Android基本之Broadcast Receiver

1、Broadcast Receiver简介
2、Broadcast Receiver接收定时发送的广播
3、自定义广播

一、Broadcast Receiver简介

Intent是一个对动作和行为的抽象描述，负责组件之间程序之间进行消息传递。那么Broadcast Receiver组件就提供了一种把Intent作为一个消息广播出去，由所有对其感兴趣的程序对其作出反应的机制。

可以使用BroadcastReceiver使应用程序代码能够响应外部事件，如电话呼入、数据网络可用等。尽管BroadcastReceiver可以使用NotificationManager来提醒用户一些感兴趣的事件的发生，但是它并不显示用户界面。

BroadcastReceiver在AndroidManifest.xml中完成注册，也可以在代码中通过Context.registerReceiver()方法完成注册。

应用程序也可以通过Context.sendBroadcast()将自身的intent 广播给其他应用程序。

二、Broadcast Receiver接收定时发送的广播

做一个例子，功能是接收定时发送的广播。

1、建立OneShotAlarm.java 内容如下：

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1. packagecom.example.android.apis.app;
3. importandroid.content.Context;
4. importandroid.content.Intent;
5. importandroid.content.BroadcastReceiver;
6. importandroid.widget.Toast;
8. //Needthefollowingimporttogetaccesstotheappresources,sincethis
9. //classisinasub-package.
10. importcom.example.android.apis.R;
12. /**
13. *Thisisanexampleofimplementan{@linkBroadcastReceiver}foranalarmthat
14. *shouldoccuronce.
15. *<p>
16. *Whenthealarmgoesoff,weshowa<i>Toast</i>,aquickmessage.
17. */
18. publicclassOneShotAlarmextendsBroadcastReceiver
19. {
20. @Override
21. publicvoidonReceive(Contextcontext,Intentintent)
22. {
23. Toast.makeText(context,R.string.one_shot_received,Toast.LENGTH_SHORT).show();
24. }
25. }

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中注册此Receiver ：

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

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

3.在Activity中启动定时发送

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1. //Whenthealarmgoesoff,wewanttobroadcastanIntenttoour
2. //BroadcastReceiver.HerewemakeanIntentwithanexplicitclass
3. //nametohaveourownreceiver(whichhasbeenpublishedin
4. //AndroidManifest.xml)instantiatedandcalled,andthencreatean
5. //IntentSendertohavetheintentexecutedasabroadcast.
6. Intentintent=newIntent(AlarmController.this,OneShotAlarm.class);
7. PendingIntentsender=PendingIntent.getBroadcast(AlarmController.this,
8. 0,intent,0);
10. //Wewantthealarmtogooff30secondsfromnow.
11. Calendarcalendar=Calendar.getInstance();
12. calendar.setTimeInMillis(System.currentTimeMillis());
13. calendar.add(Calendar.SECOND,30);
15. //Schedulethealarm!
16. AlarmManageram=(AlarmManager)getSystemService(ALARM_SERVICE);
17. am.set(AlarmManager.RTC_WAKEUP,calendar.getTimeInMillis(),sender);

// 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、自定义广播

1.发送广播

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1. //定义一个intent
2. Intentintent=newIntent().setAction(
3. "myAction").putExtra("myTag",
4. "myData");
5. //广播出去
6. sendBroadcast(intent);

//定义一个intent Intent intent = new Intent().setAction( "myAction").putExtra("myTag", "myData"); //广播出去 sendBroadcast(intent);

2.在AndroidManifest.xml中注册此Receiver

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1. <receiverandroid:name="MyBroadReciever">
2. <intent-filter="">
3. <actionandroid:name="myAction">
4. </action></intent>
5. </receiver>

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

3.编辑Receiver

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1. packageandroid.example;
3. importandroid.content.BroadcastReceiver;
4. importandroid.content.Context;
5. importandroid.content.Intent;
6. importandroid.media.MediaPlayer;
7. importandroid.util.Log;
9. publicclassMyBroadRecieverextendsBroadcastReceiver{
11. //如果接收的事件发生
12. @Override
13. publicvoidonReceive(Contextcontext,Intentintent){
14. //对比Action决定输出什么信息
15. if(intent.getAction().equals("myAction")){
16. Log.v("MyBroadReciever","onReceive");
17. }
18. }
19. }