【Android】Service通过广播更新UI

定义一个activity，在activity中定义一个内部广播接收器，并且动态注册该广播接收器：

package com.zzj.ui.serviceUpdateUIDemo;

import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.widget.TextView;

import com.zzj.ui.R;

public class MainActivity extends Activity {
private TextView textView;
public static final String ACTION_UPDATEUI = "action.updateUI";
UpdateUIBroadcastReceiver broadcastReceiver;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);

setContentView(R.layout.service_update_ui);
textView = (TextView) findViewById(R.id.count_txt);

// 动态注册广播
IntentFilter filter = new IntentFilter();
filter.addAction(ACTION_UPDATEUI);
broadcastReceiver = new UpdateUIBroadcastReceiver();
registerReceiver(broadcastReceiver, filter);

// 启动服务
Intent intent = new Intent(this, ServiceUpdateUI.class);
startService(intent);
}

/**
* 定义广播接收器（内部类）
*
* @author lenovo
*
*/
private class UpdateUIBroadcastReceiver extends BroadcastReceiver {

@Override
public void onReceive(Context context, Intent intent) {
textView.setText(String.valueOf(intent.getExtras().getInt("count")));
}

}

@Override
protected void onDestroy() {
System.out.println("onDestroy");
super.onDestroy();
// 注销广播
unregisterReceiver(broadcastReceiver);
}
}

activity布局文件：

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

<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="当前人数：" />

<TextView
android:id="@+id/count_txt"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />

</LinearLayout>

定义一个后台service，该service定时发送广播：

package com.zzj.ui.serviceUpdateUIDemo;

import java.util.Timer;
import java.util.TimerTask;

import android.app.Service;
import android.content.Intent;
import android.os.IBinder;

public class ServiceUpdateUI extends Service {
private Timer timer;
private TimerTask task;
private int count;

@Override
public IBinder onBind(Intent intent) {
return null;
}

@Override
public void onCreate() {
super.onCreate();

final Intent intent = new Intent();
intent.setAction(MainActivity.ACTION_UPDATEUI);

timer = new Timer();
task = new TimerTask() {

@Override
public void run() {
intent.putExtra("count", ++count);
sendBroadcast(intent);
}
};
timer.schedule(task, 1000, 1000);
}

@Override
public void onDestroy() {
super.onDestroy();
timer.cancel();
}

}

界面效果：



即使Activity退出再启动，仍然能通过广播接收器得到当前人数。