即使关闭应用程序，如何保持CountDownTimer运行? [英] How to keep a CountDownTimer running even if the app is closed?

问题描述

我度过了整个暑假，学习如何编码和构建自己的第一个应用程序(在android studio中).因此，我不是专家编码员.这周我遇到了一个问题.基本上，我正在开发一个测验应用程序，当用户输入错误答案时，他必须等待5分钟.事实是，当倒数计时器启动并且用户关闭应用程序时(我指的是关闭应用程序，将其销毁，而不仅仅是按下主页按钮)，倒数计时器将停止.我想知道即使关闭应用程序也如何保持计时器运行.您的帮助将不胜感激，如果你们给我一个示例代码，那将是非常棒的. 预先感谢！

I spent my summer learning how to code and building my first app (in android studio). Therefore I am not an expert coder. This week I encountered a problem. Basically, I am developing a quiz app and when the user gets the answer wrong he have to wait 5 min. The thing is that when the countdowntimer starts and the user closes the app (by closing the app I mean destroy it and not just push the home button) the countdowntimer stops. I am wondering how I can manage to keep the timer running even if the app is closed. Your help will be greatly appreciated and it would be fantastic if you guys give me a sample code. Thanks in advance!

推荐答案

以如下方式在服务中运行:在您的活动中使用创建广播接收器，并让该服务发送广播.

Run it in a service as such: use create a broadcast receiver in your activity and have the service send broadcasts.

package com.example.cdt;

import android.app.Service;
import android.content.Intent;
import android.os.CountDownTimer;
import android.os.IBinder;
import android.util.Log;

public class BroadcastService extends Service {

    private final static String TAG = "BroadcastService";

    public static final String COUNTDOWN_BR = "your_package_name.countdown_br";
    Intent bi = new Intent(COUNTDOWN_BR);

    CountDownTimer cdt = null;

    @Override
        public void onCreate() {       
            super.onCreate();

            Log.i(TAG, "Starting timer...");

            cdt = new CountDownTimer(30000, 1000) {
                @Override
                public void onTick(long millisUntilFinished) {

                    Log.i(TAG, "Countdown seconds remaining: " + millisUntilFinished / 1000);
                    bi.putExtra("countdown", millisUntilFinished);
                    sendBroadcast(bi);
                }

                @Override
                public void onFinish() {
                    Log.i(TAG, "Timer finished");
                }
            };

            cdt.start();
        }

        @Override
        public void onDestroy() {

            cdt.cancel();
            Log.i(TAG, "Timer cancelled");
            super.onDestroy();
        }

        @Override
        public int onStartCommand(Intent intent, int flags, int startId) {       
            return super.onStartCommand(intent, flags, startId);
        }

        @Override
        public IBinder onBind(Intent arg0) {       
            return null;
        }
}

主要活动中:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    startService(new Intent(this, BroadcastService.class));
    Log.i(TAG, "Started service");
}

private BroadcastReceiver br = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {            
        updateGUI(intent); // or whatever method used to update your GUI fields
    }
};

@Override  
public void onResume() {
    super.onResume();        
    registerReceiver(br, new IntentFilter(BroadcastService.COUNTDOWN_BR));
    Log.i(TAG, "Registered broacast receiver");
    }

@Override
public void onPause() {
    super.onPause();
    unregisterReceiver(br);
    Log.i(TAG, "Unregistered broacast receiver");
}

@Override
public void onStop() {
    try {
        unregisterReceiver(br);
    } catch (Exception e) {
        // Receiver was probably already stopped in onPause()
    }
    super.onStop();
}
@Override
public void onDestroy() {        
    stopService(new Intent(this, BroadcastService.class));
    Log.i(TAG, "Stopped service");
    super.onDestroy();
}

private void updateGUI(Intent intent) {
    if (intent.getExtras() != null) {
        long millisUntilFinished = intent.getLongExtra("countdown", 0);
        Log.i(TAG, "Countdown seconds remaining: " +  millisUntilFinished / 1000);            
    }
}

请注意，我从>如何在是Android中的服务?，我为自己的android countDownTimer对其进行了修改.

Note I got this code from How to run CountDownTimer in a Service in Android?, which I modified for my own android countDownTimer.

这篇关于即使关闭应用程序，如何保持CountDownTimer运行?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！