Android基本之Broadcast Receiver

1、Broadcast Receiver簡介
2、Broadcast Receiver接收定時發送的廣播
3、自定義廣播

一、Broadcast Receiver簡介

Intent是一個對動作和行爲的抽象描述，負責組件之間程序之間進行消息傳遞。那麼Broadcast Receiver組件就提供了一種把Intent作爲一個消息廣播出去，由所有對其感興趣的程序對其作出反應的機制。

可以使用BroadcastReceiver使應用程序代碼能夠響應外部事件，如電話呼入、數據網絡可用等。儘管BroadcastReceiver可以使用NotificationManager來提醒用戶一些感興趣的事件的發生，但是它並不顯示用戶界面。

BroadcastReceiver在AndroidManifest.xml中完成註冊，也可以在代碼中通過Context.registerReceiver()方法完成註冊。

應用程序也可以通過Context.sendBroadcast()將自身的intent 廣播給其他應用程序。

二、Broadcast Receiver接收定時發送的廣播

做一個例子，功能是接收定時發送的廣播。

 

1、建立OneShotAlarm.java 內容如下：

package com.example.android.apis.app; import android.content.Context; import android.content.Intent; import android.content.BroadcastReceiver; import android.widget.Toast; // Need the following import to get access to the app resources, since this // class is in a sub-package. import com.example.android.apis.R; /** * This is an example of implement an {@link BroadcastReceiver} for an alarm that * should occur once. * <p> * When the alarm goes off, we show a <i>Toast</i>, a quick message. */ public class OneShotAlarm extends BroadcastReceiver { @Override public void onReceive(Context context, Intent intent) { Toast.makeText(context, R.string.one_shot_received, Toast.LENGTH_SHORT).show(); } }

2、在AndroidManifest.xml中註冊此Receiver ：

<receiver android:name=".app.OneShotAlarm" android:process=":remote" />

3.在Activity中啓動定時發送

// When the alarm goes off, we want to broadcast an Intent to our // BroadcastReceiver. Here we make an Intent with an explicit class // name to have our own receiver (which has been published in // AndroidManifest.xml) instantiated and called, and then create an // IntentSender to have the intent executed as a broadcast. Intent intent = new Intent(AlarmController.this, OneShotAlarm.class); PendingIntent sender = PendingIntent.getBroadcast(AlarmController.this, 0, intent, 0); // We want the alarm to go off 30 seconds from now. Calendar calendar = Calendar.getInstance(); calendar.setTimeInMillis(System.currentTimeMillis()); calendar.add(Calendar.SECOND, 30); // Schedule the alarm! AlarmManager am = (AlarmManager)getSystemService(ALARM_SERVICE); am.set(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(), sender);

三、自定義廣播

1.發送廣播

 

 //定義一個intent Intent intent = new Intent().setAction( "myAction").putExtra("myTag", "myData"); //廣播出去 sendBroadcast(intent);

2.在AndroidManifest.xml中註冊此Receiver

<receiver android:name="MyBroadReciever"> <intent -filter=""> <action android:name="myAction"> </action></intent> </receiver>

3.編輯Receiver

package android.example; import android.content.BroadcastReceiver; import android.content.Context; import android.content.Intent; import android.media.MediaPlayer; import android.util.Log; public class MyBroadReciever extends BroadcastReceiver { //如果接收的事件發生 @Override public void onReceive(Context context, Intent intent) { //對比Action決定輸出什麼信息 if(intent.getAction().equals("myAction")){ Log.v("MyBroadReciever", "onReceive"); } } }