判断App整体处于前台还是后台

转载请注明转自：[noyet12的博客](http://blog.csdn.net/u012975705) 
博客原址：http://blog.csdn.net/u012975705/article/details/50109883

上篇博客说道，在项目中使用Notification，想要的效果是在app退出前台工作时拉取后台数据，发现新动态则在通知栏提示用户。要达到这个效果，就必须判断当前app是否处于前台工作，下面给出判断方法。

    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);
        }
    }