判断Android程序是否在前台的两种方法

    @Override
    protected void onStop() {
        if (!isAppOnForeground()) {
            Debug.i("dwy", "enter background");
            mIsBackground = true;
        } else {
            Debug.i("dwy", "foreground");
            mIsBackground = false;
        }
}

Judge is App in background when onStop() get called.

 public boolean isAppOnForeground() {
        // Returns a list of application processes that are running on the
        // device

        ActivityManager activityManager = (ActivityManager) getApplicationContext().getSystemService(Context.ACTIVITY_SERVICE);
        String packageName = getApplicationContext().getPackageName();

        List appProcesses = activityManager
                .getRunningAppProcesses();
        if (appProcesses == null)
            return false;

        for (ActivityManager.RunningAppProcessInfo appProcess : appProcesses) {
            // The name of the process that this object is associated with.
            if (appProcess.processName.equals(packageName)
                    && appProcess.importance == ActivityManager.RunningAppProcessInfo.IMPORTANCE_FOREGROUND) {
                return true;
            }
        }
        return false;
    }

方法二：

 /**
     * 需要权限:android.permission.GET_TASKS
     *
     * @param context
     * @return
     */
    public boolean isApplicationBroughtToBackground(Context context) {
        ActivityManager am = (ActivityManager) context
                        .getSystemService(Context.ACTIVITY_SERVICE);
        List tasks = am.getRunningTasks(1);
        if (tasks != null && !tasks.isEmpty()) {
            ComponentName topActivity = tasks.get(0).topActivity;
            Debug.i(TAG, "topActivity:" + topActivity.flattenToString());
            Debug.f(TAG, "topActivity:" + topActivity.flattenToString());
            if (!topActivity.getPackageName().equals(context.getPackageName())) {
                return true;
            }
        }
        return false;
    }