Android判斷當前應用是否前臺應用

使用RunningAppProcessInfo來輪詢判斷，其中魅族手機遇到一個問題，其返回的狀態值和其他手機不一樣，做了下兼容：

    private boolean isAppBackground() {
        boolean isInBackground = true;
        String processName = "empty";
        ActivityManager am = (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);
        if (Build.VERSION.SDK_INT > Build.VERSION_CODES.KITKAT_WATCH) {
            List<ActivityManager.RunningAppProcessInfo> runningProcesses = am.getRunningAppProcesses();
            for (ActivityManager.RunningAppProcessInfo appProcess : runningProcesses) {
                if (appProcess.processName.equals(getPackageName())) {
                    processName = appProcess.processName;
                    Global.debug("-===1122====="+processName);
                    Global.debug("-===11223====="+appProcess.importance);

                    if (appProcess.importance == ActivityManager.RunningAppProcessInfo.IMPORTANCE_BACKGROUND) {
                        isInBackground = true;
                    } else if (appProcess.importance == ActivityManager.RunningAppProcessInfo.IMPORTANCE_PERCEPTIBLE_PRE_26) {
                        isInBackground = true;
                    } else {
                        isInBackground = false;
                    }
                }

            }
        } else {
            List<ActivityManager.RunningTaskInfo> taskInfo = am.getRunningTasks(1);
            ComponentName componentInfo = taskInfo.get(0).topActivity;
            if (componentInfo.getPackageName().equals(getPackageName())) {
                isInBackground = false;
            }
            Global.debug(componentInfo.getPackageName()+"==2==");
        }
        return isInBackground;
    }

AndroidProcess的五種狀態

Foreground 當前進程正在運行，可以接受觸點

Visible      當前進程正在運行，但是其他一些界面顯示在它之上，但是它是可見的

Service     當前進程包含服務正在運行

Background 當前進程在後臺運行

Empty      當前是空進程

Android源碼文檔中解釋

IMPORTANCE_BACKGROUND	this process process contains background code that is expendable.
IMPORTANCE_EMPTY	this process is empty of any actively running code.
IMPORTANCE_FOREGROUND	this process is running the foreground UI.
IMPORTANCE_SERVICE	this process is contains services that should remain running.
IMPORTANCE_VISIBLE	this process is running something that is actively visible to the user, though not in the immediate foreground.