intent 和 Broadcast Receiver之间的通信

工作原理是通过封装一个service启动的一个线程产生的随机数封装到intent对象传递给Activity，Activity接受到后讲结果输出到屏幕。

java的代码：

package jm.out;

import android.app.Activity;//引入相关包

import android.content.BroadcastReceiver;//引入相关包

import android.content.Context;//引入相关包

import android.content.Intent;//引入相关包

import android.content.IntentFilter;//引入相关包

import android.os.Bundle;//引入相关包

import android.view.View;//引入相关包

import android.view.View.OnClickListener;//引入相关包

import android.widget.Button;//引入相关包

import android.widget.TextView;//引入相关包

//继承自Activity的子类

public class IntentBroadcastActivity extends Activity {

public static final int CMD_STOP_SERVICE = 0;

Button btnStart;//开始服务Button对象应用

Button btnStop;//停止服务Button对象应用

TextView tv;//TextView对象应用

DataReceiver dataReceiver;//BroadcastReceiver对象

@Override

public void onCreate(Bundle savedInstanceState) {//重写onCreate方法

super.onCreate(savedInstanceState);

setContentView(R.layout.main);//设置显示的屏幕

btnStart = (Button)findViewById(R.id.btnStart);

btnStop = (Button)findViewById(R.id.btnStop);

tv = (TextView)findViewById(R.id.tv);

btnStart.setOnClickListener(new OnClickListener() {//为按钮添加点击事件监听

@Override

public void onClick(View v) {//重写onClick方法

Intent myIntent = new Intent(IntentBroadcastActivity.this, jm.out.MyService.class);

IntentBroadcastActivity.this.startService(myIntent);//发送Intent启动Service

}

});

btnStop.setOnClickListener(new OnClickListener() {//为按钮添加点击事件监听

@Override

public void onClick(View v) {//重写onClick方法

Intent myIntent = new Intent();//创建Intent对象

myIntent.setAction("wyf.wpf.MyService");

myIntent.putExtra("cmd", CMD_STOP_SERVICE);

sendBroadcast(myIntent);//发送广播

}

});

}

private class DataReceiver extends BroadcastReceiver{//继承自BroadcastReceiver的子类

@Override

public void onReceive(Context context, Intent intent) {//重写onReceive方法

double data = intent.getDoubleExtra("data", 0);

tv.setText("Service的数据为:"+data);

}

}

@Override

protected void onStart() {//重写onStart方法

dataReceiver = new DataReceiver();

IntentFilter filter = new IntentFilter();//创建IntentFilter对象

filter.addAction("wyf.wpf.Sample_3_6");

registerReceiver(dataReceiver, filter);//注册Broadcast Receiver

super.onStart();

}

@Override

protected void onStop() {//重写onStop方法

unregisterReceiver(dataReceiver);//取消注册Broadcast Receiver

super.onStop();

}

}

service类：

package jm.out;

import android.app.Service;//引入相关包

import android.content.BroadcastReceiver;//引入相关包

import android.content.Context;//引入相关包

import android.content.Intent;//引入相关包

import android.content.IntentFilter;//引入相关包

import android.os.IBinder;//引入相关包

//继承自Service的子类

public class MyService extends Service{

CommandReceiver cmdReceiver;

boolean flag;

@Override

public void onCreate() {//重写onCreate方法

flag = true;

cmdReceiver = new CommandReceiver();

super.onCreate();

}

@Override

public IBinder onBind(Intent intent) {//重写onBind方法

// TODO Auto-generated method stub

return null;

}

@Override

public int onStartCommand(Intent intent, int flags, int startId) {//重写onStartCommand方法

IntentFilter filter = new IntentFilter();//创建IntentFilter对象

filter.addAction("jm.out.MyService");

registerReceiver(cmdReceiver, filter);//注册Broadcast Receiver

doJob();//调用方法启动线程

return super.onStartCommand(intent, flags, startId);

}

//方法：

public void doJob(){

new Thread(){

public void run(){

while(flag){

try{//睡眠一段时间

Thread.sleep(1000);

}

catch(Exception e){

e.printStackTrace();

}

Intent intent = new Intent();//创建Intent对象

intent.setAction("jm.out.IntentBroadcastActivity");

intent.putExtra("data", Math.random());

sendBroadcast(intent);//发送广播

}

}

}.start();

}

private class CommandReceiver extends BroadcastReceiver{//继承自BroadcastReceiver的子类

@Override

public void onReceive(Context context, Intent intent) {//重写onReceive方法

int cmd = intent.getIntExtra("cmd", -1);//获取Extra信息

if(cmd == IntentBroadcastActivity.CMD_STOP_SERVICE){//如果发来的消息是停止服务

flag = false;//停止线程

stopSelf();//停止服务

}

}

}

@Override

public void onDestroy() {//重写onDestroy方法

this.unregisterReceiver(cmdReceiver);//取消注册的CommandReceiver

super.onDestroy();

}

}

xml配置：

<?xml version="1.0" encoding="utf-8" ?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

android:orientation="vertical" android:layout_width="fill_parent"

android:layout_height="fill_parent">

<Button android:id="@+id/btnStart"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:text="启动服务" />

<Button android:id="@+id/btnStop"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:text="停止服务" />

<TextView android:id="@+id/tv"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:text="等待来自Service的数据" />

</LinearLayout>

androidmanifest.xml的配置：

<?xml version="1.0" encoding="utf-8"?>

-<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="wyf.wpf" android:versionCode="1" android:versionName="1.0">

-<application android:icon="@drawable/icon"
android:label="@string/app_name">

-<activity android:name=".Sample_3_6"
android:label="@string/app_name">

-<intent-filter>

<action android:name="android.intent.action.MAIN" />

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

</intent-filter>

</activity>

-<service android:name=".MyService"
android:process=":remote">

-<intent-filter>

<actionandroid:name="wyf.wpf.MyService"
/>

</intent-filter>

</service>

</application>

<uses-sdk android:minSdkVersion="7" />

</manifest>

要注意的是红色代码，只有这样才可以让service在activity退出后还能运行，保证了主线程停止，service还能在后台运行。