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：

packagecom.example.android.apis.app;

importandroid.content.Context;
importandroid.content.Intent;
importandroid.content.BroadcastReceiver;
importandroid.widget.Toast;

//Needthefollowingimporttogetaccesstotheappresources,sincethis
//classisinasub-package.
importcom.example.android.apis.R;

/**
*Thisisanexampleofimplementan{@linkBroadcastReceiver}foranalarmthat
*shouldoccuronce.
*<p>
*Whenthealarmgoesoff,weshowa<i>Toast</i>,aquickmessage.
*/
publicclassOneShotAlarmextendsBroadcastReceiver
{
@Override
publicvoidonReceive(Contextcontext,Intentintent)
{
Toast.makeText(context,R.string.one_shot_received,Toast.LENGTH_SHORT).show();
}
}

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 ：

<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

//Whenthealarmgoesoff,wewanttobroadcastanIntenttoour
//BroadcastReceiver.HerewemakeanIntentwithanexplicitclass
//nametohaveourownreceiver(whichhasbeenpublishedin
//AndroidManifest.xml)instantiatedandcalled,andthencreatean
//IntentSendertohavetheintentexecutedasabroadcast.
Intentintent=newIntent(AlarmController.this,OneShotAlarm.class);
PendingIntentsender=PendingIntent.getBroadcast(AlarmController.this,
0,intent,0);

//Wewantthealarmtogooff30secondsfromnow.
Calendarcalendar=Calendar.getInstance();
calendar.setTimeInMillis(System.currentTimeMillis());
calendar.add(Calendar.SECOND,30);

//Schedulethealarm!
AlarmManageram=(AlarmManager)getSystemService(ALARM_SERVICE);
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

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

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

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

3.编辑Receiver

packageandroid.example;

importandroid.content.BroadcastReceiver;
importandroid.content.Context;
importandroid.content.Intent;
importandroid.media.MediaPlayer;
importandroid.util.Log;

publicclassMyBroadRecieverextendsBroadcastReceiver{

//如果接收的事件发生
@Override
publicvoidonReceive(Contextcontext,Intentintent){
//对比Action决定输出什么信息
if(intent.getAction().equals("myAction")){
Log.v("MyBroadReciever","onReceive");
}
}
}