Android判断程序前后台状态

AppStatusService
Java代码 
package org.wp.activity; 
 
import java.util.List; 
 
import android.app.ActivityManager; 
import android.app.ActivityManager.RunningAppProcessInfo; 
import android.app.Service; 
import android.content.Context; 
import android.content.Intent; 
import android.os.IBinder; 
import android.util.Log; 
 
public class AppStatusService extends Service { 
    private static final String TAG = "AppStatusService"; 
    private ActivityManager activityManager; 
    private String packageName; 
 
    @Override 
    public IBinder onBind(Intent intent) { 
        return null; 
    } 
 
    @Override 
    public int onStartCommand(Intent intent, int flags, int startId) { 
        activityManager = (ActivityManager) this.getSystemService(Context.ACTIVITY_SERVICE); 
        packageName = this.getPackageName(); 
        new Thread() { 
            public void run() { 
                try { 
                    while (true) { 
                        Thread.sleep(1000); 
                        if (isAppOnForeground()) { 
                            Log.i(TAG, "true"); 
                        } else { 
                            Log.i(TAG, "false"); 
                        } 
                    } 
                } catch (Exception e) {