监视任务栈中最新打开的程序

import java.util.List;
import android.app.ActivityManager;
import android.app.ActivityManager.RunningTaskInfo;
import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.os.SystemClock;

/**
 * 看门狗服务
 * @author Administrator
 *
 */
public class WatchDogService extends Service {
    private boolean isWatch;//是否监控
    private ActivityManager am;
    @Override
    public IBinder onBind(Intent intent) {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public void onCreate() {
        am = (ActivityManager) getSystemService(ACTIVITY_SERVICE);
        watchDog();//看门狗的逻辑
        super.onCreate();
    }

    private void watchDog(){
        new Thread(){
            public void run() {
                isWatch = true;
                while (isWatch) {
                    //通过isWatch 来控制该线程
                    //时刻监控任务栈
                    List runningTasks = am.getRunningTasks(1);//获取最新的任务栈集合
                    RunningTaskInfo runningTaskInfo = runningTasks.get(0);//最新打开的任务栈（不管多少个栈，只看第一个）
                    //任务栈中获取顶部activity
                    String packName = runningTaskInfo.topActivity.getPackageName();
                    System.out.println(packName);

                    SystemClock.sleep(50);//每个50毫秒 狗监控任务栈
                }

            };
        }.start();
    }

    @Override
    public void onDestroy() {
        // TODO Auto-generated method stub
        isWatch = false;
        super.onDestroy();
    }
}

清单文件中注册服务：

<service android:name="com.lqr.service.WatchDogService">service>