作者网页：www.jcohy.com
我的学习笔记，记录学习过程中的笔记以及遇到的问题,以及我的一些经验总结。如果出现链接失效,或者想知道更多的内容等情况可以提交 Issues 提醒我修改相关内容。
命令模式：将一个请求封装成一个对象，从而使你可用不同的请求对客户进行参数化，对请求排队或者记录请求日志，以及支持可撤销的操作。
- Command
用来声明 执行操作的接口
- ConcreteCommand
将一个接受者对象绑定于一个动作，调用接受者相应的操作，以实现Excute。
- Receiver
知道如何实施与执行一个请求相关的操作，任何类都可能作为一个接受者。
- Invoker
要求该命令执行这个请求
- Client
简单的绘图软件，移动鼠标时自动绘制一个红点，按下clear 清除所有
1.表示命令的接口。
public interface Command {
public abstract void execute();
}
2.
public class MacroCommand implements Command{
private Stack<Command> commands = new Stack<>();
@Override
public void execute() {
Iterator<Command> it = commands.iterator();
while(it.hasNext()) {
((Command)it.next()).execute();
}
}
public void append(Command cmd) {
if(cmd!=this) {
commands.push(cmd);
}
}
//删除最后一个命令
public void undo() {
if(!commands.empty())
commands.pop();
}
public void clear() {
commands.clear();
}
}
3.
public class DrawCommand implements Command{
private Drawable drawable;
private Point point;
public DrawCommand(Drawable drawable,Point point) {
this.drawable = drawable;
this.point = point;
}
@Override
public void execute() {
drawable.draw(point.x, point.y);
}
}
4.
public interface Drawable {
public abstract void draw(int x,int y);
}
5.
public class DrawCanvas extends Canvas implements Drawable {
private static final long serialVersionUID = 1L;
private Color color = Color.red;//颜色
private int radius = 6;//点的半径
private MacroCommand history ;//记录
public DrawCanvas(int width,int height,MacroCommand history) {
setSize(width,height);
setBackground(Color.WHITE);
this.history = history;
}
//再度绘制整个记录
public void paint(Graphics g) {
history.execute();
}
//绘制
@Override
public void draw(int x, int y) {
Graphics g = getGraphics();
g.setColor(color);
g.fillOval(x-radius, y-radius, radius*2, radius*2);
}
}
6.
public class Client extends JFrame implements ActionListener,MouseMotionListener,WindowListener{
private MacroCommand history = new MacroCommand();//绘制记录
private DrawCanvas drawCanvas = new DrawCanvas(400, 400, history);//绘制区域
private JButton cleanButton = new JButton("clear");//删除键
public Client(String title) {
super(title);
this.addWindowListener(this);
drawCanvas.addMouseMotionListener(this);
cleanButton.addActionListener(this);
Box buttonBox = new Box(BoxLayout.X_AXIS);
buttonBox.add(cleanButton);
Box mainBox = new Box(BoxLayout.Y_AXIS);
mainBox.add(buttonBox);
mainBox.add(drawCanvas);
getContentPane().add(mainBox);
pack();
setVisible(true);
}
@Override
public void windowActivated(WindowEvent e) {
// TODO Auto-generated method stub
}
@Override
public void windowClosed(WindowEvent e) {
// TODO Auto-generated method stub
}
@Override
public void windowClosing(WindowEvent e) {
System.exit(0);
}
@Override
public void windowDeactivated(WindowEvent e) {
// TODO Auto-generated method stub
}
@Override
public void windowDeiconified(WindowEvent e) {
// TODO Auto-generated method stub
}
@Override
public void windowIconified(WindowEvent e) {
// TODO Auto-generated method stub
}
@Override
public void windowOpened(WindowEvent e) {
// TODO Auto-generated method stub
}
@Override
public void mouseDragged(MouseEvent e) {
Command cmd = new DrawCommand(drawCanvas,e.getPoint());
history.append(cmd);
cmd.execute();
}
@Override
public void mouseMoved(MouseEvent e) {
}
@Override
public void actionPerformed(ActionEvent e) {
if(e.getSource() == cleanButton) {
history.clear();
drawCanvas.repaint();
}
}
public static void main(String[] args) {
new Client("Command Pattern Sample");
}
}
7.result
- java.lang.Runnable
- javax.swing.Action