android判断应用是否已经启动的实例

 /**
 * 判断应用是否已经启动
 *
 * @param context   上下文对象
 * @param packageName 要判断应用的包名
 * @return boolean
 */
public static boolean isAppAlive(Context context, String packageName) {
  ActivityManager activityManager =
      (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
  List<ActivityManager.RunningAppProcessInfo  processInfos
      = activityManager.getRunningAppProcesses();
  for (int i = 0; i < processInfos.size(); i++) {
    if (processInfos.get(i).processName.equals(packageName)) {
        return true;
    }
  }

  return false;
}

/**
 * 判断当前应用是否启动
 *
 * @param context
 * @return
 */
public static boolean getCurrentTask(Context context) {
	ActivityManager activityManager = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
	//获取当前所有存活task的信息
	List<RunningTaskInfo  appProcessInfos = activityManager.getRunningTasks(Integer.MAX_VALUE);
	//遍历，若task的name与当前task的name相同，则返回true，否则，返回false
	for (RunningTaskInfo process : appProcessInfos) {
		if (process.baseActivity.getPackageName().equals(context.getPackageName())
				|| process.topActivity.getPackageName().equals(context.getPackageName())) {
			return true;
		}
	}
	return false;
}
 
/**
 * 返回app运行状态
 *
 * @param context 一个context
 * @return int 1:前台 2:后台 0:不存在
 */
public static int isAppAlive(Context context) {
	String packageName = PackageUtil.getAppProcessName(context);
	ActivityManager activityManager = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
	List<ActivityManager.RunningTaskInfo  listInfos = activityManager.getRunningTasks(20);
	// 判断程序是否在栈顶
	if (listInfos.get(0).topActivity.getPackageName().equals(packageName)) {
		return 1;
	} else {
		// 判断程序是否在栈里
		for (ActivityManager.RunningTaskInfo info : listInfos) {
			if (info.topActivity.getPackageName().equals(packageName)) {
				return 2;
			}
		}
		return 0;// 栈里找不到，返回0
	}
}
 
 
/**
 * 判断某个界面是否在前台
 *
 * @param context
 * @param className 某个界面名称
 */
public static boolean isActivityForeground(Context context, String className) {
	if (context == null || TextUtils.isEmpty(className)) {
		return false;
	}
	ActivityManager am = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
	List<ActivityManager.RunningTaskInfo  list = am.getRunningTasks(1);
	if (list != null && list.size()   0) {
		ComponentName cpn = list.get(0).topActivity;
		if (className.equals(cpn.getClassName())) {
			return true;
		}
	}
	return false;
}