Broadcast Receiver接收并处理自定义Action广播通知
Broadcast Receiver用于接收并处理广播通知(broadcast announcements)。多数的广播是系统发起的，如地域变换、电量不足、来电来信等。程序也可以播放一个广播。程序可以有任意数量的 broadcast receivers来响应它觉得重要的通知。broadcast receiver可以通过多种方式通知用户：启动activity、使用NotificationManager、开启背景灯、振动设备、播放声音等，最典型的是在状态栏显示一个图标，这样用户就可以点它打开看通知内容。
通常我们的某个应用或系统本身在某些事件(电池电量不足、来电来短信)来临时会广播一个Intent出去，我们可以利用注册一个Broadcast Receiver来监听到这些Intent并获取Intent中的数据。
1. 我们自己的程序主动广播Intent
Java代码
final String BROADCAST = "com.forrest.action.mybroadcast";
Intent intent = new Intent(BROADCAST); // 对应setAction()
intent.putExtra("data_title", "来短信啦");
intent.putExtra("data_text", "美女你好，晚上可有空");
sendBroadcast(intent);
final String BROADCAST = "com.forrest.action.mybroadcast"; Intent intent = new Intent(BROADCAST); // 对应setAction() intent.putExtra("data_title", "来短信啦"); intent.putExtra("data_text", "美女你好，晚上可有空"); sendBroadcast(intent);
2.接收广播
接收broadcast需要注册一个Broadcast Receiver，并且要注册一个Intent Filter来制定Broadcase Receiver是对哪些Intent进行监听。
(1)注册Broadcast Receiver
一个Broadcast receiver只有一个简单的回调函数：onReceive(Context curContext, Intent broadcastMsg)，当一个广播消息被Receiver监听到时，Android会调用它的onReceive()方法，并将包含消息的Intent对象传给它。onReceive中代码的执行时间不要超过5s，否则android会弹出超时dialog。 此时是否另开一个线程来处理耗时的操作呢?
Receiver只在onReceive方法执行时是激活状态，只要onReceive一返回，Receiver就不再是激活状态了。Receiver进程是被一个激活状态的broadcast receiver所保护而不被系统终止的，一旦onReceive返回，Receiver进程broadcast receiver所保护而变为一个空进程，空进程是可以在任意时刻被终止的。这就带来了一个问题：当响应一个广播信息的处理十分耗时的时候，那么就应该把这个处理放在一个单独的线程里去执行，来保证主线程里的其他用户交互组件能够继续运行，而一旦这么做，当onReceive()唤起一个线程后就会马上返回，这时就会把Receiver进程放到被终止的境地。解决这个问题的方案是在onReceive()里开始一个Service，让这个Service去做这件事情，那么系统就会认为这个进程里还有活动正在进行。
(2)注册/注销Broadcast Receiver
1)在AndroidManifest.xml中注册
Xml代码
2)在代码中注册
Java代码
IntentFilter filter = new IntentFilter("com.forrest.action.mybroadcast"); // 和广播中Intent的action对应
MyBroadcastReceiver br = new MyBroadcastReceiver();
registerReceiver(new MyBroadcastReceiver(), filter);
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IntentFilter filter = new IntentFilter("com.forrest.action.mybroadcast"); // 和广播中Intent的action对应 MyBroadcastReceiver br = new MyBroadcastReceiver(); registerReceiver(new MyBroadcastReceiver(), filter);
3)注销
Java代码
unregisterReceiver(br);
unregisterReceiver(br);
3. 示例代码
Java代码
public class Receiver1 extends BroadcastReceiver {
private Context context;
public static final int NOTIFICATION_ID = 10001;
public void onReceive(Context context, Intent intent) {
this.context = context;
showNotification();
}
private void showNotification() {
Notification notification = new Notification(R.drawable.icon, "来电话啦...", System.currentTimeMillis());
PendingIntent contentIntent = PendingIntent.getActivity(context, 0, new Intent(context, MainActivity.class), 0);
notification.setLatestEventInfo(context, "来电话啦...嘿嘿", "赶紧接电话，否则误大事了", contentIntent);
NotificationManager notificationManager = (NotificationManager) context.getSystemService(
android.content.Context.NOTIFICATION_SERVICE);
notificationManager.notify(NOTIFICATION_ID, notification);
}
}
public class Receiver1 extends BroadcastReceiver { private Context context; public static final int NOTIFICATION_ID = 10001; public void onReceive(Context context, Intent intent) { this.context = context; showNotification(); } private void showNotification() { Notification notification = new Notification(R.drawable.icon, "来电话啦...", System.currentTimeMillis()); PendingIntent contentIntent = PendingIntent.getActivity(context, 0, new Intent(context, MainActivity.class), 0); notification.setLatestEventInfo(context, "来电话啦...嘿嘿", "赶紧接电话，否则误大事了", contentIntent); NotificationManager notificationManager = (NotificationManager) context.getSystemService( android.content.Context.NOTIFICATION_SERVICE); notificationManager.notify(NOTIFICATION_ID, notification); } }
Java代码
public class Receiver2 extends BroadcastReceiver {
private Context context;
@Override
public void onReceive(Context context, Intent intent) {
this.context = context;
deleteNotification();
}
private void deleteNotification() {
NotificationManager notificationManager = (NotificationManager) context.getSystemService(android.content.Context.NOTIFICATION_SERVICE);
notificationManager.cancel(Receiver1.NOTIFICATION_ID);
}
}
public class Receiver2 extends BroadcastReceiver { private Context context; @Override public void onReceive(Context context, Intent intent) { this.context = context; deleteNotification(); } private void deleteNotification() { NotificationManager notificationManager = (NotificationManager) context.getSystemService(android.content.Context.NOTIFICATION_SERVICE); notificationManager.cancel(Receiver1.NOTIFICATION_ID); } }
Java代码
public class MainActivity extends Activity {
private final String ACTION_SEND = "com.forrest.action.SENDMESSAGE",
ACTION_CLEAR = "com.forrest.action.CLEARNOTIFICATION";
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
( (Button) findViewById(R.id.btn1) ).setOnClickListener(new OnClickListener() {
public void onClick(View v) {
clickMenuItem(ACTION_SEND);
}
});
( (Button) findViewById(R.id.btn2) ).setOnClickListener(new OnClickListener() {
public void onClick(View v) {
clickMenuItem(ACTION_CLEAR);
}
});
}
private void clickMenuItem(final String action) {
Intent intent = new Intent(action);
sendBroadcast(intent);
}
}
public class MainActivity extends Activity { private final String ACTION_SEND = "com.forrest.action.SENDMESSAGE", ACTION_CLEAR = "com.forrest.action.CLEARNOTIFICATION"; public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); ( (Button) findViewById(R.id.btn1) ).setOnClickListener(new OnClickListener() { public void onClick(View v) { clickMenuItem(ACTION_SEND); } }); ( (Button) findViewById(R.id.btn2) ).setOnClickListener(new OnClickListener() { public void onClick(View v) { clickMenuItem(ACTION_CLEAR); } }); } private void clickMenuItem(final String action) { Intent intent = new Intent(action); sendBroadcast(intent); } }
注册Broadcast Reciver
Xml代码
android:label="@string/app_name">