Android中BroadcastReceiver广播使用及注意点

android中的广播用途很广，是四大组件之一。在android中可以看到它的各种应用，从系统发出的广播，用户自定义的广播等。这里详细记录下广播的分类以及使用方法。广播，是由两方面组成一个流程：广播发送者、广播接收者。有以下场景：当网络状态发生变化时，系统（广播发送者）会发出一条广播，这条广播的标识是：android.net.conn.CONNECTIVITY_CHANGE。当开发人员（广播接收者）也添加了这个标识，那开发人员就可以在代码中接收到这条广播。广播接收者可以是多个。一、广播的分类，按有无顺序区分，可以分为：标准广播、有序广播。（1）标准广播。就是多个广播接收者，接收到广播是无序的，没有规定谁先谁后。按理想状况来说，是同一时间接收到系统发出的广播。（2）有序广播。在广播接收者，注册添加这条广播时，有增加了优先熟悉的设置。优先级高的先接收，优先级高的广播接收者，还可以控制是否将广播往下继续传递；二、广播的注册。根据注册方式不同有静态注册、动态注册。下面以接收系统广播为例：（1）静态注册：有两种方式实现：AndroidManifest.xml中注册+内部类；AndroidManifest.xml中注册+外部类。这两种的实现都是在AndroidManifest.xml中注册，在代码中写BroadCastReceive的重载即可。以下是，AndroidManifest.xml中注册+内部类：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.broadcasttest_csdn"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="18" />
<span style="color:#cc0000;"> <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/></span>
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.example.broadcasttest_csdn.MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />

<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<receiver android:name="com.example.broadcasttest_csdn.MainActivity$myBroadCast">
<intent-filter >
<action android:name="android.net.conn.CONNECTIVITY_CHANGE"/>
</intent-filter>
</receiver>
</application>

</manifest>

package com.example.broadcasttest_csdn;

import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.Bundle;
import android.R.anim;
import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.view.Menu;
import android.widget.Toast;

public class MainActivity extends Activity {

BroadcastReceiver bReceiver;
IntentFilter iFilter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
/*
iFilter=new IntentFilter();
iFilter.addAction(ConnectivityManager.CONNECTIVITY_ACTION);
bReceiver=new myBroadCast();
registerReceiver(bReceiver, iFilter);
*/
}
@Override
protected void onDestroy() {
// TODO Auto-generated method stub
super.onDestroy();
//unregisterReceiver(bReceiver);
}

public static  class myBroadCast extends BroadcastReceiver
{
@Override
public void onReceive(Context arg0, Intent arg1) {
// TODO Auto-generated method stub
ConnectivityManager connectivityManager=(ConnectivityManager)arg0.getSystemService(arg0.CONNECTIVITY_SERVICE);
NetworkInfo networkInfo=connectivityManager.getActiveNetworkInfo();
if(networkInfo!=null&&networkInfo.isAvailable())
{
Toast.makeText(arg0, "网络已连接", Toast.LENGTH_SHORT).show();
}
else {
Toast.makeText(arg0, "网络未连接", Toast.LENGTH_SHORT).show();
}
}
}

}

有几个要注意的地方：AndroidManifest.xml区域：权限需要添加，因为我们测试的是网络变化（这个系统变化最容易模拟）；receiver中的name不是activity的name，是BroadcastReceiver继承类的name。如果是内部类，则要像上方写法一样，用$来得到方法name；intent-filter中是要过滤下来的广播，就是你想要接收的广播标识。代码红字标识区域：广播接收的内部类，需要定义为static。否则会报错。那如果我不想把广播接收类写为内部类，我要写在外面，方便android工程的其他页面调用，可行吗？这个也是可以的，我们定义一个独立于activity的类，类名我们写为：BroadReceive。类的内容，如下：

package com.example.broadcasttest_csdn;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.widget.Toast;

public class BroadReceive extends BroadcastReceiver{

@Override
public void onReceive(Context paramContext, Intent paramIntent) {
// TODO Auto-generated method stub
ConnectivityManager connectivityManager=(ConnectivityManager)paramContext.getSystemService(paramContext.CONNECTIVITY_SERVICE);
NetworkInfo networkInfo=connectivityManager.getActiveNetworkInfo();
if(networkInfo!=null&&networkInfo.isAvailable())
{
Toast.makeText(paramContext, "网络已连接", Toast.LENGTH_SHORT).show();
}
else {
Toast.makeText(paramContext, "网络未连接", Toast.LENGTH_SHORT).show();
}

}

}

AndroidManifest.xml的定义如下：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.broadcasttest_csdn"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="18" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.example.broadcasttest_csdn.MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />

<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<receiver android:name="com.example.broadcasttest_csdn.BroadReceive">
<intent-filter >
<action android:name="android.net.conn.CONNECTIVITY_CHANGE"/>
</intent-filter>
</receiver>
</application>

</manifest>

与内部类方式相比，区别在上方receive的name，用的是外部类name。有些同学还会问，我如果在代码中，在activity类外，定义一个普通类继承BroadCastReceiver。能否在AndroidManifest.xml中静态注册。答案是不行的，你会发现，这里需要static标识，而这个类没办法加这个static标识。（2）动态注册。从上方的静态注册，我们看到还是有挺多要注意的，有的地方也不是很方便灵活。那我们可以考虑用动态注册。动态注册，除了权限外，我们不需要在AndroidManifest.xml中操作其他内容，其他的都在代码中实现；如下：

package com.example.broadcasttest_csdn;

import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.Bundle;
import android.R.anim;
import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.view.Menu;
import android.widget.Toast;

public class MainActivity extends Activity {

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

iFilter=new IntentFilter();
iFilter.addAction(ConnectivityManager.CONNECTIVITY_ACTION);
bReceiver=new myBroadCast();
registerReceiver(bReceiver, iFilter);

}
@Override
protected void onDestroy() {
// TODO Auto-generated method stub
super.onDestroy();
unregisterReceiver(bReceiver);
}

public static  class myBroadCast extends BroadcastReceiver
{
@Override
public void onReceive(Context arg0, Intent arg1) {
// TODO Auto-generated method stub
ConnectivityManager connectivityManager=(ConnectivityManager)arg0.getSystemService(arg0.CONNECTIVITY_SERVICE);
NetworkInfo networkInfo=connectivityManager.getActiveNetworkInfo();
if(networkInfo!=null&&networkInfo.isAvailable())
{
Toast.makeText(arg0, "网络已连接", Toast.LENGTH_SHORT).show();
}
else {
Toast.makeText(arg0, "网络未连接", Toast.LENGTH_SHORT).show();
}
}
}

}

AndroidManifest.xml的定义如下：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.broadcasttest_csdn"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="18" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.example.broadcasttest_csdn.MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />

<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>

</application>

</manifest>

如代码中几个步骤，定义过滤器intent-filter、定义广播接收类、在activity开启的时候绑定二者、在activity销毁的时候解除绑定。与静态注册相比，大家应该更习惯用动态注册。二、广播使用实例（1）标准广播。上方例子中接收系统广播，都可以算是标准广播。因为没有做优先级设置。为了更好的说明，我们发送自定义广播，并接收。

package com.example.broadcasttest_csdn;

import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.Bundle;
import android.R.anim;
import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.util.Log;
import android.view.Menu;
import android.widget.Toast;

public class MainActivity extends Activity {

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

iFilter=new IntentFilter();
iFilter.addAction("myAction");
bReceiver=new myBroadCast();
registerReceiver(bReceiver, iFilter);

Intent intent=new Intent();
intent.setAction("myAction");
intent.putExtra("info", "附带信息");
sendBroadcast(intent);

}
@Override
protected void onDestroy() {
// TODO Auto-generated method stub
super.onDestroy();
unregisterReceiver(bReceiver);
}

public static  class myBroadCast extends BroadcastReceiver
{
@Override
public void onReceive(Context arg0, Intent arg1) {
// TODO Auto-generated method stub
if(arg1!=null)
{
Log.i("Action", arg1.getAction()) ;
Log.i("获取的信息", arg1.getStringExtra("info"));
}
}
}

}

代码里没有做太多的修改。偷懒了，刚启动就先注册一个广播接收，然后直接就发送广播。你在onReceive里，可以收到广播的信息。Intent我们知道可以附带一些内容的，我也一起传了个值过去。（2）有序广播

package com.example.broadcasttest_csdn;

import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.Bundle;
import android.R.anim;
import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.util.Log;
import android.view.Menu;
import android.widget.Toast;

public class MainActivity extends Activity {

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

iFilter=new IntentFilter();
iFilter.addAction("myAction");

       iFilter.setPriority(100);
bReceiver=new myBroadCast();
registerReceiver(bReceiver, iFilter);

Intent intent=new Intent();
intent.setAction("myAction");
intent.putExtra("info", "附带信息");
sendOrderedBroadcast(intent, null);

}
@Override
protected void onDestroy() {
// TODO Auto-generated method stub
super.onDestroy();
unregisterReceiver(bReceiver);
}

public static  class myBroadCast extends BroadcastReceiver
{
@Override
public void onReceive(Context arg0, Intent arg1) {
// TODO Auto-generated method stub
if(arg1!=null)
{
Log.i("Action", arg1.getAction()) ;
Log.i("获取的信息", arg1.getStringExtra("info"));
abortBroadcast();
}
}
}

}

和以前的代码相比，唯二的区别就在发送广播和截断广播的地方。一个是order、abort，按字面意思就是按顺序和截断。这样的广播，到onReceive中就被截断了，不会再往下传递了。至于广播出来后，谁第一个接收，是根据优先级来的。100->99->98....，类似这样的。（3）本地广播这是刚漏了，补上这个的说明。本地广播和以上两个的区别在于：本地广播，只供本应用使用，有效的提高广播的安全性。写法与以往的写法没有太大的区别：

package com.example.broadcasttest_csdn;

import android.os.Bundle;
import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.support.v4.content.LocalBroadcastManager;
import android.util.Log;

public class MainActivity extends Activity {

LocalBroadcastManager localBroadcastManager;

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

iFilter=new IntentFilter();
iFilter.addAction("myAction");
iFilter.setPriority(100);
bReceiver=new myBroadCast();
//registerReceiver(bReceiver, iFilter);
localBroadcastManager=LocalBroadcastManager.getInstance(MainActivity.this);
localBroadcastManager.registerReceiver(bReceiver, iFilter);

Intent intent=new Intent();
intent.setAction("myAction");
intent.putExtra("info", "附带信息");
//sendOrderedBroadcast(intent, null);
localBroadcastManager.sendBroadcastSync(intent);
}
@Override
protected void onDestroy() {
// TODO Auto-generated method stub
super.onDestroy();
//unregisterReceiver(bReceiver);
localBroadcastManager.unregisterReceiver(bReceiver);
}

public static  class myBroadCast extends BroadcastReceiver
{
@Override
public void onReceive(Context arg0, Intent arg1) {
// TODO Auto-generated method stub
if(arg1!=null)
{
Log.i("Action", arg1.getAction()) ;
Log.i("获取的信息", arg1.getStringExtra("info"));
//abortBroadcast();
}
}
}

}

将原来的BroadCastReceiver替换，就是修改的地方。将有些定义注释，用local的定义替换。这就得到我们要的本地广播。以上，总结了我们会遇到的所有广播形式以及注册方式，仅供参考。广播就到这里。O 。