java 命令模式（大话设计模式）

命令模式：将一个请求封装为一个对象，从而使你可用不同的请求对客户进行参数化；对请求排队或记录请求日志，以及支持可撤销的操作。命令模式把请求一个操作的对象与知道怎么执行一个操作的对象分割开。【组合】

/**
 * 用来声明执行操作的接口
 * 
 * @author administrator
 *
 */
public abstract class Command {

    protected List<Reciever> recievers;

    public Command(List<Reciever> recievers) {
	this.recievers = recievers;
    }

    public void addRecievers(Reciever reciever) {
	this.recievers.add(reciever);
    }

    public abstract void execute();

}

// 将一个接收者对象绑定于一个动作，调用接收者相应的操作，以实现execute
class ConcreteCommand extends Command {

    public ConcreteCommand(List<Reciever> recievers) {
	super(recievers);
    }

    @Override
    public void execute() {
	for (Reciever reciever : recievers) {
	    reciever.action();
	}
    }

}
/**
 * 知道如何实施与执行一个与请求相关的操作，任何类都可能作为一个接收者。真正执行请求的地方！
 * 
 * @author administrator
 *
 */
interface Reciever {
    public void action();
}

class RecieverA implements Reciever {

    @Override
    public void action() {
	System.out.println("RecieverA执行请求！");
    }

}

class RecieverB implements Reciever {

    @Override
    public void action() {
	System.out.println("RecieverB执行请求！");
    }
}

class RecieverC implements Reciever {

    @Override
    public void action() {
	System.out.println("RecieverC执行请求！");
    }
}
/**
 * 要求该命令执行这个请求
 * 
 * @author administrator
 *
 */
public class Invoker {

    private Command command;

    public void setCommand(Command command) {
	this.command = command;
    }

    public void executeCommand() {
	command.execute();
    }

}
/**
 * 创建一个具体命令对象并设定它的接收者
 * 
 * @author administrator
 *
 */
public class CommandClient {

    public static void main(String[] args) {
	List<Reciever> recievers = new ArrayList<Reciever>();

	recievers.add(new RecieverA());
	recievers.add(new RecieverB());
	recievers.add(new RecieverC());

	Command command = new ConcreteCommand(recievers);
	Invoker invoker = new Invoker();

	invoker.setCommand(command);
	invoker.executeCommand();

    }

}

案例 烤羊肉串

/**
 * 命令模式(Command)
 * 抽象命令类
 */
public abstract class Command {

    protected BarbecueMan receiver;

    public Command(BarbecueMan receiver) {
        this.receiver = receiver;
    }

    // 执行命令
    public abstract void excuteCommand();

}
/**
 * 命令模式(Command)
 * 具体烤鸡翅命令
 */
public class BakeChickenWingCommand extends Command {

    public BakeChickenWingCommand(BarbecueMan receiver) {
        super(receiver);
    }

    @Override
    public void excuteCommand() {
        receiver.bakeChickenWing();
    }

    @Override
    public String toString() {
        return "烤鸡翅";
    }
}
/**
 * 命令模式(Command)
 * 具体烤羊肉命令
 */
public class BakeMuttonCommand extends Command {

    public BakeMuttonCommand(BarbecueMan receiver) {
        super(receiver);
    }

    @Override
    public void excuteCommand() {
        receiver.bakeMutton();
    }

    @Override
    public String toString() {
        return "烤羊肉";
    }

}
/**
 * 命令模式(Command)
 * 烤肉串者
 */
public class BarbecueMan {

    // 烤羊肉
    public void bakeMutton() {
        System.out.println("烤羊肉");
    }

    // 烤鸡翅
    public void bakeChickenWing() {
        System.out.println("烤鸡翅");
    }

}
/**
 * 命令模式(Command)
 * 服务员
 */
public class Waiter {

    private List<Command> orders = new ArrayList<>();

    // 设置订单
    public void setOrder(Command command) {
        if (command.toString() == "烤鸡翅") {
            System.out.println("服务员：鸡翅没有了，请点别的烧烤。");
        } else {
            orders.add(command);
            System.out.println("增加订单：" + command.toString() + " 时间：" + new Date().toString());
        }
    }

    // 取消订单
    public void cancelOrder(Command command) {
        orders.remove(command);
        System.out.println("取消订单：" + command.toString() + " 时间：" + new Date().toString());
    }

    // 通知全部执行
    public void notice() {
        for (Command cmd : orders) {
            cmd.excuteCommand();
        }
    }

}
/**
 * 命令模式(Command)
 * 客户端main方法
 */
public class Client {

    public static void main(String[] args) {
        // 开店前的准备
        BarbecueMan man = new BarbecueMan();
        Command bakeMuttonCommand1 = new BakeMuttonCommand(man);
        Command bakeMuttonCommand2 = new BakeMuttonCommand(man);
        Command bakeChickenWingCommand = new BakeChickenWingCommand(man);
        Waiter waiter = new Waiter();
        // 开门营业
        waiter.setOrder(bakeMuttonCommand1);
        waiter.setOrder(bakeMuttonCommand2);
        waiter.setOrder(bakeChickenWingCommand);
        // 点菜完毕，通知厨房
        waiter.notice();
    }

}