【Android代码片段之八】监听Android屏幕是否锁屏

来源：互联网发布：三合一cms 编辑：程序博客网时间：2024/06/06 03:23

原文网址：http://blog.csdn.net/m_changgong/article/details/7608911作者：张燕广

实现方法：1）通过BroadcastReceiver接收广播Intent.ACTION_SCREEN_ON和Intent.ACTION_SCREEN_OFF可以判断屏幕状态是否锁屏，但是只有屏幕状态发生改变时才会发出广播；

2）如果要在屏幕状态发生改变之前就想获取屏幕状态，可以通过反射机制调用PowerManager的isScreenOn方法。

具体实现，见代码：

实现Screen状态监听的类ScreenObserver，实现如下：

<pre name="code" class="java">public class ScreenObserver {private static String TAG = "ScreenObserver";      private Context mContext;      private ScreenBroadcastReceiver mScreenReceiver;      private ScreenStateListener mScreenStateListener;      private static Method mReflectScreenState;            public ScreenObserver(Context context){          mContext = context;          mScreenReceiver = new ScreenBroadcastReceiver();          try {              mReflectScreenState = PowerManager.class.getMethod("isScreenOn",                      new Class[] {});          } catch (NoSuchMethodException nsme) {              Log.d(TAG, "API < 7," + nsme);          }      }            /**      * screen状态广播接收者      * @author zhangyg      *      */      private class ScreenBroadcastReceiver extends BroadcastReceiver{          private String action = null;          @Override          public void onReceive(Context context, Intent intent) {              action = intent.getAction();              if(Intent.ACTION_SCREEN_ON.equals(action)){                  mScreenStateListener.onScreenOn();              }else if(Intent.ACTION_SCREEN_OFF.equals(action)){                  mScreenStateListener.onScreenOff();              }          }      }                  /**      * 请求screen状态更新      * @param listener      */      public void requestScreenStateUpdate(ScreenStateListener listener) {          mScreenStateListener = listener;          startScreenBroadcastReceiver();                    firstGetScreenState();      }            /**      * 第一次请求screen状态      */      private void firstGetScreenState(){          PowerManager manager = (PowerManager) mContext                  .getSystemService(Activity.POWER_SERVICE);          if (isScreenOn(manager)) {              if (mScreenStateListener != null) {                  mScreenStateListener.onScreenOn();              }          } else {              if (mScreenStateListener != null) {                  mScreenStateListener.onScreenOff();              }          }      }            /**      * 停止screen状态更新      */      public void stopScreenStateUpdate(){          mContext.unregisterReceiver(mScreenReceiver);      }            /**      * 启动screen状态广播接收器      */      private void startScreenBroadcastReceiver(){          IntentFilter filter = new IntentFilter();          filter.addAction(Intent.ACTION_SCREEN_ON);          filter.addAction(Intent.ACTION_SCREEN_OFF);          mContext.registerReceiver(mScreenReceiver, filter);      }            /**      * screen是否打开状态      * @param pm      * @return      */      private static boolean isScreenOn(PowerManager pm) {          boolean screenState;          try {              screenState = (Boolean) mReflectScreenState.invoke(pm);          } catch (Exception e) {              screenState = false;          }          return screenState;      }            public interface ScreenStateListener {          public void onScreenOn();          public void onScreenOff();      }  }

测试ScreenObserver功能的示例类ScreenObserverActivity，实现如下：

public class ScreenObserverActivity extends Activity { private String TAG = "ScreenObserverActivity";      private ScreenObserver mScreenObserver;            @Override      public void onCreate(Bundle savedInstanceState) {          super.onCreate(savedInstanceState);          setContentView(R.layout.main);            mScreenObserver = new ScreenObserver(this);          mScreenObserver.requestScreenStateUpdate(new ScreenStateListener() {              @Override              public void onScreenOn() {                  doSomethingOnScreenOn();              }                @Override              public void onScreenOff() {                  doSomethingOnScreenOff();              }          });      }        private void doSomethingOnScreenOn() {          Log.i(TAG, "Screen is on");      }        private void doSomethingOnScreenOff() {          Log.i(TAG, "Screen is off");      }            @Override      protected void onDestroy() {          super.onDestroy();          //停止监听screen状态          mScreenObserver.stopScreenStateUpdate();      }  }

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