java事件和监听器，执行不好？

Question

我目前正在根据下面发布的代码实现自定义事件和监听器。我被告知这是一个非常肮脏的实现，需要改变。但是，我对 java 和 android 很陌生，看不出当前的实现有什么问题。 我下面的方式有效，并且似乎也在做我需要的一切。我想知道是否有人可以看一下我的代码，并就我应该更改哪些内容以及我做错了什么提出一些建议。 以我的示例为例并对其进行修改，以便我可以看到您在谈论的内容不胜感激。

提前致谢!

/* SmartApp.java */
public class SmartApp extends Activity 
{
    private ConnectDevice cD = new ConnectDevice();
    private DataRobot dR = new DataRobot();
    private DataBuilder dB = new DataBuilder();
    private DataSender dS = new DataSender();
    public void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.intro);

    cD.addDataReceivedListener(new DataReceivedListener() {
        @Override
        public void dataReceivedReceived(DataReceivedEvent event) {
            // TODO Auto-generated method stub
            dR.analyzeData(event.getData());
        }
    });
    dR.addDataAnalyzedListener(new DataAnalyzedListener() {
        @Override
        public void dataAnalyzedReceived(DataAnalyzedEvent event) {
            // TODO Auto-generated method stub
            dB.submitData(event.getData());
        }
    });
    dB.addDataBuilderListener(new DataBuilderListener() {
        @Override
        public void dataBuilderReceived(DataBuilderEvent event) {
            // TODO Auto-generated method stub
            dS.sendData(event.getData());
        }
    });
      }
}  

<小时/>

/* ConnectDevice.java
 * This class is implementing runnable because i have a thread running that is checking
 * the contents of a socket. Irrelevant to events. */
public class ConnectDevice implements Runnable {

    private List _listeners = new ArrayList();
    private String data;

    /* Constructor */
    public ConnectDevice() {// does some socket stuff here, irrelevant to the events}
    public void run() {// does some socket stuff here, irrelevant to the events}

    public synchronized void addDataReceivedListener(DataReceivedListener listener) {
        _listeners.add(listener);
    }
    public synchronized void removeDataReceivedListener(DataReceivedListener listener) {
        _listeners.remove(listener);
    }
    private synchronized void fireDataReceivedEvent(String temp) {
        DataReceivedEvent dRE = new DataReceivedEvent(this, temp);
        Iterator listeners = _listeners.iterator();
        while(listeners.hasNext()) {
            ((DataReceivedListener)listeners.next()).dataReceivedReceived(dRE);
        }
    }
    public interface DataReceivedListener {
        public void dataReceivedReceived(DataReceivedEvent event);
    }
}  

<小时/>

/* DataRobot.java */
public class DataRobot {
    /* This class is for analyzing the data */
    private List _listeners = new ArrayList();
    private String data;
    public boolean analyzeData(String temp) {
        /* Analyze the data
         * This function analyzes the data, as explained in the OP
         * This function fires the analyzed data event when finished
             * analyzing the data.
         */
        data = temp;
        fireDataAnalyzedEvent(data); // this fires the dataanalyzedevent
        return true; //for now this will always return true
    }

    public synchronized void addDataAnalyzedListener(DataAnalyzedListener listener) {
        _listeners.add(listener);
    }
    public synchronized void removeDataAnalyzedListener(DataAnalyzedListener listener) {
        _listeners.remove(listener);
    }
    private synchronized void fireDataAnalyzedEvent(String temp) {
        DataAnalyzedEvent dRE = new DataAnalyzedEvent(this, temp);
        Iterator listeners = _listeners.iterator();
        while(listeners.hasNext()) {
            ((DataAnalyzedListener)listeners.next()).dataAnalyzedReceived(dRE);
        }
    }
    public interface DataAnalyzedListener {
        public void dataAnalyzedReceived(DataAnalyzedEvent event);
    }
}  

<小时/>

/* DataBuilder.java */
public class DataBuilder {
    private List _listeners = new ArrayList();
    private String data;
    public boolean submitData(String temp) {
            /* Builds the data
             * This function builds the data, as explained in the OP
             * This function fires the databuilder data event when finished
                     * building the data.
             */
        data = temp;
        fireDataBuilderEvent(data); //firing the databuilder event when finished
        return true;
    }
    public synchronized void addDataBuilderListener(DataBuilderListener listener) {
        _listeners.add(listener);
    }
    public synchronized void removeDataBuilderListener(DataBuilderListener listener) {
        _listeners.remove(listener);
    }
    private synchronized void fireDataBuilderEvent(String temp) {
        DataBuilderEvent dRE = new DataBuilderEvent(this, temp);
        Iterator listeners = _listeners.iterator();
        while(listeners.hasNext()) {
            ((DataBuilderListener)listeners.next()).dataBuilderReceived(dRE);
        }
    }
    public interface DataBuilderListener {
        public void dataBuilderReceived(DataBuilderEvent event);
    }
}  

<小时/>

/* DataSender.java */
/* this class has no event, because it is done firing events at this point */
public class DataSender {
    private String data;
    public boolean sendData(String temp) {
        data = temp;
        return true;
    }
}  

<小时/>

下面是每个事件的事件对象。我将其中的每一个都定义在一个单独的文件中，不确定这是否是一个好的过程。

/* DataReceivedEvent.java */
public class DataReceivedEvent extends EventObject{
    private String data;
    public DataReceivedEvent(Object source, String temp) {
        super(source);
        // TODO Auto-generated constructor stub
        data = temp;
    }
    public String getData() {
            // this function is just an accessor function
        return data;
    }
}  

<小时/>

/* DataAnalyzedEvent.java */
public class DataAnalyzedEvent extends EventObject{
    private String data;
    public DataAnalyzedEvent(Object source, String temp) {
        super(source);
        // TODO Auto-generated constructor stub
        data = temp;
    }
    public String getData() {
            // this function is just an accessor function
        return data;
    }
}  

<小时/>

/* DataBuilderEvent.java */
public class DataBuilderEvent extends EventObject {
    private String data;
    public DataBuilderEvent(Object source, String temp) {
        super(source);
        // TODO Auto-generated constructor stub
        data = temp;
    }
    public String getData() {
            // this function is just an accessor function
        return data;
    }
}

Answer 1

我不会说这是一个“非常肮脏的实现”。在我看来，使用回调/观察者/监听器是一个很好的做法。

当我编写 Android 应用程序时，我喜欢对其进行分层，这样“应用程序”就是普通的老式 Java，没有 Android 导入，并且理论上可以在 Swing 应用程序、基于 Java EE 的网站等中使用。 “部分是严格的用户界面。

我使用回调的目的是允许 Android 代码注册对应用程序中发生的事件的兴趣。例如，在二十一点游戏中，Activity 可能会调用 game.getDealer().playHand() 来告诉应用程序执行庄家玩牌逻辑。当该逻辑在应用程序中执行时，会触发诸如 cardDrawn(card)、cardFlipped(card)、handTotalChanged(handTotal) 等事件。应用程序的 Android 部分会监听这些并相应地在屏幕上重新绘制内容(但它对 Blackjack 一无所知)。

实际上，我只是让我的 Activity 实现 CardListener、HandListener 等接口(interface)，这样它们就可以直接接收事件(与您的操作方式不同)，但是您的风格不一定是坏方法。