BroadcastReceiver之实现锁屏、解锁例子

好久没有写android的小例子了，由于前几天写了一篇关于Intent.Action的文章（http://blog.csdn.net/ljphhj/article/details/38796739），有朋友私信问我关于ACTION_SCREEN_ON和ACTION_SCREEN_OFF还有ACTION_USER_PRESENT三个Action的用法，由于作为一个总结博文，当时并没有详细讲，ACTION_SCREEN_ON和ACTION_SCREEN_OFF只能通过动态注册的方式（代码内context.register和unregister），而ACTION_USER_PRESENT则是动态、静态注册两种方式都可以。下面我们通过这个锁屏、解锁相关的BroadcastReceiver来了解一下。

package cn.panghu.activitys;import com.example.broadcastsappdemo.R;import android.app.Activity;import android.app.KeyguardManager;import android.app.KeyguardManager.KeyguardLock;import android.content.BroadcastReceiver;import android.content.Context;import android.content.Intent;import android.content.IntentFilter;import android.os.Bundle;import android.os.PowerManager;import android.util.Log;import android.view.View;import android.view.View.OnClickListener;import android.view.ViewGroup.LayoutParams;import android.widget.Button;import android.widget.LinearLayout;import android.widget.TextView;import android.widget.Toast;public class ScreenLockedActivity extends Activity{private ScreenBroadcastReceiver screenBroadcastReceiver = null;private Context context = null;private Button lockedScreenBtn = null;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);context = getApplicationContext();setContentView(R.layout.screen_lock_layout);}@Overrideprotected void onResume() {// TODO Auto-generated method stubsuper.onResume();//注册这个广播registerScreenBroadcastReceiver();}private void registerScreenBroadcastReceiver() {screenBroadcastReceiver = new ScreenBroadcastReceiver();IntentFilter intentFilter = new IntentFilter();intentFilter.addAction(Intent.ACTION_SCREEN_OFF);//当屏幕锁屏的时候触发intentFilter.addAction(Intent.ACTION_SCREEN_ON);//当屏幕解锁的时候触发intentFilter.addAction(Intent.ACTION_USER_PRESENT);//当用户重新唤醒手持设备时触发context.registerReceiver(screenBroadcastReceiver, intentFilter);Log.i("screenBR", "screenBroadcastReceiver注册了");}//重写广播class ScreenBroadcastReceiver extends BroadcastReceiver{@Overridepublic void onReceive(Context context, Intent intent) {String strAction = intent.getAction();if (Intent.ACTION_SCREEN_OFF.equals(strAction)){//屏幕锁屏Log.i("screenBR", "屏幕锁屏：ACTION_SCREEN_OFF触发");Toast.makeText(context, "锁屏了", Toast.LENGTH_SHORT).show();}else if (Intent.ACTION_SCREEN_ON.equals(strAction)){//屏幕解锁(实际测试效果，不能用这个来判断解锁屏幕事件)//【因为这个是解锁的时候触发，而解锁的时候广播还未注册】Log.i("screenBR", "屏幕解锁：ACTION_SCREEN_ON触发");Toast.makeText(context, "解锁了", Toast.LENGTH_SHORT).show();}else if (Intent.ACTION_USER_PRESENT.equals(strAction)){//屏幕解锁(该Action可以通过静态注册的方法注册)//在解锁之后触发的，广播已注册Log.i("screenBR", "屏幕解锁：ACTION_USER_PRESENT触发");Toast.makeText(context, "解锁了", Toast.LENGTH_SHORT).show();}else{//nothing}}}@Overrideprotected void onPause() {// TODO Auto-generated method stubsuper.onPause();context.unregisterReceiver(screenBroadcastReceiver);Log.i("screenBR", "screenBroadcastReceiver取消注册了");}}

LogCat结果图：

由于是静态注册的方式，所以大家可能会觉得那我要怎么让它长久地监听这锁屏、解锁屏幕的广播呢？

首先我们再次强调ACTION_SCREEN_ON和ACTION_SCREEN_OFF只能通过动态注册的方式（代码内context.register和unregister），而ACTION_USER_PRESENT则是动态、静态注册两种方式都可以。

那么我们的突破口便是：我们可以动态地注册一个关于屏幕解锁后（ACTION_USER_PRESENT）的广播者，并且在这个广播的onReceive方法中实现我们要做的一些操作。例如我们可以开启一个Service服务，用于注册我们所想要的这个Broadcast Receiver

1.在Service中定义receiver

[java] view plaincopy

1. private BroadcastReceiver mScreenFilterReceiver = new BroadcastReceiver() {  
2.     public void onReceive(Context context, Intent intent) {  
3.             if (intent.getAction().equals(Intent.ACTION_SCREEN_ON)) {  
4.                 //做要求的处理  
5.             }else if(intent.getAction().equals(Intent.ACTION_SCREEN_OFF)){
6. }  
7.     }  
8. };  

2.在Service的onCreate中定义IntentFilter及注册receiver

[java] view plaincopy

1. IntentFilter ScreenFilter = new IntentFilter();  
2. ScreenFilter.addAction(Intent.ACTION_SCREEN_ON);  
3. ScreenFilter.addAction(Intent.ACTION_SCREEN_OFF); 
   
4. registerReceiver(mScreenFilterReceiver, ScreenFilter);  

3.在Service的onDestroy中要反注册这个receiver。

[java] view plaincopy

1. unregisterReceiver(mScreenFilterReceiver);  
2.