java内的命令(Command)模式例子

命令模式例子------创世纪系统

 

系统开始时，世界是个黑暗的窗体，窗体上有4个按钮： Let There Be Light(要有光), Let There Be Land(要有地),Reset(复原),God Rests(上帝休息了)

 

代码:

/* 抽象命令角色 */ public interface CommandFromGod { public void Execute(); }

 

import java.awt.*; import java.awt.event.*; /* 具体命令角色，Let There be light*/ public class LetThereBeLightCommand extends Button implements CommandFromGod { Panel p; public LetThereBeLightCommand(String caption, Panel pnl) { super(caption); p = pnl; } public void Execute() { p.setBackground(Color.white); } }

 

import java.awt.*; import java.awt.event.*; /* 具体命令角色，Let There be land*/ public class LetThereBeLandCommand extends Button implements CommandFromGod { Panel p; public LetThereBeLandCommand(String caption, Panel pnl) { super(caption); p = pnl; } public void Execute() { p.setBackground(Color.orange); } }

 

import java.awt.*; import java.awt.event.*; /* 具体命令角色，Rests*/ public class GodRestsCommand extends Button implements CommandFromGod { public GodRestsCommand(String caption) { super(caption); } public void Execute() { System.exit(0); } }

 

import java.awt.*; import java.awt.event.*; /* 具体命令角色，Reset*/ public class ResetCommand extends Button implements CommandFromGod { Panel p; public ResetCommand(String caption, Panel pnl) { super(caption); p = pnl; } public void Execute() { p.setBackground(Color.black); } }

 

import java.awt.*; import java.awt.event.*; /* Client */ public class TheWorld extends Frame implements ActionListener { LetThereBeLightCommand btnLight; LetThereBeLandCommand btnLand; ResetCommand btnReset; GodRestsCommand btnExit; Panel p; public TheWorld() { super("This is the world, and God says..."); p = new Panel(); p.setBackground(Color.black); add(p); btnLight = new LetThereBeLightCommand("Let there be light", p); btnLand = new LetThereBeLandCommand("Let there be land", p); btnReset = new ResetCommand("Reset", p); btnExit = new GodRestsCommand("God rests"); p.add(btnLight); p.add(btnLand); p.add(btnReset); p.add(btnExit); btnLight.addActionListener(this); btnLand.addActionListener(this); btnReset.addActionListener(this); btnExit.addActionListener(this); setBounds(100,100,400,200); setVisible(true); } //----------------------------------------- public void actionPerformed(ActionEvent e) { CommandFromGod obj = (CommandFromGod)e.getSource(); obj.Execute(); } //----------------------------------------- static public void main(String[] argv) { new TheWorld(); } }

 这个例子中没有Recevier角色和Invoker角色，此处完全可以分离出这两种角色，这样的话似乎更复杂了！

相关资源：敏捷开发V1.0.pptx