Android判斷當前應用是否在前台運行

package cn.testforeground;
import java.util.List;
import android.os.Bundle;
import android.app.Activity;
import android.app.ActivityManager;
import android.app.ActivityManager.RunningTaskInfo;
import android.content.ComponentName;
import android.content.Context;
/**
 * Demo描述:
 * 判斷當前應用是否在前台運行
 * 
 * 注意權限:
 *  <uses-permission android:name ="android.permission.GET_TASKS" />
 */
public class MainActivity extends Activity {

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		isRunningForeground();
	}

	public boolean isRunningForeground(){
		String packageName=getPackageName(this);
		String topActivityClassName=getTopActivityName(this);
		System.out.println("packageName="+packageName+",topActivityClassName="+topActivityClassName);
		if (packageName!=null&&topActivityClassName!=null&&topActivityClassName.startsWith(packageName)) {
			System.out.println("---> isRunningForeGround");
			return true;
		} else {
			System.out.println("---> isRunningBackGround");
			return false;
		}
	}
	
	
	public  String getTopActivityName(Context context){
		String topActivityClassName=null;
		 ActivityManager activityManager =
		(ActivityManager)(context.getSystemService(android.content.Context.ACTIVITY_SERVICE )) ;
	     List<RunningTaskInfo> runningTaskInfos = activityManager.getRunningTasks(1) ;
	     if(runningTaskInfos != null){
	    	 ComponentName f=runningTaskInfos.get(0).topActivity;
	    	 topActivityClassName=f.getClassName();
	     }
	     return topActivityClassName;
	}
	
	public String getPackageName(Context context){
		 String packageName = context.getPackageName();  
		 return packageName;
	}
}

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="判斷當前應用是否在前台運行"
        android:layout_centerInParent="true"
        android:textSize="20sp"
     />

</RelativeLayout>