(转)StrictMode使用详解，strictmode

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StrictMode使用详解，strictmode

StrictMode

    StrictMode最常用来捕捉应用程序的主线程，它将报告与线程及虚拟机相关的策略违例。一旦检测到策略违例（policy violation），你将获得警告，其包含了一个栈trace显示你的应用在何处发生违例。除了主线程，我们还可以在Handler，AsyncTask，AsyncQueryHandler，IntentService等API中使用StrictMode。

检查策略

StrictMode的线程策略主要用于检测磁盘IO和网络访问，而虚拟机策略主要用于检测内存泄漏现象。Android已经在磁盘IO访问和网络访问的代码中已经加入了StrictMode。当监视的线程发生策略的违例时，就可以获得警告，例如写入LogCat，显示一个对话框，闪下屏幕，写入DropBox日志文件，或让应用崩溃。最通常的做法是写入LogCat或让应用崩溃。下面的代码展示了如何使用StrictMode的检查策略：

public void onCreate() {
     if (DEVELOPER_MODE) {
         StrictMode.setThreadPolicy(new StrictMode.ThreadPolicy.Builder()
                 .detectDiskReads()
                 .detectDiskWrites()
                 .penaltyDialog()
                 .detectNetwork()   // or .detectAll() for all detectable problems
                 .penaltyLog()
                 .build());
         StrictMode.setVmPolicy(new StrictMode.VmPolicy.Builder()
                 .detectLeakedSqlLiteObjects()
                 .detectLeakedClosableObjects()
                 .penaltyLog()
                 .penaltyDeath()
                 .build());
     }
     super.onCreate();
 }

使用方法

如果不指定检测函数，也可以用detectAll()来替代。penaltyLog()表示将警告输出到LogCat，你也可以使用其他或增加新的惩罚（penalty）函数，例如使用penaltyDeath()的话，一旦StrictMode消息被写到LogCat后应用就会崩溃。具体支持的监视方法见：https://developer.android.com/reference/android/os/StrictMode.ThreadPolicy.Builder.html与https://developer.android.com/reference/android/os/StrictMode.VmPolicy.Builder.html
在正式版本中，我们并不希望使用StrictMode来让用户的应用因为一个警告而崩溃，所以在应用正式发布时，需要移出这些监视。你可以通过删除代码来实现，不过这里提供一个更好的方式来解决这个问题，即使用AndroidMainifest文件中的debuggable属性来实现，代码如下所示：

android:debuggable="true"

在代码中，使用方法如下所示：

// Return if this application is not in debug mode 
ApplicationInfo appInfo = context.getApplicationInfo(); 
int appFlags = appInfo.flags; 
if ((appFlags & ApplicationInfo.FLAG_DEBUGGABLE) != 0) { 
    // Do StrictMode setup here 
    StrictMode.setVmPolicy(new StrictMode.VmPolicy.Builder() 
        .detectLeakedSqlLiteObjects() 
        .penaltyLog() 
        .penaltyDeath() 
        .build()); 
}

StrictMode实例

我们在测试代码的主线程中去访问网络，这样就一定会触发StrictMode的线程监测，代码如下所示：

public class MainActivity extends Activity {

    private HttpResponse httpResponse = null;
    private HttpEntity httpEntity = null;
    private TextView mTextView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        StrictMode.setThreadPolicy(new StrictMode.ThreadPolicy.Builder()
                .detectDiskReads()
                .detectDiskWrites()
                .detectNetwork()
                .penaltyDialog()
                .penaltyLog()
                .build());
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mTextView = (TextView) findViewById(R.id.text);
        HttpGet httpGet = new HttpGet("http://www.baidu.com");
        HttpClient httpClient = new DefaultHttpClient();
        InputStream inputStream = null;
        try {
            httpResponse = httpClient.execute(httpGet);
            httpEntity = httpResponse.getEntity();
            if (httpResponse.getStatusLine().getStatusCode() == 200) {
                inputStream = httpEntity.getContent();
                BufferedReader reader = 
                      new BufferedReader(new InputStreamReader(inputStream));
                mTextView.setText(reader.readLine());
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                inputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

运行代码，并将Log信息保存到本地，在Log中，我们可以搜索D/StrictMode(15454): StrictMode policy violation关键字。这里截取一段，如下所示：

D/StrictMode(15454): StrictMode policy violation; ~duration=461 ms:
 android.os.StrictMode$StrictModeNetworkViolation: policy=55 violation=4
D/StrictMode(15454):    at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1153)
D/StrictMode(15454):    at libcore.io.BlockGuardOs.recvfrom(BlockGuardOs.java:249)
D/StrictMode(15454):    at libcore.io.IoBridge.recvfrom(IoBridge.java:553)
D/StrictMode(15454):    at java.net.PlainSocketImpl.read(PlainSocketImpl.java:485)
D/StrictMode(15454):    at java.net.PlainSocketImpl.access$000(PlainSocketImpl.java:37)
D/StrictMode(15454):    at java.net.PlainSocketImpl$PlainSocketInputStream.read(PlainSocketImpl.java:237)
D/StrictMode(15454):    at org.apache.http.impl.io.AbstractSessionInputBuffer.fillBuffer(AbstractSessionInputBuffer.java:103)
D/StrictMode(15454):    at org.apache.http.impl.io.AbstractSessionInputBuffer.read(AbstractSessionInputBuffer.java:134)
D/StrictMode(15454):    at org.apache.http.impl.io.ChunkedInputStream.read(ChunkedInputStream.java:161)
D/StrictMode(15454):    at org.apache.http.impl.io.ChunkedInputStream.read(ChunkedInputStream.java:175)
D/StrictMode(15454):    at org.apache.http.impl.io.ChunkedInputStream.exhaustInputStream(ChunkedInputStream.java:289)
D/StrictMode(15454):    at org.apache.http.impl.io.ChunkedInputStream.close(ChunkedInputStream.java:262)
D/StrictMode(15454):    at org.apache.http.conn.BasicManagedEntity.streamClosed(BasicManagedEntity.java:179)
D/StrictMode(15454):    at org.apache.http.conn.EofSensorInputStream.checkClose(EofSensorInputStream.java:266)
D/StrictMode(15454):    at org.apache.http.conn.EofSensorInputStream.close(EofSensorInputStream.java:213)
D/StrictMode(15454):    at com.imooc.strictmodetest.MainActivity.onCreate(MainActivity.java:53)
D/StrictMode(15454):    at android.app.Activity.performCreate(Activity.java:5976)
D/StrictMode(15454):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
D/StrictMode(15454):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2262)
D/StrictMode(15454):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2371)
D/StrictMode(15454):    at android.app.ActivityThread.access$800(ActivityThread.java:149)
D/StrictMode(15454):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1289)
D/StrictMode(15454):    at android.os.Handler.dispatchMessage(Handler.java:102)
D/StrictMode(15454):    at android.os.Looper.loop(Looper.java:135)
D/StrictMode(15454):    at android.app.ActivityThread.main(ActivityThread.java:5260)
D/StrictMode(15454):    at java.lang.reflect.Method.invoke(Native Method)
D/StrictMode(15454):    at java.lang.reflect.Method.invoke(Method.java:372)
D/StrictMode(15454):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:898)
D/StrictMode(15454):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:693)

Log中可以显示出StrictMode提示的原因，通过这里的TraceLog我们就可以来找到优化的方法。除了在Logcat中查看StrictMode的日志信息，如果你使用了penaltyDropbox()方法，那么你还可以通过如下所示的命令来调用DropBoxManager观察StrictMode日志：

adb shell dumpsys dropbox data_app_strictmode --print

输出日志文件如下所示：

========================================
2015-03-09 17:47:14 data_app_strictmode (text, 2177 bytes)
Process: com.imooc.strictmodetest
Flags: 0x88be46
Package: com.imooc.strictmodetest v1 (1.0)
Build: TCL/idol347/idol347:5.0.2/LRX22G/1040:userdebug/release-keys
System-App: false
Uptime-Millis: 389545133
Loop-Violation-Number: 4
Duration-Millis: 520
android.os.StrictMode$StrictModeNetworkViolation: policy=183 violation=4
    at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1153)
    at java.net.InetAddress.lookupHostByName(InetAddress.java:418)
    at java.net.InetAddress.getAllByNameImpl(InetAddress.java:252)
    at java.net.InetAddress.getAllByName(InetAddress.java:215)
    at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:137)
    at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
    at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
    at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360)
    at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
    at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
    at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
    at com.imooc.strictmodetest.MainActivity.onCreate(MainActivity.java:43)
    at android.app.Activity.performCreate(Activity.java:5976)
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2262)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2371)
    at android.app.ActivityThread.access$800(ActivityThread.java:149)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1289)
    at android.os.Handler.dispatchMessage(Handler.java:102)
    at android.os.Looper.loop(Looper.java:135)
    at android.app.ActivityThread.main(ActivityThread.java:5260)
    at java.lang.reflect.Method.invoke(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:372)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:898)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:693)

同时，如果使用了penaltyDialog()方法，在应用中还会弹出如下所示的提示框：

暂停监测
如果在程序运行中无法避免的会违反StrictMode中的一些定义好的策略，而我们又希望能够暂时忽略这些策略的监视，我们可以使用permitXXXXX方法来暂停这些内容的监测，在做完需要忽略的监测之后，再起用监测，代码如下所示：

StrictMode.ThreadPolicy old = StrictMode.getThreadPolicy();
StrictMode.setThreadPolicy(new StrictMode.ThreadPolicy.Builder(old)
        .permitDiskWrites()
        .build());
//doSomethingWriteToDisk();
StrictMode.setThreadPolicy(old);