Android_BroadcastReceiver详解

一、概述：

Android系统的四大组件之一BroadcastReceiver本质上就是一种全局监听器，用于监听系统全局的广播。

二、简介：

BroadcastReceiver用于接收程序所发出的Broadcast Intent，过程如下：

1.创建启动BroadcastReceiver的Intent。

2.调用Context的sendBroadcast()或者sendOrdereBroadcast()方法来启动指定的BroadcastReceiver。

①发送自定义广播：

public class MainActivity extends Activity {private Button button;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        button = (Button) findViewById(R.id.button1);        button.setOnClickListener(new OnClickListener(){@Overridepublic void onClick(View v) {// TODO 自动生成的方法存根Intent intent = new Intent();intent.setAction("com.example.blogbroadcastreceiver.husheng");intent.putExtra("husheng", "hello BroadcastReceiver !");sendBroadcast(intent);}                });    }

public class MyBroadcastReceiver extends BroadcastReceiver {@Overridepublic void onReceive(Context context, Intent intent) {// TODO 自动生成的方法存根Toast.makeText(context, intent.getAction()+"\n"+intent.getStringExtra("husheng"), Toast.LENGTH_LONG).show();}}

<receiver android:name=".MyBroadcastReceiver">    <intent-filter >        <action android:name="com.example.blogbroadcastreceiver.husheng"/>    </intent-filter>            </receiver>

②发送有序广播：

public class MainActivity extends Activity {private Button button;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        button = (Button) findViewById(R.id.button1);        button.setOnClickListener(new OnClickListener(){@Overridepublic void onClick(View v) {// TODO 自动生成的方法存根Intent intent = new Intent();intent.setAction("com.example.blogbroadcastreceiver.husheng");intent.putExtra("husheng", "hello BroadcastReceiver !");sendOrderedBroadcast(intent,null);}                });    }}

public class MyBroadcastReceiver extends BroadcastReceiver {@Overridepublic void onReceive(Context context, Intent intent) {// TODO 自动生成的方法存根Toast.makeText(context, "first\n"+intent.getStringExtra("husheng"), Toast.LENGTH_LONG).show();abortBroadcast();}}

public class anotherBroadcastReceiver extends BroadcastReceiver {@Overridepublic void onReceive(Context context, Intent intent) {// TODO 自动生成的方法存根Toast.makeText(context, "second\n"+intent.getStringExtra("husheng"), Toast.LENGTH_LONG).show();}}

<receiver android:name=".MyBroadcastReceiver">            <intent-filter android:priority="100">                <action android:name="com.example.blogbroadcastreceiver.husheng"/>            </intent-filter>                    </receiver>        <receiver android:name=".anotherBroadcastReceiver">            <intent-filter >                <action android:name="com.example.blogbroadcastreceiver.husheng"/>            </intent-filter>                    </receiver>

配置文件中，前一接收者中  android:priority="100" 保证它的优先级较高，先接收到广播。

没有加abortBroadcast()之前，两者都可以接收到广播，加了abortBroadcast()之后，阻断了广播，第二个接收者没有接收到广播。

三、深入：

使用本地广播：

public class MainActivity extends Activity {private IntentFilter intentFilter;private LocalReceiver localReceiver;private LocalBroadcastManager localBroadcastManager;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);localBroadcastManager = LocalBroadcastManager.getInstance(this);Button button = (Button) findViewById(R.id.button);button.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {Intent intent = new Intent("com.example.broadcasttest.LOCAL_BROADCAST");localBroadcastManager.sendBroadcast(intent);}});intentFilter = new IntentFilter();intentFilter.addAction("com.example.broadcasttest.LOCAL_BROADCAST");localReceiver = new LocalReceiver();localBroadcastManager.registerReceiver(localReceiver, intentFilter);}@Overrideprotected void onDestroy() {super.onDestroy();localBroadcastManager.unregisterReceiver(localReceiver);}class LocalReceiver extends BroadcastReceiver {@Overridepublic void onReceive(Context context, Intent intent) {Toast.makeText(context, "received local broadcast",Toast.LENGTH_SHORT).show();}}}

本地广播的优势：

1.安全，不会泄露数据。

2.高效。

四、总结：