Android 判断应用前后台运行状态

1、通过RunningTaskInfo类判断（需要额外权限）：

private Timer mTimer = new Timer();
private TimerTask mTimerTask;

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    if (isApplicationBroughtToBackground(this)){
        Log.e("TAG", "onCreate: 11111111111111111" );
    }else {
        Log.e("TAG", "onCreate: 22222222222222222" );
    }
}


@Override
protected void onResume() {
    super.onResume();
    if (isApplicationBroughtToBackground(this)){
        Log.e("TAG", "onCreate: 11111111111111111" );
    }else {
        Log.e("TAG", "onCreate: 22222222222222222" );
    }
}

@Override
protected void onPause() {
    super.onPause();
    if (isApplicationBroughtToBackground(this)){
        Log.e("TAG", "onCreate: 11111111111111111" );
    }else {
        Log.e("TAG", "onCreate: 22222222222222222" );
    }
}

/**
 *判断当前应用程序处于前台还是后台
 */
public static boolean isApplicationBroughtToBackground(final Context context) {
    ActivityManager am = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
    List<ActivityManager.RunningTaskInfo> tasks = am.getRunningTasks(1);
    if (!tasks.isEmpty()) {
        ComponentName topActivity = tasks.get(0).topActivity;
        if (!topActivity.getPackageName().equals(context.getPackageName())) {
            return true;
        }
    }
    return false;
}

2、通过RunningAppProcessInfo类判断（不需要额外权限）：

public static boolean isBackground(Context context) {

    ActivityManager activityManager = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
    List<ActivityManager.RunningAppProcessInfo> appProcesses = activityManager.getRunningAppProcesses();
    for (ActivityManager.RunningAppProcessInfo appProcess : appProcesses) {
        if (appProcess.processName.equals(context.getPackageName())) {
            if (appProcess.importance == ActivityManager.RunningAppProcessInfo.IMPORTANCE_BACKGROUND) {
                Log.i("后台", appProcess.processName);
                return true;
            }else{
                Log.i("前台", appProcess.processName);
                return false;
            }
        }
    }
    return false;
}