Design Pattern | Command Pattern (커맨드 패턴)

package com.devkuma.designpattern.behavioral.command.command;

public interface Command {
    void execute();
}

package com.devkuma.designpattern.behavioral.command.command;

import java.util.Iterator;
import java.util.Stack;

public class MacroCommand implements Command {

    // 명령 모음
    private Stack commands = new Stack();

    public void execute() {
        Iterator it = commands.iterator();
        while (it.hasNext()) {
            ((Command) it.next()).execute();
        }
    }

    // 추가
    public void append(Command cmd) {
        if (cmd != this) {
            commands.push(cmd);
        }
    }

    // 마지막 명령 삭제
    public void undo() {
        if (!commands.empty()) {
            commands.pop();
        }
    }

    // 전부 삭제
    public void clear() {
        commands.clear();
    }
}

package com.devkuma.designpattern.behavioral.command.drawer;

public interface Drawable {
    void draw(int x, int y);
}

package com.devkuma.designpattern.behavioral.command.drawer;

import com.devkuma.designpattern.behavioral.command.command.MacroCommand;

import java.awt.Canvas;
import java.awt.Color;
import java.awt.Graphics;

public class DrawCanvas extends Canvas implements Drawable {

    // 그리기 색상
    private Color color = Color.red;
    // 그리는 점의 반경
    private int radius = 6;
    // 이력
    private MacroCommand history;

    public DrawCanvas(int width, int height, MacroCommand history) {
        setSize(width, height);
        setBackground(Color.white);
        this.history = history;
    }

    // 전체 이력 다시 그리기
    public void paint(Graphics g) {
        history.execute();
    }

    // 그리기
    public void draw(int x, int y) {
        Graphics g = getGraphics();
        g.setColor(color);
        g.fillOval(x - radius, y - radius, radius * 2, radius * 2);
    }
}

package com.devkuma.designpattern.behavioral.command.drawer;

import com.devkuma.designpattern.behavioral.command.command.Command;

import java.awt.Point;

public class DrawCommand implements Command {

    // 그리기 대상
    protected Drawable drawable;
    // 그리기 위치
    private Point position;

    public DrawCommand(Drawable drawable, Point position) {
        this.drawable = drawable;
        this.position = position;
    }

    public void execute() {
        drawable.draw(position.x, position.y);
    }
}

package com.devkuma.designpattern.behavioral.command;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;
import java.awt.event.WindowEvent;
import java.awt.event.WindowListener;

import javax.swing.Box;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFrame;

import com.devkuma.designpattern.behavioral.command.command.Command;
import com.devkuma.designpattern.behavioral.command.command.MacroCommand;
import com.devkuma.designpattern.behavioral.command.drawer.DrawCanvas;
import com.devkuma.designpattern.behavioral.command.drawer.DrawCommand;


public class Main extends JFrame implements ActionListener, MouseMotionListener, WindowListener {

    // 그리기 이력
    private MacroCommand history = new MacroCommand();
    // 그리기 영역
    private DrawCanvas canvas = new DrawCanvas(400, 400, history);
    // 실행 취소 버튼
    private JButton undoButton = new JButton("undo");
    // 지우기 버튼
    private JButton clearButton = new JButton("clear");

    public Main(String title) {
        super(title);

        this.addWindowListener(this);
        canvas.addMouseMotionListener(this);
        undoButton.addActionListener(this);
        clearButton.addActionListener(this);

        Box buttonBox = new Box(BoxLayout.X_AXIS);
        buttonBox.add(undoButton);
        buttonBox.add(clearButton);
        Box mainBox = new Box(BoxLayout.Y_AXIS);
        mainBox.add(buttonBox);
        mainBox.add(canvas);
        getContentPane().add(mainBox);

        pack();
        setVisible(true);
    }

    // ActionListener 용
    public void actionPerformed(ActionEvent e) {
        Object source = e.getSource();
        if (source == undoButton) {
            history.undo();
            canvas.repaint();
        } else if (source == clearButton) {
            history.clear();
            canvas.repaint();
        }
    }

    // MouseMotionListener用
    public void mouseMoved(MouseEvent e) {
    }

    public void mouseDragged(MouseEvent e) {
        Command cmd = new DrawCommand(canvas, e.getPoint());
        history.append(cmd);
        cmd.execute();
    }

    // WindowListener 용
    public void windowClosing(WindowEvent e) {
    }

    public void windowActivated(WindowEvent e) {
    }

    public void windowClosed(WindowEvent e) {
    }

    public void windowDeactivated(WindowEvent e) {
    }

    public void windowDeiconified(WindowEvent e) {
    }

    public void windowIconified(WindowEvent e) {
    }

    public void windowOpened(WindowEvent e) {
    }

    public static void main(String[] args) {
        new Main("Command Pattern Sample");
    }
}