Broadcast广播

注册BroadcastReceiver有两种方法：在AndroidManifest.xml文件中进行注册；在应用程序的代码中进行注册（推荐）。

第一种方法，应用程序退出，系统仍然能匹配到Action，用户体验很不好。

1 BroadcastReceiver

1.1 Broadcast Receiver广播接收器

它和事件处理机制类似，只不过事件处理机制是程序组件级别，而广播事件机制是系统级别的。

BroadcastReceiver对象仅在调用onReceiver()方法时有效，当该方法执行完毕后，系统会销毁该对象。

1.2 使用Broadcast Receiver

①编写类继承BroadcastReceiver，复写onReceiver()方法

public class MyBroadcastReceiver extends BroadcastReceiver {

	
	private static final String TAG = "MyBroadcastReceiver";

	@Override
	public void onReceive(Context arg0, Intent arg1) {
		Log.i(TAG, "onReceive");
	}

}

②在AndroidManifest.xml文件中注册BroadcastReceiver

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

③构建Intent对象，调用sendBroadcast()方法，发送广播

public class MainActivity extends Activity {

	
    protected static final String ACTION = "com.example.broadcast.Action";

	@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        Button broadcastBtn = (Button) findViewById(R.id.startBtn);
        broadcastBtn.setOnClickListener(new Button.OnClickListener() {
			
			@Override
			public void onClick(View v) {
				Intent intent = new Intent();
				intent.setAction(ACTION);
				sendBroadcast(intent);
			}
		});
        
    }

}

1.3 使用Broadcast发送短信广播

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

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="18" />
	<uses-permission android:name="android.permission.RECEIVE_SMS"/>   <!-- 关键 -->
    
    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.example.broadcast.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.broadcast.MyBroadcastReceiver">
            <intent-filter>
                <action android:name="android.provider.Telephony.SMS_RECEIVED"/>  <!-- 关键 -->
            </intent-filter>
        </receiver>
    </application>
</manifest>

BroadcastReceiver.java:

package com.example.broadcast;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.telephony.gsm.SmsMessage;
import android.util.Log;

public class MyBroadcastReceiver extends BroadcastReceiver {

	
	private static final String TAG = "MyBroadcastReceiver";

	@Override
	public void onReceive(Context context, Intent intent) {
		Log.i(TAG, "onReceive");
		
		// 接受Intent对象中的数据
		Bundle bundle = intent.getExtras();
		// 在Bundle对象中有一个pdus属性，属性值为一个object数组
		Object[] myOBJpdus = (Object[]) bundle.get("pdus");
		// 创建一个SmsMessage类型的数组
		SmsMessage[] messages = new SmsMessage[myOBJpdus.length];
		Log.i(TAG, messages.length+"");
		for(int i=0; i<myOBJpdus.length; i++) {
			// 使用Object数组中的对象创建SmsMessage对象
			messages[i] = SmsMessage.createFromPdu((byte[])myOBJpdus[i]);
			// 调用SmsMessage对象的getDisppalyMessageBody()方法，就可以得到消息的内容
			Log.i(TAG, messages[i].getDisplayMessageBody());
		}
	}

}

2 在应用程序代码中进行注册实现BroadcastReceiver

注册BroadcastReceiver：registerReceiver()

取消注册BroadcastReceiver：unregisterReceiver()

Activity中的实现：(其他部分与上面类似，androidManifest.xml中不再需要注册)

((Button)findViewById(R.id.registerBtn)).setOnClickListener(new Button.OnClickListener() {
	@Override
	public void onClick(View v) {
		if(myReceiver==null) {
			myReceiver = new MyBroadcastReceiver();
		}
		IntentFilter filter = new IntentFilter();
		filter.addAction(ACTION);
		registerReceiver(myReceiver, filter);
		}
});
((Button)findViewById(R.id.unregisterBtn)).setOnClickListener(new Button.OnClickListener() {
	@Override
	public void onClick(View v) {
		if(myReceiver!=null) {
			unregisterReceiver(myReceiver);
		}
	}
});