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我对使用 Java Graphics2D 在 MVC 上的尝试提出意见。我想通过一个简单的例子来了解 MVC。

请问我做对了吗？

文档在这里。

http://en.wikipedia.org/wiki/Model%E2%80%93view%E2%80%93controller

http://www.oracle.com/technetwork/articles/javase/index-142890.html

反馈赞赏欢呼。

编辑：下面的代码现已根据 Rasmus 的反馈和进一步的研究得到修复。

public class App {

    /*
     * The view registers as a listener on the model. Any changes to the
     * underlying data of the model immediately result in a broadcast change
     * notification, which the view receives.
     * 
     * Note that the model is not aware of the view or the controller -- it
     * simply broadcasts change notifications to all interested listeners.
     * 
     * The controller is bound to the view. This typically means that any user
     * actions that are performed on the view will invoke a registered listener
     * method in the controller class.
     * 
     * The controller is given a reference to the underlying model.
     */
    public static void main(String[] args) {
        Model model = new Model();
        Controller controller = new Controller(model);
        View view = new View(controller);
        model.addModelChangedListener(view);

    }
}

import java.awt.Rectangle;
import java.util.ArrayList;
import java.util.Iterator;

public class Model {

    private ArrayList<Rectangle> rectangles = new ArrayList<Rectangle>();
    private ArrayList<ModelChangedEventListener> listeners = new ArrayList<ModelChangedEventListener>();

    public void addRectangle(int x, int y, int width, int height) {
        rectangles.add(new Rectangle(x, y, width, height));
        modelChangedEvent();
    }

    public ArrayList<Rectangle> getRectangles() {
        return rectangles;
    }

    public synchronized void addModelChangedListener(
            ModelChangedEventListener listener) {
        listeners.add(listener);
    }

    public synchronized void removeModelChangedListener(
            ModelChangedEventListener listener) {
        listeners.remove(listener);
    }

    private synchronized void modelChangedEvent() {
        ModelChangeEvent event = new ModelChangeEvent(this);
        Iterator<ModelChangedEventListener> i = listeners.iterator();
        while (i.hasNext()) {
            ((ModelChangedEventListener) i.next()).handleModelChange(event);
        }
    }

}

import java.awt.Container;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.util.EventObject;

import javax.swing.JFrame;
import javax.swing.JPanel;

public class View extends JFrame implements ModelChangedEventListener {

    private static final int DISPLAY_WIDTH = 300;
    private static final int DISPLAY_HEIGHT = 300;
    private ViewPanel viewPanel;
    private Controller controller;

    public View(Controller controller) {
        this.controller = controller;
        setSize(DISPLAY_WIDTH, DISPLAY_HEIGHT);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        Container contentPane = getContentPane();
        viewPanel = new ViewPanel();
        contentPane.add(viewPanel);
        setVisible(true);
    }

    @Override
    public void handleModelChange(EventObject e) {
        viewPanel.repaint();
    }

    public class ViewPanel extends JPanel implements MouseListener {

        public ViewPanel() {
            addMouseListener(this);
        }

        public void paintComponent(Graphics g) {
            Graphics2D g2 = (Graphics2D) g;
            controller.draw(g2);
        }

        @Override
        public void mouseClicked(MouseEvent arg0) {
            controller.click(arg0.getX(), arg0.getY());
        }

        @Override
        public void mouseEntered(MouseEvent arg0) {
        }

        @Override
        public void mouseExited(MouseEvent arg0) {
        }

        @Override
        public void mousePressed(MouseEvent arg0) {
        }

        @Override
        public void mouseReleased(MouseEvent arg0) {
        }

    }

}

import java.awt.Graphics2D;
import java.awt.Rectangle;

public class Controller {

    private Model model;

    public Controller(Model model) {
        this.model = model;
    }

    public void click(int x, int y) {
        model.addRectangle(x, y, 25, 25);
    }

    public void draw(Graphics2D g2) {
        for (Rectangle rectangle : model.getRectangles()) {
            g2.draw(rectangle);
        }
    }
}

import java.util.EventObject;

public interface ModelChangedEventListener {
    public void handleModelChange(EventObject e);
}

public class ModelChangeEvent extends java.util.EventObject {

    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    public ModelChangeEvent(Object source) {
        super(source);
    }
}
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1 回答 1

3

你弄错了。MVC的要点之一就是让模型独立于视图。即模型不应该知道视图（或者更确切地说它不应该需要关心）。另一方面，视图需要使用模型对象来做它的事情。我从来没有设计过考虑 MVC 的非 Web 应用程序。视图通常是一个 JSP/HTML/XHTML/XML 文件，它的作用是使程序以某种方式显示。所以关于渲染、放置等的一切都适合视图。控制器的工作是从模型中收集数据并将其以视图可以以简单方式使用的形式传递给视图，并处理视图之间的导航等事情。它是将视图和模型保持在一起的粘合剂。因此：

模型不依赖任何东西。控制器取决于型号。视图取决于控制器和模型。

于 2012-09-17T07:09:16.240 回答