命令模式举例-模拟小电器

我们用命令模式模拟一个带控制开关的小电器。该小电器上有四个开关，两个一组，其中一组负责打开、关闭照明灯，另一组负责打开、关闭小电器上的摄像头。

设计要求

1. 设计Cammera类（模拟摄像头）和Light类（模拟照明灯）。
2. 设计Machine类（模拟小电器）。
3. 要求Machine类创建的对象中含有打开、关闭摄像头以及打开、关闭照明灯的按钮。

设计实现

设计类图如图：

1.接收者

Cammera类和Light类的实例是命令模式的接收者。

//Cammera.java
import javax.swing.*;
public class Cammera extends JPanel {
	String name;
	Icon imageIcon;
	JLabel label;
	public Cammera() {
		label = new JLabel("I am Cammera");
		add(label);
	}
	public void on() {
		label.setText("Cammera open");
	}
	public void off() {
		label.setText("Cammera off");
	}
}

//Light.java
import javax.swing.*;
public class Light extends JPanel{
	String name;
	JLabel label;
	public Light() {
		label = new JLabel("I am Light");
		add(label);
	}
	public void on() {
		label.setText("Light open");
	}
	public void off() {
		label.setText("Light off");
	}
}

命令接口

public interface Command {
	public abstract void execute();
	public abstract String getName();
}

具体命令

// OnCammeraCommand.java
public class OnCammeraCommand implements Command {
	Cammera cammera;
	public OnCammeraCommand(Cammera cammera){
		this.cammera = cammera;
	}
	public void execute() {
		cammera.on();
	}
	public String getName() {
		return "打开摄像头";
	}
}

// OffCammeraCommand.java
public class OffCammeraCommand implements Command {
	Cammera cammera;
	public OffCammeraCommand(Cammera cammera) {
		this.cammera = cammera;
	}
	public void execute() {
		cammera.off();
	}
	public String getName() {
		return "关闭摄像头";
	}
}

// OnLightCommand.java
public class OnLightCommand implements Command {
	Light light;
	public OnLightCommand(Light light){
		this.light = light;
	}
	public void execute() {
		light.on();
	}
	public String getName() {
		return "打开照明灯";
	}
}

// OffLightCommand.java
public class OffLightCommand implements Command {
	Light light;
	public OffLightCommand(Light light) {
		this.light = light;
	}
	public void execute() {
		light.off();
	}
	public String getName() {
		return "关闭照明灯";
	}
}

请求者

Invoke类的实例含有程序所需要的按钮。

import java.awt.*;
import javax.swing.*;
public class Invoke {
	JButton button;
	Command command;
	public Invoke() {
		button = new JButton();
		button.addActionListener(new ActionListener() {
			@Override
			public void actionPerformed(ActionEvent e) {
				executeCommand();
			}

		});
	}
	private void executeCommand() {
		System.out.println(command.getName());
		command.execute();
	}
	public void setCommand(Command command) {
		this.command = command;
		button.setText(command.getName());
	}
	public JButton getButton() {
		return button;
	}

}

小电器

import java.awt.*;
import javax.swing.*;
public class Machine extends JFrame {
	Invoke requestOnCammera,requestOffCammera,requestOnLight,requestOffLight;
	Cammera cammera;
	Light light;
	public Machine() {
		setTitle("小电器");
		requestOnCammera = new Invoke();
		requestOffCammera = new Invoke();
		cammera = new Cammera();
		light = new Light();
		requestOnCammera.setCommand(new OnCammeraCommand(cammera));
		requestOffCammera.setCommand(new OffCammeraCommand(cammera));
		requestOnLight = new Invoke();
		requestOffLight = new Invoke();
		requestOnLight.setCommand(new OnLightCommand(light));
		requestOffLight.setCommand(new OffLightCommand(light));
		initPosition();
		setSize(500,300);
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		setVisible(true);
	}
	private void initPosition() {
		JPanel ps = new JPanel();
		ps.add(requestOnCammera.getButton());
		ps.add(requestOffCammera.getButton());
		ps.add(requestOnLight.getButton());
		ps.add(requestOffLight.getButton());
		add(ps, BorderLayout.SOUTH);
		add(light, BorderLayout.WEST);
		add(cammera, BorderLayout.EAST);
	}
	public static void main(String[] args) {
		Machine machine = new Machine();
	}
}