Java中命令的用法_Java中命令模式的使用

// 1. 定义命令接口
interface Command {
    void execute();
    void undo(); // 可选：用于支持撤销
}

// 2. 定义具体的命令类
class ConcreteCommand implements Command {
    private Receiver receiver; // 命令的接收者
    private String action; // 命令的具体操作

    public ConcreteCommand(Receiver receiver, String action) {
        this.receiver = receiver;
        this.action = action;
    }

    @Override
    public void execute() {
        receiver.action(action);
    }

    @Override
    public void undo() {
        receiver.undoAction(action); // 可选：用于支持撤销
    }
}

// 3. 定义接收者类
class Receiver {
    public void action(String action) {
        System.out.println("Receiver executing action: " + action);
    }

    public void undoAction(String action) {
        System.out.println("Receiver undoing action: " + action);
    }
}

// 4. 定义调用者类
class Invoker {
    private Command command;

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

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

    public void undoCommand() {
        command.undo(); // 可选：用于支持撤销
    }
}

// 5. 客户端代码
public class Client {
    public static void main(String[] args) {
        Receiver receiver = new Receiver();
        ConcreteCommand command1 = new ConcreteCommand(receiver, "open");
        ConcreteCommand command2 = new ConcreteCommand(receiver, "close");

        Invoker invoker = new Invoker();
        invoker.setCommand(command1);
        invoker.executeCommand(); // 输出：Receiver executing action: open

        invoker.setCommand(command2);
        invoker.executeCommand(); // 输出：Receiver executing action: close

        invoker.undoCommand(); // 输出：Receiver undoing action: close  (如果实现了undo方法)
    }
}