• 判斷APP是否在前臺運行
• 將APP切換到前臺

1. 判斷APP是否在前臺運行

 public static boolean isRunningForeground(Context context) {
        ActivityManager activityManager = (ActivityManager)context.getSystemService(Context.ACTIVITY_SERVICE);
        List<ActivityManager.RunningAppProcessInfo> appProcessInfos = activityManager.getRunningAppProcesses();
        // 枚舉進程
        for (ActivityManager.RunningAppProcessInfo appProcessInfo : appProcessInfos) {
            if (appProcessInfo.importance == ActivityManager.RunningAppProcessInfo.IMPORTANCE_FOREGROUND) {
                if (appProcessInfo.processName.equals(context.getApplicationInfo().processName)) {
                    return true;
                }
            }
        }
        return false;
    }

2. 將APP切換到前臺

//如果APP是在后臺運行
            if (!AllUtils.isRunningForeground(this)) {
                //獲取ActivityManager
                ActivityManager mAm = (ActivityManager) getSystemService(ACTIVITY_SERVICE);
                //獲得當前運行的task
                List<ActivityManager.RunningTaskInfo> taskList = mAm.getRunningTasks(100);
                for (ActivityManager.RunningTaskInfo rti : taskList) {
                    //找到當前應用的task，并啟動task的棧頂activity，達到程序切換到前臺
                    if (rti.topActivity.getPackageName().equals(getPackageName())) {
                        mAm.moveTaskToFront(rti.id, 0);
                        return;
                    }
                }
                //若沒有找到運行的task，用戶結束了task或被系統(tǒng)釋放，則重新啟動mainactivity
                Intent resultIntent = new Intent(MainActivity.this, MainActivity.class);
                resultIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_SINGLE_TOP);
                startActivity(resultIntent);
            }

3. 必須添加的權限

<!--前后臺的切換-->
    <uses-permission android:name="android.permission.GET_TASKS"/>
    <uses-permission android:name="android.permission.INTERACT_ACROSS_USERS_FULL"/>
    <uses-permission android:name="android.permission.GET_TOP_ACTIVITY_INFO"/>
    <uses-permission android:name="android.permission.REORDER_TASKS"/>

4.

5.

6.

7.

8.