特殊广播接收者

比如操作特别频繁的广播事件 屏幕的锁屏和解锁 电池电量的变化 这样的广播接收者在清单文件里面注册无效

import android.os.Bundle;
import android.app.Activity;
import android.content.IntentFilter;
import android.view.Menu;

public class MainActivity extends Activity {

private ScreenReceiver screenReceiver;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

/* <receiver android:name="com.itheima.screen.ScreenReceiver">
<intent-filter >
<action android:name="android.intent.action.SCREEN_OFF"/>
<action android:name="android.intent.action.SCREEN_ON"/>
</intent-filter>
</receiver>*/

//[1]动态的去注册屏幕解锁和锁屏的广播
screenReceiver = new ScreenReceiver();
//[2]创建intent-filter对象
IntentFilter filter = new IntentFilter();
//[3]添加要注册的action
filter.addAction("android.intent.action.SCREEN_OFF");
filter.addAction("android.intent.action.SCREEN_ON");
//[4]注册广播接收者
this.registerReceiver(screenReceiver, filter);

}

@Override
protected void onDestroy() {
//当activity销毁的时候  取消注册广播接收者
unregisterReceiver(screenReceiver);

super.onDestroy();
}

}

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;

public class ScreenReceiver extends BroadcastReceiver {

@Override
public void onReceive(Context context, Intent intent) {

//[1]获取到当前广播的事件类型
String action = intent.getAction();
//[2]对当前广播事件类型做一个判断

if ("android.intent.action.SCREEN_OFF".equals(action)) {

System.out.println("屏幕锁屏了");
}else if ("android.intent.action.SCREEN_ON".equals(action)) {

System.out.println("说明屏幕解锁了~~~");
}

}

}

当activity销毁的时候  取消注册广播接收者

09-08 07:25:42.239: E/ActivityThread(2173): Activity com.itheima.screen.MainActivity has leaked IntentReceiver com.itheima.screen.ScreenReceiver@b6486088 that was originally registered here. Are you missing a call to

unregisterReceiver()?