java - Java ActionListeners到独立类

有什么方法可以将actionListener类移动到独立类？

我以Java和MVC设计模式为例。我有3个按钮可以更改背景颜色。

这是模特

public class ChangeFontColorApplicationModel {
    public ChangeFontColorApplicationModel(){}
}

视图

import java.awt.event.*;
import javax.swing.*;

public class ChangeFontColorApplicationView extends JFrame{
private JButton changeToYellowButton = new JButton("Yellow font");
private JButton changeToBlackButton = new JButton("Black font");
private JButton changeToBlueButton = new JButton("Blue font");

public ChangeFontColorApplicationView(){
    super("Change font");
    JPanel buttonPanel = new JPanel();

    buttonPanel.add(changeToYellowButton);
    buttonPanel.add(changeToBlackButton);
    buttonPanel.add(changeToBlueButton);

    this.add(buttonPanel);
}

public void addButtonActionListener(){
    changeToYellowButton.addActionListener(new yellowBackgroundHandler());
    changeToBlackButton.addActionListener(new yellowBackgroundHandler());
    changeToBlueButton.addActionListener(new yellowBackgroundHandler());
}
}

控制者

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class ChangeFontColorApplicationController {
private ChangeFontColorApplicationView changeFontColorApplicationViewObject;
backgroundHandler yellowBackgroundHandlerObject = new yellowBackgroundHandler();
backgroundHandler blackBackgroundHandlerObject = new blackBackgroundHandler();
backgroundHandler blueBackgroundHandlerObject = new blueBackgroundHandler();

public ChangeFontColorApplicationController(ChangeFontColorApplicationView changeFontColorApplicationViewObject){
    this.changeFontColorApplicationViewObject = changeFontColorApplicationViewObject;

    yellowBackgroundHandlerObject.setNextHandlerInChain(blackBackgroundHandlerObject);
    blackBackgroundHandlerObject.setNextHandlerInChain(blueBackgroundHandlerObject);

    this.changeFontColorApplicationViewObject.addButtonActionListener();
}
}

现在，我创建了一个处理按钮事件的界面

public interface backgroundHandler extends ActionListener{
public void setNextHandlerInChain(backgroundHandler nextInChain);
public void handleCommand(String getActionCommandString);
public void actionPerformed(ActionEvent event);
}

每个实现接口的类都处理ActionEvent。如果不能，它将进入下一类（作为责任链）

黄色字体处理程序

import java.awt.Color;
import java.awt.event.ActionEvent;

public class yellowBackgroundHandler implements backgroundHandler{
private backgroundHandler nextInChain;
private ChangeFontColorApplicationView ChangeFontColorApplicationViewObject = new ChangeFontColorApplicationView();

public yellowBackgroundHandler(){}

@Override
public void setNextHandlerInChain(backgroundHandler nextInChain) {
    this.nextInChain = nextInChain;
}

@Override
public void handleCommand(String getActionCommandString) {
    if(getActionCommandString.equalsIgnoreCase("Yellow font")){
        ChangeFontColorApplicationViewObject.setBackground(Color.yellow);
    }
    else {
        nextInChain.handleCommand(getActionCommandString);
    }
}

@Override
public void actionPerformed(ActionEvent event) {
    try{
        handleCommand(event.getActionCommand());
    }
    catch (Exception exeption){
        ChangeFontColorApplicationViewObject.setTitle(exeption.toString());
    }
}
}

黑色字体处理程序

import java.awt.Color;
import java.awt.event.ActionEvent;

public class blackBackgroundHandler implements backgroundHandler{
private backgroundHandler nextInChain;
private ChangeFontColorApplicationView ChangeFontColorApplicationViewObject = new ChangeFontColorApplicationView();

public blackBackgroundHandler(){}

@Override
public void setNextHandlerInChain(backgroundHandler nextInChain) {
    this.nextInChain = nextInChain;
}

@Override
public void handleCommand(String getActionCommandString) {
    if(getActionCommandString.equalsIgnoreCase("Black font")){
        ChangeFontColorApplicationViewObject.setBackground(Color.BLACK);
    }
    else {
        nextInChain.handleCommand(getActionCommandString);
    }
}

@Override
public void actionPerformed(ActionEvent event) {
    try{
        handleCommand(event.getActionCommand());
    }
    catch (Exception exeption){
        ChangeFontColorApplicationViewObject.setTitle(exeption.toString());
    }
}
}

蓝色字体处理程序

import java.awt.Color;
import java.awt.event.ActionEvent;

public class blueBackgroundHandler implements backgroundHandler{
private backgroundHandler nextInChain;
private ChangeFontColorApplicationView ChangeFontColorApplicationViewObject = new ChangeFontColorApplicationView();

public blueBackgroundHandler(){}

@Override
public void setNextHandlerInChain(backgroundHandler nextInChain) {
    this.nextInChain = nextInChain;
}

@Override
public void handleCommand(String getActionCommandString) {
    if(getActionCommandString.equalsIgnoreCase("Μπλε φόντο")){
        ChangeFontColorApplicationViewObject.setBackground(Color.BLUE);
    }
    else {
        ChangeFontColorApplicationViewObject.setTitle("This is the back end of COR");
    }
}

@Override
public void actionPerformed(ActionEvent event) {
    try{
        handleCommand(event.getActionCommand());
    }
    catch (Exception exeption){
        ChangeFontColorApplicationViewObject.setTitle(exeption.toString());
    }
}
}

最后，我使用main方法创建类

public class ChangeFontColorApp {
public static void main(String[] args){
    ChangeFontColorApplicationView changeFontColorApplicationViewObject = new ChangeFontColorApplicationView();
    ChangeFontColorApplicationController changeFontColorApplicationControllerObject = new ChangeFontColorApplicationController(changeFontColorApplicationViewObject);

    changeFontColorApplicationViewObject.setVisible(true);
    changeFontColorApplicationViewObject.setSize(600, 600);
       changeFontColorApplicationViewObject.setDefaultCloseOperation(ChangeFontColorApplicationView.EXIT_ON_CLOSE);
}
}

有什么办法可以使这项工作吗？我不想有一个内部类用于事件处理，如果其中包含blick，则使用多个。任何建议将不胜感激。

最佳答案

那行不通。但是，问题不在于您有独立类（使用独立类就可以）。相反，问题是：

在视图类中，您具有：

public void addButtonActionListener(){
    changeToYellowButton.addActionListener(new yellowBackgroundHandler());
    changeToBlackButton.addActionListener(new yellowBackgroundHandler());
    changeToBlueButton.addActionListener(new yellowBackgroundHandler());
}

这意味着所有按钮的单击都由yellowBackgroundHandler处理。但是，yellowBackgroundHandler仅接受来自changeToYellowButton的点击。除此之外，还没有为YellowBackgroundHandler配置下一个处理程序。

要解决此问题，请在视图类中更改此内容：

public void addButtonActionListener(){
    changeToYellowButton.addActionListener(new yellowBackgroundHandler());
    changeToBlackButton.addActionListener(new yellowBackgroundHandler());
    changeToBlueButton.addActionListener(new yellowBackgroundHandler());
}

至

public void addButtonActionListener(backgroundHandler handler){
    changeToYellowButton.addActionListener(handler);
    changeToBlackButton.addActionListener(handler);
    changeToBlueButton.addActionListener(handler);
}

并在控制器类中更改以下内容：

this.changeFontColorApplicationViewObject.addButtonActionListener();

至

this.changeFontColorApplicationViewObject.addButtonActionListener(yellowBackgroundHandlerObject);

我看到的另一个问题是yellowBackgroundHandler，blackBackgroundHandler和blueBackgroundHandler具有私有变量ChangeFontColorApplicationViewObject，该变量指向其自己的ChangeFontColorApplicationView实例。我们需要此变量指向在main方法中创建的实例。为此，请更改此：

private ChangeFontColorApplicationView ChangeFontColorApplicationViewObject = new ChangeFontColorApplicationView();
public blueBackgroundHandler(){}

至：

private ChangeFontColorApplicationView ChangeFontColorApplicationViewObject;
public blueBackgroundHandler(ChangeFontColorApplicationView ChangeFontColorApplicationViewObject){
  this.ChangeFontColorApplicationViewObject = ChangeFontColorApplicationViewObject;
}

并更改此：

private ChangeFontColorApplicationView ChangeFontColorApplicationViewObject = new ChangeFontColorApplicationView();
public blackBackgroundHandler(){}

至：

private ChangeFontColorApplicationView ChangeFontColorApplicationViewObject;
public blackBackgroundHandler(ChangeFontColorApplicationView ChangeFontColorApplicationViewObject){
  this.ChangeFontColorApplicationViewObject = ChangeFontColorApplicationViewObject;
}

并更改此：

private ChangeFontColorApplicationView ChangeFontColorApplicationViewObject = new ChangeFontColorApplicationView();
public blueBackgroundHandler(){}

至：

private ChangeFontColorApplicationView ChangeFontColorApplicationViewObject;
public blueBackgroundHandler(ChangeFontColorApplicationView ChangeFontColorApplicationViewObject){
  this.ChangeFontColorApplicationViewObject = ChangeFontColorApplicationViewObject;
}

最后，更改此：

backgroundHandler yellowBackgroundHandlerObject = new yellowBackgroundHandler();
backgroundHandler blackBackgroundHandlerObject = new blackBackgroundHandler();
backgroundHandler blueBackgroundHandlerObject = new blueBackgroundHandler();

public ChangeFontColorApplicationController(ChangeFontColorApplicationView changeFontColorApplicationViewObject){
    this.changeFontColorApplicationViewObject = changeFontColorApplicationViewObject;

    yellowBackgroundHandlerObject.setNextHandlerInChain(blackBackgroundHandlerObject);
    blackBackgroundHandlerObject.setNextHandlerInChain(blueBackgroundHandlerObject);

    this.changeFontColorApplicationViewObject.addButtonActionListener();
}

至

backgroundHandler yellowBackgroundHandlerObject = new yellowBackgroundHandler();
backgroundHandler blackBackgroundHandlerObject = new blackBackgroundHandler();
backgroundHandler blueBackgroundHandlerObject = new blueBackgroundHandler();

public ChangeFontColorApplicationController(ChangeFontColorApplicationView changeFontColorApplicationViewObject){
    this.changeFontColorApplicationViewObject = changeFontColorApplicationViewObject;
    this.yellowBackgroundHandlerObject = new yellowBackgroundHandler(this.changeFontColorApplicationViewObject);
    this.blackBackgroundHandlerObject = new blackBackgroundHandler(this.changeFontColorApplicationViewObject);
    this.blueBackgroundHandlerObject = new blueBackgroundHandler(this.changeFontColorApplicationViewObject);

    yellowBackgroundHandlerObject.setNextHandlerInChain(blackBackgroundHandlerObject);
    blackBackgroundHandlerObject.setNextHandlerInChain(blueBackgroundHandlerObject);

    this.changeFontColorApplicationViewObject.addButtonActionListener(this.changeFontColorApplicationViewObject);
}