判斷App整體處於前臺還是後臺

轉載請註明轉自：[noyet12的博客](http://blog.csdn.net/u012975705) 
博客原址：http://blog.csdn.net/u012975705/article/details/50109883

上篇博客說道，在項目中使用Notification，想要的效果是在app退出前臺工作時拉取後臺數據，發現新動態則在通知欄提示用戶。要達到這個效果，就必須判斷當前app是否處於前臺工作，下面給出判斷方法。

    public boolean isAppOnForeground() {
        ActivityManager activityManager = (ActivityManager) getApplicationContext().getSystemService(
                Context.ACTIVITY_SERVICE);
        String packageName =getApplicationContext().getPackageName();
        List<ActivityManager.RunningAppProcessInfo> appProcesses =  activityManager.getRunningAppProcesses();
        if (appProcesses == null) {
            return false;
        }
        for (ActivityManager.RunningAppProcessInfo appProcess : appProcesses) {
            if (appProcess.processName.equals(packageName)
                    && appProcess.importance == ActivityManager.RunningAppProcessInfo.IMPORTANCE_FOREGROUND) {
                return true;
            }
        }
        return false;
    }

使用方式：

 @Override
    protected void onStop() {
        super.onStop();
        if (MainApplication.getInstance().getIsLogin()
                && !MainApplication.getInstance().isAppOnForeground()) {
            mTask = new TimerTask() {
                @Override
                public void run() {
                    getNews();
                }
            };
            mTimer = new Timer();
            mTimer.schedule(mTask, 3 * 1000, 3 * 60 * 1000);
        }
    }