StrictMode的使用（转）

  ANR窗口产生的原因是多种多样的。程序的主线程因为IO读写或网络阻塞而导致被阻塞了，外部存储设备被独占了或系统负荷（load）过高（即不是自己编写的程序的问题，可能是系统或者其他第三方程序导致的问题），都有可能导致ANR窗口的出现。

  从Android 2.3开始提供了一个新的类StrictMode，可以帮助开发者改进他们的Android应用，StrictMode可以用于捕捉发生在应用程序主线程中耗时的磁盘、网络访问或函数调用，可以帮助开发者使其改进程序，使主线程处理UI和动画在磁盘读写和网络操作时变得更平滑，避免主线程被阻塞，导致ANR窗口的发生。

 下面简要说明下Android 2.3新特性StrictMode限制模式的工作方式，见下面的代码：

publicvoid onCreate() {
if (DEVELOPER_MODE) {
StrictMode.setThreadPolicy(new StrictMode.ThreadPolicy.Builder()
.detectDiskReads()
.detectDiskWrites()
.detectNetwork() // 这里可以替换为detectAll() 就包括了磁盘读写和网络I/O
.penaltyLog() //打印logcat，当然也可以定位到dropbox，通过文件保存相应的log
.build());
StrictMode.setVmPolicy(new StrictMode.VmPolicy.Builder()
.detectLeakedSqlLiteObjects() //探测SQLite数据库操作
.penaltyLog() //打印logcat
.penaltyDeath()
.build());
}
super.onCreate();
}

上述代码可以在Application的OnCreate中添加，这样就能在程序启动的最初一刻进行监控了。

输出log如下：

02-27 10:03:56.122: DEBUG/StrictMode(16210): StrictMode policy violation; ~duration=696 ms: android.os.StrictMode$StrictModeDiskReadViolation: policy=23 violation=2
02-27 10:03:56.122: DEBUG/StrictMode(16210): at android.os.StrictMode$AndroidBlockGuardPolicy.onReadFromDisk(StrictMode.java:745)
02-27 10:03:56.122: DEBUG/StrictMode(16210): at dalvik.system.BlockGuard$WrappedFileSystem.open(BlockGuard.java:228)
02-27 10:03:56.122: DEBUG/StrictMode(16210): at java.io.FileOutputStream.<init>(FileOutputStream.java:94)
02-27 10:03:56.122: DEBUG/StrictMode(16210): at java.io.FileOutputStream.<init>(FileOutputStream.java:66)
02-27 10:03:56.122: DEBUG/StrictMode(16210): at java.io.FileWriter.<init>(FileWriter.java:42)
02-27 10:03:56.122: DEBUG/StrictMode(16210): at org.zelos.asm.main.writeFile(main.java:30)
02-27 10:03:56.122: DEBUG/StrictMode(16210): at org.zelos.asm.main.onCreate(main.java:19)
02-27 10:03:56.122: DEBUG/StrictMode(16210): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
02-27 10:03:56.122: DEBUG/StrictMode(16210): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
02-27 10:03:56.122: DEBUG/StrictMode(16210): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
02-27 10:03:56.122: DEBUG/StrictMode(16210): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
02-27 10:03:56.122: DEBUG/StrictMode(16210): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
02-27 10:03:56.122: DEBUG/StrictMode(16210): at android.os.Handler.dispatchMessage(Handler.java:99)
02-27 10:03:56.122: DEBUG/StrictMode(16210): at android.os.Looper.loop(Looper.java:123)
02-27 10:03:56.122: DEBUG/StrictMode(16210): at android.app.ActivityThread.main(ActivityThread.java:3683)
02-27 10:03:56.122: DEBUG/StrictMode(16210): at java.lang.reflect.Method.invokeNative(Native Method)
02-27 10:03:56.122: DEBUG/StrictMode(16210): at java.lang.reflect.Method.invoke(Method.java:507)
02-27 10:03:56.122: DEBUG/StrictMode(16210): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
02-27 10:03:56.122: DEBUG/StrictMode(16210): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
02-27 10:03:56.122: DEBUG/StrictMode(16210): at dalvik.system.NativeStart.main(Native Method)
02-27 10:03:56.162: DEBUG/StrictMode(16210): StrictMode policy violation; ~duration=619 ms: android.os.StrictMode$StrictModeDiskWriteViolation: policy=23 violation=1
02-27 10:03:56.162: DEBUG/StrictMode(16210): at android.os.StrictMode$AndroidBlockGuardPolicy.onWriteToDisk(StrictMode.java:732)
02-27 10:03:56.162: DEBUG/StrictMode(16210): at dalvik.system.BlockGuard$WrappedFileSystem.open(BlockGuard.java:230)
02-27 10:03:56.162: DEBUG/StrictMode(16210): at java.io.FileOutputStream.<init>(FileOutputStream.java:94)
02-27 10:03:56.162: DEBUG/StrictMode(16210): at java.io.FileOutputStream.<init>(FileOutputStream.java:66)
02-27 10:03:56.162: DEBUG/StrictMode(16210): at java.io.FileWriter.<init>(FileWriter.java:42)
02-27 10:03:56.162: DEBUG/StrictMode(16210): at org.zelos.asm.main.writeFile(main.java:30)
02-27 10:03:56.162: DEBUG/StrictMode(16210): at org.zelos.asm.main.onCreate(main.java:19)
02-27 10:03:56.162: DEBUG/StrictMode(16210): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
02-27 10:03:56.162: DEBUG/StrictMode(16210): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
02-27 10:03:56.162: DEBUG/StrictMode(16210): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
02-27 10:03:56.162: DEBUG/StrictMode(16210): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
02-27 10:03:56.162: DEBUG/StrictMode(16210): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
02-27 10:03:56.162: DEBUG/StrictMode(16210): at android.os.Handler.dispatchMessage(Handler.java:99)
02-27 10:03:56.162: DEBUG/StrictMode(16210): at android.os.Looper.loop(Looper.java:123)
02-27 10:03:56.162: DEBUG/StrictMode(16210): at android.app.ActivityThread.main(ActivityThread.java:3683)
02-27 10:03:56.162: DEBUG/StrictMode(16210): at java.lang.reflect.Method.invokeNative(Native Method)
02-27 10:03:56.162: DEBUG/StrictMode(16210): at java.lang.reflect.Method.invoke(Method.java:507)
02-27 10:03:56.162: DEBUG/StrictMode(16210): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
02-27 10:03:56.162: DEBUG/StrictMode(16210): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
02-27 10:03:56.162: DEBUG/StrictMode(16210): at dalvik.system.NativeStart.main(Native Method)

All of this is well and good, but it doesn’t work on Android  prior to version 2.3. To use 
StrictMode explicitly, you have to deploy to an  environment running Andr oid 2.3 or later. 
If you deploy to anything olde r than 2.3, you’re going to get  verify errors because this 
class just doesn’t exist  prior to Android 2.3.