java]** [view plain](http://blog.csdn.net/zhongkejingwang/article/details/38868463#)<span class="tracking-ad" data-mod="popu_168"><span class="tracking-ad" data-mod="popu_168"> [copy](http://blog.csdn.net/zhongkejingwang/article/details/38868463#)</span></span> <div> <embed id="ZeroClipboardMovie_1" src="http://static.blog.csdn.net/scripts/ZeroClipboard/ZeroClipboard.swf" type="application/x-shockwave-flash" width="18" height="18" align="middle" name="ZeroClipboardMovie_1"> </embed> </div> </div> </div> - <span class="keyword">package</span> com.jingchen.pulltorefresh.pullableview; - - <span class="keyword">public</span> <span class="keyword">interface</span> Pullable - { - <span class="comment">/**</span> - <span class="comment"> * 判断是否可以下拉，如果不需要下拉功能可以直接return false</span> - <span class="comment"> * </span> - <span class="comment"> * @return true如果可以下拉否则返回false</span> - <span class="comment"> */</span> - <span class="keyword">boolean</span> canPullDown(); - - <span class="comment">/**</span> - <span class="comment"> * 判断是否可以上拉，如果不需要上拉功能可以直接return false</span> - <span class="comment"> * </span> - <span class="comment"> * @return true如果可以上拉否则返回false</span> - <span class="comment"> */</span> - <span class="keyword">boolean</span> canPullUp(); - } </div> 从接口名就可以看出它是一个提供判断是否可拉的方法的接口。这个接口的两个方法，canPullDown()是判断何时可以下拉的方法，canPullUp()则是判断何时可以上拉，我在demo中的判断是滑到顶部的时候可以下拉，滑到底部的时候可以上拉。所有需要上拉和下拉的View都需要实现这个接口。后面会给出一些View的实现。先来看看改进后的自定义的布局PullToRefreshLayout，增加了一个上拉头，下拉头和上拉头之间的View是实现了Pullable接口的pullableView。相比前面的版本，这里有改动的需要注意的地方如下：1、增加了上拉头，相应的也增加了控制变量。 2、拉动时消除content_view事件防止误触发不再使用反射，直接设置 event.setAction(MotionEvent.ACTION_CANCEL)。 3、消除了拉动过程中的多点触碰导致的剧变。 4、不再设置content_view的onTouListener，让使用者可以更加自由的设置监听器。 这个PullToRefreshLayout只负责管理三个控件，如果一个View需要有上拉下拉功能则只需实现接口就行了。下面看PullToRefreshLayout的代码，注释写了好多： <div class="dp-highlighter bg_java"> <div class="bar"> <div class="tools"> **[java]** [view plain](http://blog.csdn.net/zhongkejingwang/article/details/38868463#)<span class="tracking-ad" data-mod="popu_168"><span class="tracking-ad" data-mod="popu_168"> [copy](http://blog.csdn.net/zhongkejingwang/article/details/38868463#)</span></span> <div> <embed id="ZeroClipboardMovie_2" src="http://static.blog.csdn.net/scripts/ZeroClipboard/ZeroClipboard.swf" type="application/x-shockwave-flash" width="18" height="18" align="middle" name="ZeroClipboardMovie_2"> </embed> </div> </div> </div> - <span class="keyword">package</span> com.jingchen.pulltorefresh; - - <span class="keyword">import</span> java.util.Timer; - <span class="keyword">import</span> java.util.TimerTask; - - <span class="keyword">import</span> <a href=<span class="string">&#8220;http://lib.csdn.net/base/15&#8221;</span> <span class="keyword">class</span>=<span class="string">&#8220;replace_word&#8221;</span> title=<span class="string">&#8220;undefined&#8221;</span> target=<span class="string">&#8220;_blank&#8221;</span> style=<span class="string">&#8220;color:#df3434; font-weight:bold;&#8221;</span>>android</a>.content.Context; - <span class="keyword">import</span> android.graphics.Canvas; - <span class="keyword">import</span> android.graphics.LinearGradient; - <span class="keyword">import</span> android.graphics.Paint; - <span class="keyword">import</span> android.graphics.Paint.Style; - <span class="keyword">import</span> android.graphics.RectF; - <span class="keyword">import</span> android.graphics.Shader.TileMode; - <span class="keyword">import</span> android.os.Handler; - <span class="keyword">import</span> android.os.Message; - <span class="keyword">import</span> android.util.AttributeSet; - <span class="keyword">import</span> android.util.Log; - <span class="keyword">import</span> android.view.MotionEvent; - <span class="keyword">import</span> android.view.View; - <span class="keyword">import</span> android.view.ViewGroup; - <span class="keyword">import</span> android.view.animation.AnimationUtils; - <span class="keyword">import</span> android.view.animation.LinearInterpolator; - <span class="keyword">import</span> android.view.animation.RotateAnimation; - <span class="keyword">import</span> android.widget.RelativeLayout; - <span class="keyword">import</span> android.widget.TextView; - - <span class="keyword">import</span> com.jingchen.pulltorefresh.pullableview.Pullable; - - <span class="comment">/**</span> - <span class="comment"> * 自定义的布局，用来管理三个子控件，其中一个是下拉头，一个是包含内容的pullableView（可以是实现Pullable接口的的任何View），</span> - <span class="comment"> * 还有一个上拉头</span> - <span class="comment"> * </span> - <span class="comment"> * @author 陈靖</span> - <span class="comment"> */</span> - <span class="keyword">public</span> <span class="keyword">class</span> PullToRefreshLayout <span class="keyword">extends</span> RelativeLayout - { - <span class="keyword">public</span> <span class="keyword">static</span> <span class="keyword">final</span> String TAG = <span class="string">&#8220;PullToRefreshLayout&#8221;</span>; - <span class="comment">// 初始状态</span> - <span class="keyword">public</span> <span class="keyword">static</span> <span class="keyword">final</span> <span class="keyword">int</span> INIT = <span class="number"></span>; - <span class="comment">// 释放刷新</span> - <span class="keyword">public</span> <span class="keyword">static</span> <span class="keyword">final</span> <span class="keyword">int</span> RELEASE_TO_REFRESH = <span class="number">1</span>; - <span class="comment">// 正在刷新</span> - <span class="keyword">public</span> <span class="keyword">static</span> <span class="keyword">final</span> <span class="keyword">int</span> REFRESHING = <span class="number">2</span>; - <span class="comment">// 释放加载</span> - <span class="keyword">public</span> <span class="keyword">static</span> <span class="keyword">final</span> <span class="keyword">int</span> RELEASE_TO_LOAD = <span class="number">3</span>; - <span class="comment">// 正在加载</span> - <span class="keyword">public</span> <span class="keyword">static</span> <span class="keyword">final</span> <span class="keyword">int</span> LOADING = <span class="number">4</span>; - <span class="comment">// 操作完毕</span> - <span class="keyword">public</span> <span class="keyword">static</span> <span class="keyword">final</span> <span class="keyword">int</span> DONE = <span class="number">5</span>; - <span class="comment">// 当前状态</span> - <span class="keyword">private</span> <span class="keyword">int</span> state = INIT; - <span class="comment">// 刷新回调接口</span> - <span class="keyword">private</span> OnRefreshListener mListener; - <span class="comment">// 刷新成功</span> - <span class="keyword">public</span> <span class="keyword">static</span> <span class="keyword">final</span> <span class="keyword">int</span> SUCCEED = <span class="number"></span>; - <span class="comment">// 刷新失败</span> - <span class="keyword">public</span> <span class="keyword">static</span> <span class="keyword">final</span> <span class="keyword">int</span> FAIL = <span class="number">1</span>; - <span class="comment">// 按下Y坐标，上一个事件点Y坐标</span> - <span class="keyword">private</span> <span class="keyword">float</span> downY, lastY; - - <span class="comment">// 下拉的距离。注意：pullDownY和pullUpY不可能同时不为0</span> - <span class="keyword">public</span> <span class="keyword">float</span> pullDownY = <span class="number"></span>; - <span class="comment">// 上拉的距离</span> - <span class="keyword">private</span> <span class="keyword">float</span> pullUpY = <span class="number"></span>; - - <span class="comment">// 释放刷新的距离</span> - <span class="keyword">private</span> <span class="keyword">float</span> refreshDist = <span class="number">200</span>; - <span class="comment">// 释放加载的距离</span> - <span class="keyword">private</span> <span class="keyword">float</span> loadmoreDist = <span class="number">200</span>; - - <span class="keyword">private</span> MyTimer timer; - <span class="comment">// 回滚速度</span> - <span class="keyword">public</span> <span class="keyword">float</span> MOVE_SPEED = <span class="number">8</span>; - <span class="comment">// 第一次执行布局</span> - <span class="keyword">private</span> <span class="keyword">boolean</span> isLayout = <span class="keyword">false</span>; - <span class="comment">// 在刷新过程中滑动操作</span> - <span class="keyword">private</span> <span class="keyword">boolean</span> isTouch = <span class="keyword">false</span>; - <span class="comment">// 手指滑动距离与下拉头的滑动距离比，中间会随正切函数变化</span> - <span class="keyword">private</span> <span class="keyword">float</span> radio = <span class="number">2</span>; - - <span class="comment">// 下拉箭头的转180°动画</span> - <span class="keyword">private</span> RotateAnimation rotateAnimation; - <span class="comment">// 均匀旋转动画</span> - <span class="keyword">private</span> RotateAnimation refreshingAnimation; - - <span class="comment">// 下拉头</span> - <span class="keyword">private</span> View refreshView; - <span class="comment">// 下拉的箭头</span> - <span class="keyword">private</span> View pullView; - <span class="comment">// 正在刷新的图标</span> - <span class="keyword">private</span> View refreshingView; - <span class="comment">// 刷新结果图标</span> - <span class="keyword">private</span> View refreshStateImageView; - <span class="comment">// 刷新结果：成功或失败</span> - <span class="keyword">private</span> TextView refreshStateTextView; - - <span class="comment">// 上拉头</span> - <span class="keyword">private</span> View loadmoreView; - <span class="comment">// 上拉的箭头</span> - <span class="keyword">private</span> View pullUpView; - <span class="comment">// 正在加载的图标</span> - <span class="keyword">private</span> View loadingView; - <span class="comment">// 加载结果图标</span> - <span class="keyword">private</span> View loadStateImageView; - <span class="comment">// 加载结果：成功或失败</span> - <span class="keyword">private</span> TextView loadStateTextView; - - <span class="comment">// 实现了Pullable接口的View</span> - <span class="keyword">private</span> View pullableView; - <span class="comment">// 过滤多点触碰</span> - <span class="keyword">private</span> <span class="keyword">int</span> mEvents; - <span class="comment">// 这两个变量用来控制pull的方向，如果不加控制，当情况满足可上拉又可下拉时没法下拉</span> - <span class="keyword">private</span> <span class="keyword">boolean</span> canPullDown = <span class="keyword">true</span>; - <span class="keyword">private</span> <span class="keyword">boolean</span> canPullUp = <span class="keyword">true</span>; - - <span class="comment">/**</span> - <span class="comment"> * 执行自动回滚的handler</span> - <span class="comment"> */</span> - Handler updateHandler = <span class="keyword">new</span> Handler() - { - - <span class="annotation">@Override</span> - <span class="keyword">public</span> <span class="keyword">void</span> handleMessage(Message msg) - { - <span class="comment">// 回弹速度随下拉距离moveDeltaY增大而增大</span> - MOVE_SPEED = (<span class="keyword">float</span>) (<span class="number">8</span> + <span class="number">5</span> * Math.tan(Math.PI / <span class="number">2</span> - / getMeasuredHeight() * (pullDownY + Math.abs(pullUpY)))); - <span class="keyword">if</span> (!isTouch) - { - <span class="comment">// 正在刷新，且没有往上推的话则悬停，显示&#8221;正在刷新&#8230;&#8221;</span> - <span class="keyword">if</span> (state == REFRESHING && pullDownY <= refreshDist) - { - pullDownY = refreshDist; - timer.cancel(); - } <span class="keyword">else</span> <span class="keyword">if</span> (state == LOADING && -pullUpY <= loadmoreDist) - { - pullUpY = -loadmoreDist; - timer.cancel(); - } - - } - <span class="keyword">if</span> (pullDownY > <span class="number"></span>) - pullDownY -= MOVE_SPEED; - <span class="keyword">else</span> <span class="keyword">if</span> (pullUpY < <span class="number"></span>) - pullUpY += MOVE_SPEED; - <span class="keyword">if</span> (pullDownY < <span class="number"></span>) - { - <span class="comment">// 已完成回弹</span> - pullDownY = <span class="number"></span>; - pullView.clearAnimation(); - <span class="comment">// 隐藏下拉头时有可能还在刷新，只有当前状态不是正在刷新时才改变状态</span> - <span class="keyword">if</span> (state != REFRESHING && state != LOADING) - changeState(INIT); - timer.cancel(); - } - <span class="keyword">if</span> (pullUpY > <span class="number"></span>) - { - <span class="comment">// 已完成回弹</span> - pullUpY = <span class="number"></span>; - pullUpView.clearAnimation(); - <span class="comment">// 隐藏下拉头时有可能还在刷新，只有当前状态不是正在刷新时才改变状态</span> - <span class="keyword">if</span> (state != REFRESHING && state != LOADING) - changeState(INIT); - timer.cancel(); - } - <span class="comment">// 刷新布局,会自动调用onLayout</span> - requestLayout(); - } - - }; - - <span class="keyword">public</span> <span class="keyword">void</span> setOnRefreshListener(OnRefreshListener listener) - { - mListener = listener; - } - - <span class="keyword">public</span> PullToRefreshLayout(Context context) - { - <span class="keyword">super</span>(context); - initView(context); - } - - <span class="keyword">public</span> PullToRefreshLayout(Context context, AttributeSet attrs) - { - <span class="keyword">super</span>(context, attrs); - initView(context); - } - - <span class="keyword">public</span> PullToRefreshLayout(Context context, AttributeSet attrs, <span class="keyword">int</span> defStyle) - { - <span class="keyword">super</span>(context, attrs, defStyle); - initView(context); - } - - <span class="keyword">private</span> <span class="keyword">void</span> initView(Context context) - { - timer = <span class="keyword">new</span> MyTimer(updateHandler); - rotateAnimation = (RotateAnimation) AnimationUtils.loadAnimation( - context, R.anim.reverse_anim); - refreshingAnimation = (RotateAnimation) AnimationUtils.loadAnimation( - context, R.anim.rotating); - <span class="comment">// 添加匀速转动动画</span> - LinearInterpolator lir = <span class="keyword">new</span> LinearInterpolator(); - rotateAnimation.setInterpolator(lir); - refreshingAnimation.setInterpolator(lir); - } - - <span class="keyword">private</span> <span class="keyword">void</span> hide() - { - timer.schedule(<span class="number">5</span>); - } - - <span class="comment">/**</span> - <span class="comment"> * 完成刷新操作，显示刷新结果。注意：刷新完成后一定要调用这个方法</span> - <span class="comment"> */</span> - <span class="comment">/**</span> - <span class="comment"> * @param refreshResult</span> - <span class="comment"> * PullToRefreshLayout.SUCCEED代表成功，PullToRefreshLayout.FAIL代表失败</span> - <span class="comment"> */</span> - <span class="keyword">public</span> <span class="keyword">void</span> refreshFinish(<span class="keyword">int</span> refreshResult) - { - refreshingView.clearAnimation(); - refreshingView.setVisibility(View.GONE); - <span class="keyword">switch</span> (refreshResult) - { - <span class="keyword">case</span> SUCCEED: - <span class="comment">// 刷新成功</span> - refreshStateImageView.setVisibility(View.VISIBLE); - refreshStateTextView.setText(R.string.refresh_succeed); - refreshStateImageView - .setBackgroundResource(R.drawable.refresh_succeed); - <span class="keyword">break</span>; - <span class="keyword">case</span> FAIL: - <span class="keyword">default</span>: - <span class="comment">// 刷新失败</span> - refreshStateImageView.setVisibility(View.VISIBLE); - refreshStateTextView.setText(R.string.refresh_fail); - refreshStateImageView - .setBackgroundResource(R.drawable.refresh_failed); - <span class="keyword">break</span>; - } - <span class="comment">// 刷新结果停留1秒</span> - <span class="keyword">new</span> Handler() - { - <span class="annotation">@Override</span> - <span class="keyword">public</span> <span class="keyword">void</span> handleMessage(Message msg) - { - changeState(DONE); - hide(); - } - }.sendEmptyMessageDelayed(<span class="number"></span>, <span class="number">1000</span>); - } - - <span class="comment">/**</span> - <span class="comment"> * 加载完毕，显示加载结果。注意：加载完成后一定要调用这个方法</span> - <span class="comment"> * </span> - <span class="comment"> * @param refreshResult</span> - <span class="comment"> * PullToRefreshLayout.SUCCEED代表成功，PullToRefreshLayout.FAIL代表失败</span> - <span class="comment"> */</span> - <span class="keyword">public</span> <span class="keyword">void</span> loadmoreFinish(<span class="keyword">int</span> refreshResult) - { - loadingView.clearAnimation(); - loadingView.setVisibility(View.GONE); - <span class="keyword">switch</span> (refreshResult) - { - <span class="keyword">case</span> SUCCEED: - <span class="comment">// 加载成功</span> - loadStateImageView.setVisibility(View.VISIBLE); - loadStateTextView.setText(R.string.load_succeed); - loadStateImageView.setBackgroundResource(R.drawable.load_succeed); - <span class="keyword">break</span>; - <span class="keyword">case</span> FAIL: - <span class="keyword">default</span>: - <span class="comment">// 加载失败</span> - loadStateImageView.setVisibility(View.VISIBLE); - loadStateTextView.setText(R.string.load_fail); - loadStateImageView.setBackgroundResource(R.drawable.load_failed); - <span class="keyword">break</span>; - } - <span class="comment">// 刷新结果停留1秒</span> - <span class="keyword">new</span> Handler() - { - <span class="annotation">@Override</span> - <span class="keyword">public</span> <span class="keyword">void</span> handleMessage(Message msg) - { - changeState(DONE); - hide(); - } - }.sendEmptyMessageDelayed(<span class="number"></span>, <span class="number">1000</span>); - } - - <span class="keyword">private</span> <span class="keyword">void</span> changeState(<span class="keyword">int</span> to) - { - state = to; - <span class="keyword">switch</span> (state) - { - <span class="keyword">case</span> INIT: - <span class="comment">// 下拉布局初始状态</span> - refreshStateImageView.setVisibility(View.GONE); - refreshStateTextView.setText(R.string.pull_to_refresh); - pullView.clearAnimation(); - pullView.setVisibility(View.VISIBLE); - <span class="comment">// 上拉布局初始状态</span> - loadStateImageView.setVisibility(View.GONE); - loadStateTextView.setText(R.string.pullup_to_load); - pullUpView.clearAnimation(); - pullUpView.setVisibility(View.VISIBLE); - <span class="keyword">break</span>; - <span class="keyword">case</span> RELEASE_TO_REFRESH: - <span class="comment">// 释放刷新状态</span> - refreshStateTextView.setText(R.string.release_to_refresh); - pullView.startAnimation(rotateAnimation); - <span class="keyword">break</span>; - <span class="keyword">case</span> REFRESHING: - <span class="comment">// 正在刷新状态</span> - pullView.clearAnimation(); - refreshingView.setVisibility(View.VISIBLE); - pullView.setVisibility(View.INVISIBLE); - refreshingView.startAnimation(refreshingAnimation); - refreshStateTextView.setText(R.string.refreshing); - <span class="keyword">break</span>; - <span class="keyword">case</span> RELEASE_TO_LOAD: - <span class="comment">// 释放加载状态</span> - loadStateTextView.setText(R.string.release_to_load); - pullUpView.startAnimation(rotateAnimation); - <span class="keyword">break</span>; - <span class="keyword">case</span> LOADING: - <span class="comment">// 正在加载状态</span> - pullUpView.clearAnimation(); - loadingView.setVisibility(View.VISIBLE); - pullUpView.setVisibility(View.INVISIBLE); - loadingView.startAnimation(refreshingAnimation); - loadStateTextView.setText(R.string.loading); - <span class="keyword">break</span>; - <span class="keyword">case</span> DONE: - <span class="comment">// 刷新或加载完毕，啥都不做</span> - <span class="keyword">break</span>; - } - } - - <span class="comment">/**</span> - <span class="comment"> * 不限制上拉或下拉</span> - <span class="comment"> */</span> - <span class="keyword">private</span> <span class="keyword">void</span> releasePull() - { - canPullDown = <span class="keyword">true</span>; - canPullUp = <span class="keyword">true</span>; - } - - <span class="comment">/*</span> - <span class="comment"> * （非 Javadoc）由父控件决定是否分发事件，防止事件冲突</span> - <span class="comment"> * </span> - <span class="comment"> * @see android.view.ViewGroup#dispatchTouchEvent(android.view.MotionEvent)</span> - <span class="comment"> */</span> - <span class="annotation">@Override</span> - <span class="keyword">public</span> <span class="keyword">boolean</span> dispatchTouchEvent(MotionEvent ev) - { - <span class="keyword">switch</span> (ev.getActionMasked()) - { - <span class="keyword">case</span> MotionEvent.ACTION_DOWN: - downY = ev.getY(); - lastY = downY; - timer.cancel(); - mEvents = <span class="number"></span>; - releasePull(); - <span class="keyword">break</span>; - <span class="keyword">case</span> MotionEvent.ACTION_POINTER_DOWN: - <span class="keyword">case</span> MotionEvent.ACTION_POINTER_UP: - <span class="comment">// 过滤多点触碰</span> - <span class="keyword">break</span>; - <span class="keyword">case</span> MotionEvent.ACTION_MOVE: - <span class="keyword">if</span> (mEvents == <span class="number"></span>) - { - <span class="keyword">if</span> (((Pullable) pullableView).canPullDown() && canPullDown - && state != LOADING) - { - <span class="comment">// 可以下拉，正在加载时不能下拉</span> - <span class="comment">// 对实际滑动距离做缩小，造成用力拉的感觉</span> - <span class="keyword">if</span> (pullDownY < <span class="number"></span>) - { - pullDownY = <span class="number"></span>; - canPullDown = <span class="keyword">false</span>; - canPullUp = <span class="keyword">true</span>; - } - <span class="keyword">if</span> (pullDownY > getMeasuredHeight()) - pullDownY = getMeasuredHeight(); - <span class="keyword">if</span> (state == REFRESHING) - { - <span class="comment">// 正在刷新的时候触摸移动</span> - isTouch = <span class="keyword">true</span>; - } - } <span class="keyword">else</span> <span class="keyword">if</span> (((Pullable) pullableView).canPullUp() && canPullUp - && state != REFRESHING) - { - <span class="comment">// 可以上拉，正在刷新时不能上拉</span> - <span class="keyword">if</span> (pullUpY > <span class="number"></span>) - { - pullUpY = <span class="number"></span>; - canPullDown = <span class="keyword">true</span>; - canPullUp = <span class="keyword">false</span>; - } - <span class="keyword">if</span> (pullUpY < -getMeasuredHeight()) - pullUpY = -getMeasuredHeight(); - <span class="keyword">if</span> (state == LOADING) - { - <span class="comment">// 正在加载的时候触摸移动</span> - isTouch = <span class="keyword">true</span>; - } - } <span class="keyword">else</span> - releasePull(); - } <span class="keyword">else</span> - mEvents = <span class="number"></span>; - lastY = ev.getY(); - <span class="comment">// 根据下拉距离改变比例</span> - radio = (<span class="keyword">float</span>) (<span class="number">2</span> + <span class="number">2</span> * Math.tan(Math.PI / <span class="number">2</span> / getMeasuredHeight() - * (pullDownY + Math.abs(pullUpY)))); - requestLayout(); - <span class="keyword">if</span> (pullDownY <= refreshDist - <span style=<span class="string">&#8220;white-space:pre&#8221;</span>> </span>&& (state == RELEASE_TO_REFRESH || state == DONE)) { - <span style=<span class="string">&#8220;white-space:pre&#8221;</span>> </span><span class="comment">// 如果下拉距离没达到刷新的距离且当前状态是释放刷新，改变状态为下拉刷新</span> - <span style=<span class="string">&#8220;white-space:pre&#8221;</span>> </span>changeState(INIT); - <span style=<span class="string">&#8220;white-space:pre&#8221;</span>> </span>} - <span style=<span class="string">&#8220;white-space:pre&#8221;</span>> </span><span class="keyword">if</span> (pullDownY >= refreshDist && (state == INIT || state == DONE)) { - <span style=<span class="string">&#8220;white-space:pre&#8221;</span>> </span><span class="comment">// 如果下拉距离达到刷新的距离且当前状态是初始状态刷新，改变状态为释放刷新</span> - <span style=<span class="string">&#8220;white-space:pre&#8221;</span>> </span>changeState(RELEASE_TO_REFRESH); - <span style=<span class="string">&#8220;white-space:pre&#8221;</span>> </span>} - <span style=<span class="string">&#8220;white-space:pre&#8221;</span>> </span><span class="comment">// 下面是判断上拉加载的，同上，注意pullUpY是负值</span> - <span style=<span class="string">&#8220;white-space:pre&#8221;</span>> </span><span class="keyword">if</span> (-pullUpY <= loadmoreDist - <span style=<span class="string">&#8220;white-space:pre&#8221;</span>> </span>&& (state == RELEASE_TO_LOAD || state == DONE)) { - <span style=<span class="string">&#8220;white-space:pre&#8221;</span>> </span>changeState(INIT); - <span style=<span class="string">&#8220;white-space:pre&#8221;</span>> </span>} - <span style=<span class="string">&#8220;white-space:pre&#8221;</span>> </span><span class="keyword">if</span> (-pullUpY >= loadmoreDist && (state == INIT || state == DONE)) { - <span style=<span class="string">&#8220;white-space:pre&#8221;</span>> </span>changeState(RELEASE_TO_LOAD); - <span style=<span class="string">&#8220;white-space:pre&#8221;</span>> </span>} - <span class="comment">// 因为刷新和加载操作不能同时进行，所以pullDownY和pullUpY不会同时不为0，因此这里用(pullDownY +</span> - <span class="comment">// Math.abs(pullUpY))就可以不对当前状态作区分了</span> - <span class="keyword">if</span> ((pullDownY + Math.abs(pullUpY)) > <span class="number">8</span>) - { - <span class="comment">// 防止下拉过程中误触发长按事件和点击事件</span> - ev.setAction(MotionEvent.ACTION_CANCEL); - } - <span class="keyword">break</span>; - <span class="keyword">case</span> MotionEvent.ACTION_UP: - <span class="keyword">if</span> (pullDownY > refreshDist || -pullUpY > loadmoreDist) - <span class="comment">// 正在刷新时往下拉（正在加载时往上拉），释放后下拉头（上拉头）不隐藏</span> - isTouch = <span class="keyword">false</span>; - <span class="keyword">if</span> (state == RELEASE_TO_REFRESH) - { - changeState(REFRESHING); - <span class="comment">// 刷新操作</span> - <span class="keyword">if</span> (mListener != <span class="keyword">null</span>) - mListener.onRefresh(<span class="keyword">this</span>); - } <span class="keyword">else</span> <span class="keyword">if</span> (state == RELEASE_TO_LOAD) - { - changeState(LOADING); - <span class="comment">// 加载操作</span> - <span class="keyword">if</span> (mListener != <span class="keyword">null</span>) - mListener.onLoadMore(<span class="keyword">this</span>); - } - hide(); - <span class="keyword">default</span>: - <span class="keyword">break</span>; - } - <span class="comment">// 事件分发交给父类</span> - <span class="keyword">super</span>.dispatchTouchEvent(ev); - <span class="keyword">return</span> <span class="keyword">true</span>; - } - - <span class="keyword">private</span> <span class="keyword">void</span> initView() - { - <span class="comment">// 初始化下拉布局</span> - pullView = refreshView.findViewById(R.id.pull_icon); - refreshStateTextView = (TextView) refreshView - .findViewById(R.id.state_tv); - refreshingView = refreshView.findViewById(R.id.refreshing_icon); - refreshStateImageView = refreshView.findViewById(R.id.state_iv); - <span class="comment">// 初始化上拉布局</span> - pullUpView = loadmoreView.findViewById(R.id.pullup_icon); - loadStateTextView = (TextView) loadmoreView - .findViewById(R.id.loadstate_tv); - loadingView = loadmoreView.findViewById(R.id.loading_icon); - loadStateImageView = loadmoreView.findViewById(R.id.loadstate_iv); - } - - <span class="annotation">@Override</span> - <span class="keyword">protected</span> <span class="keyword">void</span> onLayout(<span class="keyword">boolean</span> changed, <span class="keyword">int</span> l, <span class="keyword">int</span> t, <span class="keyword">int</span> r, <span class="keyword">int</span> b) - { - <span class="keyword">if</span> (!isLayout) - { - <span class="comment">// 这里是第一次进来的时候做一些初始化</span> - refreshView = getChildAt(<span class="number"></span>); - pullableView = getChildAt(<span class="number">1</span>); - loadmoreView = getChildAt(<span class="number">2</span>); - isLayout = <span class="keyword">true</span>; - initView(); - refreshDist = ((ViewGroup) refreshView).getChildAt(<span class="number"></span>) - .getMeasuredHeight(); - loadmoreDist = ((ViewGroup) loadmoreView).getChildAt(<span class="number"></span>) - .getMeasuredHeight(); - } - <span class="comment">// 改变子控件的布局，这里直接用(pullDownY + pullUpY)作为偏移量，这样就可以不对当前状态作区分</span> - refreshView.layout(<span class="number"></span>, - refreshView.getMeasuredWidth(), (<span class="keyword">int</span>) (pullDownY + pullUpY)); - pullableView.layout(<span class="number"></span>, (<span class="keyword">int</span>) (pullDownY + pullUpY), - pullableView.getMeasuredWidth(), (<span class="keyword">int</span>) (pullDownY + pullUpY) - + pullableView.getMeasuredHeight()); - loadmoreView.layout(<span class="number"></span>, - (<span class="keyword">int</span>) (pullDownY + pullUpY) + pullableView.getMeasuredHeight(), - loadmoreView.getMeasuredWidth(), - (<span class="keyword">int</span>) (pullDownY + pullUpY) + pullableView.getMeasuredHeight() - + loadmoreView.getMeasuredHeight()); - } - - <span class="keyword">class</span> MyTimer - { - <span class="keyword">private</span> Handler handler; - <span class="keyword">private</span> Timer timer; - <span class="keyword">private</span> MyTask mTask; - - <span class="keyword">public</span> MyTimer(Handler handler) - { - <span class="keyword">this</span>.handler = handler; - timer = <span class="keyword">new</span> Timer(); - } - - <span class="keyword">public</span> <span class="keyword">void</span> schedule(<span class="keyword">long</span> period) - { - <span class="keyword">if</span> (mTask != <span class="keyword">null</span>) - { - mTask.cancel(); - mTask = <span class="keyword">null</span>; - } - mTask = <span class="keyword">new</span> MyTask(handler); - timer.schedule(mTask, <span class="number"></span>, period); - } - - <span class="keyword">public</span> <span class="keyword">void</span> cancel() - { - <span class="keyword">if</span> (mTask != <span class="keyword">null</span>) - { - mTask.cancel(); - mTask = <span class="keyword">null</span>; - } - } - - <span class="keyword">class</span> MyTask <span class="keyword">extends</span> TimerTask - { - <span class="keyword">private</span> Handler handler; - - <span class="keyword">public</span> MyTask(Handler handler) - { - <span class="keyword">this</span>.handler = handler; - } - - <span class="annotation">@Override</span> - <span class="keyword">public</span> <span class="keyword">void</span> run() - { - handler.obtainMessage().sendToTarget(); - } - - } - } - - <span class="comment">/**</span> - <span class="comment"> * 刷新加载回调接口</span> - <span class="comment"> * </span> - <span class="comment"> * @author chenjing</span> - <span class="comment"> * </span> - <span class="comment"> */</span> - <span class="keyword">public</span> <span class="keyword">interface</span> OnRefreshListener - { - <span class="comment">/**</span> - <span class="comment"> * 刷新操作</span> - <span class="comment"> */</span> - <span class="keyword">void</span> onRefresh(PullToRefreshLayout pullToRefreshLayout); - - <span class="comment">/**</span> - <span class="comment"> * 加载操作</span> - <span class="comment"> */</span> - <span class="keyword">void</span> onLoadMore(PullToRefreshLayout pullToRefreshLayout); - } - - } </div> 上面就是整个布局的代码，并不是很难。下面看各个View对Pullable接口的实现，ListView和GridView还有ExpandableListView的判断方法是一样的： PullableListView： <div class="dp-highlighter bg_java"> <div class="bar"> <div class="tools"> **[java]** [view plain](http://blog.csdn.net/zhongkejingwang/article/details/38868463#)<span class="tracking-ad" data-mod="popu_168"><span class="tracking-ad" data-mod="popu_168"> [copy](http://blog.csdn.net/zhongkejingwang/article/details/38868463#)</span></span> <div> <embed id="ZeroClipboardMovie_3" src="http://static.blog.csdn.net/scripts/ZeroClipboard/ZeroClipboard.swf" type="application/x-shockwave-flash" width="18" height="18" align="middle" name="ZeroClipboardMovie_3"> </embed> </div> </div> </div> - <span class="keyword">package</span> com.jingchen.pulltorefresh.pullableview; - - <span class="keyword">import</span> android.content.Context; - <span class="keyword">import</span> android.util.AttributeSet; - <span class="keyword">import</span> android.util.Log; - <span class="keyword">import</span> android.widget.ListView; - - <span class="keyword">public</span> <span class="keyword">class</span> PullableListView <span class="keyword">extends</span> ListView <span class="keyword">implements</span> Pullable - { - - <span class="keyword">public</span> PullableListView(Context context) - { - <span class="keyword">super</span>(context); - } - - <span class="keyword">public</span> PullableListView(Context context, AttributeSet attrs) - { - <span class="keyword">super</span>(context, attrs); - } - - <span class="keyword">public</span> PullableListView(Context context, AttributeSet attrs, <span class="keyword">int</span> defStyle) - { - <span class="keyword">super</span>(context, attrs, defStyle); - } - - <span class="annotation">@Override</span> - <span class="keyword">public</span> <span class="keyword">boolean</span> canPullDown() - { - <span class="keyword">if</span> (getCount() == <span class="number"></span>) - { - <span class="comment">// 没有item的时候也可以下拉刷新</span> - <span class="keyword">return</span> <span class="keyword">true</span>; - } <span class="keyword">else</span> <span class="keyword">if</span> (getFirstVisiblePosition() == <span class="number"></span> - && getChildAt(<span class="number"></span>).getTop() >= <span class="number"></span>) - { - <span class="comment">// 滑到ListView的顶部了</span> - <span class="keyword">return</span> <span class="keyword">true</span>; - } <span class="keyword">else</span> - <span class="keyword">return</span> <span class="keyword">false</span>; - } - - <span class="annotation">@Override</span> - <span class="keyword">public</span> <span class="keyword">boolean</span> canPullUp() - { - <span class="keyword">if</span> (getCount() == <span class="number"></span>) - { - <span class="comment">// 没有item的时候也可以上拉加载</span> - <span class="keyword">return</span> <span class="keyword">true</span>; - { - <span class="comment">// 滑到底部了</span> - && getChildAt( - getLastVisiblePosition() - <span class="keyword">return</span> <span class="keyword">true</span>; - } - <span class="keyword">return</span> <span class="keyword">false</span>; - } - } </div> PullableExpandableListView： <div class="dp-highlighter bg_java"> <div class="bar"> <div class="tools"> **[java]** [view plain](http://blog.csdn.net/zhongkejingwang/article/details/38868463#)<span class="tracking-ad" data-mod="popu_168"><span class="tracking-ad" data-mod="popu_168"> [copy](http://blog.csdn.net/zhongkejingwang/article/details/38868463#)</span></span> <div> <embed id="ZeroClipboardMovie_4" src="http://static.blog.csdn.net/scripts/ZeroClipboard/ZeroClipboard.swf" type="application/x-shockwave-flash" width="18" height="18" align="middle" name="ZeroClipboardMovie_4"> </embed> </div> </div> </div> - <span class="keyword">package</span> com.jingchen.pulltorefresh.pullableview; - - <span class="keyword">import</span> android.content.Context; - <span class="keyword">import</span> android.util.AttributeSet; - <span class="keyword">import</span> android.widget.ExpandableListView; - - <span class="keyword">public</span> <span class="keyword">class</span> PullableExpandableListView <span class="keyword">extends</span> ExpandableListView <span class="keyword">implements</span> - Pullable - { - - <span class="keyword">public</span> PullableExpandableListView(Context context) - { - <span class="keyword">super</span>(context); - } - - <span class="keyword">public</span> PullableExpandableListView(Context context, AttributeSet attrs) - { - <span class="keyword">super</span>(context, attrs); - } - - <span class="keyword">public</span> PullableExpandableListView(Context context, AttributeSet attrs, - <span class="keyword">int</span> defStyle) - { - <span class="keyword">super</span>(context, attrs, defStyle); - } - - <span class="annotation">@Override</span> - <span class="keyword">public</span> <span class="keyword">boolean</span> canPullDown() - { - <span class="keyword">if</span> (getCount() == <span class="number"></span>) - { - <span class="comment">// 没有item的时候也可以下拉刷新</span> - <span class="keyword">return</span> <span class="keyword">true</span>; - } <span class="keyword">else</span> <span class="keyword">if</span> (getFirstVisiblePosition() == <span class="number"></span> - && getChildAt(<span class="number"></span>).getTop() >= <span class="number"></span>) - { - <span class="comment">// 滑到顶部了</span> - <span class="keyword">return</span> <span class="keyword">true</span>; - } <span class="keyword">else</span> - <span class="keyword">return</span> <span class="keyword">false</span>; - } - - <span class="annotation">@Override</span> - <span class="keyword">public</span> <span class="keyword">boolean</span> canPullUp() - { - <span class="keyword">if</span> (getCount() == <span class="number"></span>) - { - <span class="comment">// 没有item的时候也可以上拉加载</span> - <span class="keyword">return</span> <span class="keyword">true</span>; - { - <span class="comment">// 滑到底部了</span> - && getChildAt( - getLastVisiblePosition() - <span class="keyword">return</span> <span class="keyword">true</span>; - } - <span class="keyword">return</span> <span class="keyword">false</span>; - } - - } </div> PullableGridView： <div class="dp-highlighter bg_java"> <div class="bar"> <div class="tools"> **[java]** [view plain](http://blog.csdn.net/zhongkejingwang/article/details/38868463#)<span class="tracking-ad" data-mod="popu_168"><span class="tracking-ad" data-mod="popu_168"> [copy](http://blog.csdn.net/zhongkejingwang/article/details/38868463#)</span></span> <div> <embed id="ZeroClipboardMovie_5" src="http://static.blog.csdn.net/scripts/ZeroClipboard/ZeroClipboard.swf" type="application/x-shockwave-flash" width="18" height="18" align="middle" name="ZeroClipboardMovie_5"> </embed> </div> </div> </div> - <span class="keyword">package</span> com.jingchen.pulltorefresh.pullableview; - - <span class="keyword">import</span> android.content.Context; - <span class="keyword">import</span> android.util.AttributeSet; - <span class="keyword">import</span> android.widget.GridView; - - <span class="keyword">public</span> <span class="keyword">class</span> PullableGridView <span class="keyword">extends</span> GridView <span class="keyword">implements</span> Pullable - { - - <span class="keyword">public</span> PullableGridView(Context context) - { - <span class="keyword">super</span>(context); - } - - <span class="keyword">public</span> PullableGridView(Context context, AttributeSet attrs) - { - <span class="keyword">super</span>(context, attrs); - } - - <span class="keyword">public</span> PullableGridView(Context context, AttributeSet attrs, <span class="keyword">int</span> defStyle) - { - <span class="keyword">super</span>(context, attrs, defStyle); - } - - <span class="annotation">@Override</span> - <span class="keyword">public</span> <span class="keyword">boolean</span> canPullDown() - { - <span class="keyword">if</span> (getCount() == <span class="number"></span>) - { - <span class="comment">// 没有item的时候也可以下拉刷新</span> - <span class="keyword">return</span> <span class="keyword">true</span>; - } <span class="keyword">else</span> <span class="keyword">if</span> (getFirstVisiblePosition() == <span class="number"></span> - && getChildAt(<span class="number"></span>).getTop() >= <span class="number"></span>) - { - <span class="comment">// 滑到顶部了</span> - <span class="keyword">return</span> <span class="keyword">true</span>; - } <span class="keyword">else</span> - <span class="keyword">return</span> <span class="keyword">false</span>; - } - - <span class="annotation">@Override</span> - <span class="keyword">public</span> <span class="keyword">boolean</span> canPullUp() - { - <span class="keyword">if</span> (getCount() == <span class="number"></span>) - { - <span class="comment">// 没有item的时候也可以上拉加载</span> - <span class="keyword">return</span> <span class="keyword">true</span>; - { - <span class="comment">// 滑到底部了</span> - && getChildAt( - getLastVisiblePosition() - <span class="keyword">return</span> <span class="keyword">true</span>; - } - <span class="keyword">return</span> <span class="keyword">false</span>; - } - - } </div> PullableScrollView： <div class="dp-highlighter bg_java"> <div class="bar"> <div class="tools"> **[java]** [view plain](http://blog.csdn.net/zhongkejingwang/article/details/38868463#)<span class="tracking-ad" data-mod="popu_168"><span class="tracking-ad" data-mod="popu_168"> [copy](http://blog.csdn.net/zhongkejingwang/article/details/38868463#)</span></span> <div> <embed id="ZeroClipboardMovie_6" src="http://static.blog.csdn.net/scripts/ZeroClipboard/ZeroClipboard.swf" type="application/x-shockwave-flash" width="18" height="18" align="middle" name="ZeroClipboardMovie_6"> </embed> </div> </div> </div> - <span class="keyword">package</span> com.jingchen.pulltorefresh.pullableview; - - <span class="keyword">import</span> android.content.Context; - <span class="keyword">import</span> android.util.AttributeSet; - <span class="keyword">import</span> android.widget.ScrollView; - - <span class="keyword">public</span> <span class="keyword">class</span> PullableScrollView <span class="keyword">extends</span> ScrollView <span class="keyword">implements</span> Pullable - { - - <span class="keyword">public</span> PullableScrollView(Context context) - { - <span class="keyword">super</span>(context); - } - - <span class="keyword">public</span> PullableScrollView(Context context, AttributeSet attrs) - { - <span class="keyword">super</span>(context, attrs); - } - - <span class="keyword">public</span> PullableScrollView(Context context, AttributeSet attrs, <span class="keyword">int</span> defStyle) - { - <span class="keyword">super</span>(context, attrs, defStyle); - } - - <span class="annotation">@Override</span> - <span class="keyword">public</span> <span class="keyword">boolean</span> canPullDown() - { - <span class="keyword">if</span> (getScrollY() == <span class="number"></span>) - <span class="keyword">return</span> <span class="keyword">true</span>; - <span class="keyword">else</span> - <span class="keyword">return</span> <span class="keyword">false</span>; - } - - <span class="annotation">@Override</span> - <span class="keyword">public</span> <span class="keyword">boolean</span> canPullUp() - { - <span class="keyword">return</span> <span class="keyword">true</span>; - <span class="keyword">else</span> - <span class="keyword">return</span> <span class="keyword">false</span>; - } - - } </div> PullableWebView： <div class="dp-highlighter bg_java"> <div class="bar"> <div class="tools"> **[java]** [view plain](http://blog.csdn.net/zhongkejingwang/article/details/38868463#)<span class="tracking-ad" data-mod="popu_168"><span class="tracking-ad" data-mod="popu_168"> [copy](http://blog.csdn.net/zhongkejingwang/article/details/38868463#)</span></span> <div> <embed id="ZeroClipboardMovie_7" src="http://static.blog.csdn.net/scripts/ZeroClipboard/ZeroClipboard.swf" type="application/x-shockwave-flash" width="18" height="18" align="middle" name="ZeroClipboardMovie_7"> </embed> </div> </div> </div> - <span class="keyword">package</span> com.jingchen.pulltorefresh.pullableview; - - <span class="keyword">import</span> android.content.Context; - <span class="keyword">import</span> android.util.AttributeSet; - <span class="keyword">import</span> android.webkit.WebView; - - <span class="keyword">public</span> <span class="keyword">class</span> PullableWebView <span class="keyword">extends</span> WebView <span class="keyword">implements</span> Pullable - { - - <span class="keyword">public</span> PullableWebView(Context context) - { - <span class="keyword">super</span>(context); - } - - <span class="keyword">public</span> PullableWebView(Context context, AttributeSet attrs) - { - <span class="keyword">super</span>(context, attrs); - } - - <span class="keyword">public</span> PullableWebView(Context context, AttributeSet attrs, <span class="keyword">int</span> defStyle) - { - <span class="keyword">super</span>(context, attrs, defStyle); - } - - <span class="annotation">@Override</span> - <span class="keyword">public</span> <span class="keyword">boolean</span> canPullDown() - { - <span class="keyword">if</span> (getScrollY() == <span class="number"></span>) - <span class="keyword">return</span> <span class="keyword">true</span>; - <span class="keyword">else</span> - <span class="keyword">return</span> <span class="keyword">false</span>; - } - - <span class="annotation">@Override</span> - <span class="keyword">public</span> <span class="keyword">boolean</span> canPullUp() - { - <span class="keyword">if</span> (getScrollY() >= getContentHeight() * getScale() - <span class="keyword">return</span> <span class="keyword">true</span>; - <span class="keyword">else</span> - <span class="keyword">return</span> <span class="keyword">false</span>; - } - } </div> ImageView和TextView就不贴了，我直接在方法里返回了true。OK了，整个demo的代码有点多，就不贴了。 [源码下载](http://download.csdn.net/detail/zhongkejingwang/7828061)

win R -> 输入 cmd 回车 ，打开命令行界面 在标题栏上右键，属性 勾选使用旧版控制台  转自：http://www.jianshu.com/p/0ed41f13fd6a

Android 高清加载巨图方案 拒绝压缩图片 转载请标明出处：http://blog.csdn.net/lmj623565791/article/details/49300989； 一、概述 距离上一篇博客有段时间没更新了，主要是最近有些私事导致的，那么就先来一篇简单一点的博客脉动回来。 对于加载图片，大家都不陌生，一般为了尽可能避免OOM都会按照如下做法： 对于图片显示：根据需要显示图片控件的大小对图片进行压缩显示。 如果图片数量非常多：则会使用LruCache等缓存机制，将所有图片占据的内容维持在一个范围内。 其实对于图片加载还有种情况，就是单个图片非常巨大，并且还不允许压缩。比如显示：世界地图、清明上河图、微博长图等。 那么对于这种需求，该如何做呢？ 首先不压缩，按照原图尺寸加载，那么屏幕肯定是不够大的，并且考虑到内存的情况，不可能一次性整图加载到内存中，所以肯定是局部加载，那么就需要用到一个类： BitmapRegionDecoder 其次，既然屏幕显示不完，那么最起码要添加一个上下左右拖动的手势，让用户可以拖动查看。 那么综上，本篇博文的目的就是去自定义一个显示巨图的View，支持用户去拖动查看，大概的效果图如下： 好吧，这清明上河图太长了，想要观看全图，文末下载，图片在assets目录。当然如果你的图，高度也很大，肯定也是可以上下拖动的。 二、初识BitmapRegionDecoder BitmapRegionDecoder主要用于显示图片的某一块矩形区域，如果你需要显示某个图片的指定区域，那么这个类非常合适。 对于该类的用法，非常简单，既然是显示图片的某一块区域，那么至少只需要一个方法去设置图片；一个方法传入显示的区域即可；详见： BitmapRegionDecoder提供了一系列的newInstance方法来构造对象，支持传入文件路径，文件描述符，文件的inputstrem等。例如： ``` BitmapRegionDecoder bitmapRegionDecoder = BitmapRegionDecoder.newInstance(inputStream, &lt;span class="hljs-keyword">false&lt;/span>); * 上述解决了传入我们需要处理的图片，那么接下来就是显示指定的区域。 ``` `bitmapRegionDecoder.decodeRegion(rect, options);` 参数一很明显是一个rect，参数二是BitmapFactory.Options，你可以控制图片的`inSampleSize`,`inPreferredConfig`等。 那么下面看一个超级简单的例子： ``` `<span class=“hljs-keyword”>package</span> com.zhy.blogcodes.largeImage; <span class=“hljs-keyword”>import</span> android.graphics.Bitmap; <span class=“hljs-keyword”>import</span> android.graphics.BitmapFactory; <span class=“hljs-keyword”>import</span> android.graphics.BitmapRegionDecoder; <span class=“hljs-keyword”>import</span> android.graphics.Rect; <span class=“hljs-keyword”>import</span> android.os.Bundle; <span class=“hljs-keyword”>import</span> android.support.v7.app.AppCompatActivity; <span class=“hljs-keyword”>import</span> android.widget.ImageView; <span class=“hljs-keyword”>import</span> com.zhy.blogcodes.R; <span class=“hljs-keyword”>import</span> java.io.IOException; <span class=“hljs-keyword”>import</span> java.io.InputStream; ...

对于图片加载有一种这样的情况，就是单个图片非常巨大，并且还不允许压缩。比如显示：世界地图、微博长图等。首先不压缩，按照原图尺寸加载，那么屏幕肯定是不够大的，并且考虑到内存的情况，不可能一次性整图加载到内存中，所以肯定是局部加载。这就需要用到Api提供的这个类：BitmapRegionDecoder。 ### <a name="t1"></a>BitmapRegionDecoder 我们来看一下官方的介绍： ``` `BitmapRegionDecoder can be used <span class=“hljs-built_in”>to</span> decode <span class=“hljs-operator”>a</span> rectangle region <span class=“hljs-built_in”>from</span> <span class=“hljs-operator”>an</span> image. BitmapRegionDecoder is particularly useful when <span class=“hljs-operator”>an</span> original image is large <span class=“hljs-operator”>and</span> you only need parts <span class=“hljs-operator”>of</span> <span class=“hljs-operator”>the</span> image. To <span class=“hljs-built_in”>create</span> <span class=“hljs-operator”>a</span> BitmapRegionDecoder, call newInstance(…). Given <span class=“hljs-operator”>a</span> BitmapRegionDecoder, users can call decodeRegion() repeatedly <span class=“hljs-built_in”>to</span> <span class=“hljs-built_in”>get</span> <span class=“hljs-operator”>a</span> decoded Bitmap <span class=“hljs-operator”>of</span> <span class=“hljs-operator”>the</span> specified region.` ...