Android 应用软件开发（十三）广播机制

广播机制：发送方不管接收方是否接收到数据，如何接收和处理

一、要想实现广播的接收，必须先创建一个类继承自BroadcastReceiver，复写其onReceive方法

二、在Manifest文件当中进行注册并设置action的过滤器，也可以在应用程序代码中注册

BroadcastReceiver的生命周期是，感兴趣的广播事件发生时创建对象，onReceive函数返回时销毁对象。

Intent 是action和data共同完成信息的携带的

如果BroadcastReceiver在Manifest中注册，则当应用程序关闭时，它依然会接收广播

<receiver android:name=".TestReceiver">
      <intent-filter>
           <action android:name="android.intent.action.EDIT"/>
      </intent-filter>
</receiver>

在代码中注册，用于更新UI，Activity启动时注册，不可见时取消注册

Android 系统中内置的BroadcastActions

这些内置的actions可以在帮助文档的Intent类的常量中查到

下面分别给出两个例子（在manifest文件中注册广播接收器和在代码中注册广播接收器）

注意如果在代码中注册，则必须先在manifest文件中设置权限

TestBCActivity.java:

package mars.testBC;

import android.app.Activity;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class TestBCActivity extends Activity {
    /** Called when the activity is first created. */
    private Button sendButton;
    private Button registerButton = null;
    private Button unregisterButton = null;
    private SMSReceiver smsReceiver = null;
    private static final String SMS_ACTION = "android.provider.Telephony.SMS_RECEIVED";
	@Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        sendButton = (Button)findViewById(R.id.sendButton);
        sendButton.setOnClickListener(new SendListener());
        registerButton = (Button)findViewById(R.id.registerButton);
        unregisterButton = (Button)findViewById(R.id.unregisterButton);
        registerButton.setOnClickListener(new RegisterListener());
        unregisterButton.setOnClickListener(new UnRegisterListener());
    }
	//例一
	class SendListener implements OnClickListener{

		@Override
		public void onClick(View v) {
			// TODO Auto-generated method stub
			//生成Intent对象，挟带广播信息
			Intent intent = new Intent();
			//设置Action
			intent.setAction(Intent.ACTION_EDIT);
			//广播
			TestBCActivity.this.sendBroadcast(intent);
		}
	}
	//例二
	class RegisterListener implements OnClickListener{

		@Override
		public void onClick(View v) {
			// TODO Auto-generated method stub
			smsReceiver = new SMSReceiver();
			//设置过滤器
			IntentFilter filter = new IntentFilter();
			//添加过滤事件（短消息接收事件）
			filter.addAction(SMS_ACTION);
			//注册广播接收器
			TestBCActivity.this.registerReceiver(smsReceiver, filter);
		}
	}
	class UnRegisterListener implements OnClickListener{

		@Override
		public void onClick(View v) {
			// TODO Auto-generated method stub
			//解除绑定
			TestBCActivity.this.unregisterReceiver(smsReceiver);
		}
	}
}

TestReceiver.java:

package mars.testBC;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;

public class TestReceiver extends BroadcastReceiver {

	public TestReceiver(){
		System.out.println("TestReceive");
	}
	@Override
	public void onReceive(Context arg0, Intent arg1) {
		// TODO Auto-generated method stub
		System.out.println("onReceive");
	}
}

SMSReceiver.java:

package mars.testBC;

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

public class SMSReceiver extends BroadcastReceiver {

	SMSReceiver(){
		System.out.println("SMSReceiver constructor");
	}
	@Override
	public void onReceive(Context context, Intent intent) {
		// TODO Auto-generated method stub
		Bundle bundle = intent.getExtras();
		Object[] myOBJpdus = (Object[])bundle.get("pdus");
		SmsMessage[] messages = new SmsMessage[myOBJpdus.length];
		System.out.println(messages.length);
		for(int i=0; i<myOBJpdus.length; i++)
		{
			messages[i] = SmsMessage.createFromPdu((byte[])myOBJpdus[i]);
			System.out.println(messages[i].getDisplayMessageBody());
		}
	}
}

main.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/hello" />

    <Button
        android:id="@+id/sendButton"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
    	android:text="start"/>
    
    <Button 
        android:id="@+id/registerButton"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="绑定"/>
    
    <Button 
        android:id="@+id/unregisterButton"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="解除绑定"/>
</LinearLayout>

Manifest.xml:

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

    <uses-sdk android:minSdkVersion="4" />

    <application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name" >
        <activity
            android:label="@string/app_name"
            android:name=".TestBCActivity" >
            <intent-filter >
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        
        <receiver android:name=".TestReceiver">
            <intent-filter>
                <action android:name="android.intent.action.EDIT"/>
            </intent-filter>
        </receiver>
    </application>
    <!-- 设置权限 -->
    <uses-permission 
            android:name="android.permission.RECEIVE_SMS">       
    </uses-permission>
</manifest>