Service联合Broadcase更新UI
在Android中，异步更新UI，通常我们会选用Handler启动线程，或者sendMessage的方式，那么利用Service和广播也可以更新UI的，例子如下：
我们建立一个Service：
package com.andy
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("wyf.wpf.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("wyf.wpf.Sample_3_6");
????????????????????????????????????????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 == Sample_3_6.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();
????????}????????
}
建立一个activity
package com.andy;//声明包语句
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 Sample_3_6 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(Sample_3_6.this, wyf.wpf.MyService.class);
????????????????????????????????Sample_3_6.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();
????????}
}
