1.定义#

将一个请求封装成一个对象，从而让你使用不同的请求把客户端参数化，对请求排队或者记录请求日志，可以提供命令的撤销和恢复功能。将请求与与请求处理者解耦合。命令模式主要有三个部分接收命令的部分Invoke，具体的命令对象ConcreteCommand，命令的处理者Receiver。

2.类图#

类图

3.实现#

3.1抽象接收者类##

public interface Receiver {
    public void doSomething();
}

3.2具体接收者类##

public class ConcreteReceiver1 implements Receiver{
    @Override
    public void doSomething() {
        System.out.println("执行操作1");
    }
}

public class ConcreteReceiver2 implements Receiver{
    @Override
    public void doSomething() {
        System.out.println("执行操作2”);
    }
}

3.3抽象命令类##

public abstract class Command {
    protected ConcreteReceiver1 concreteReceiver1 = new ConcreteReceiver1();
    protected ConcreteReceiver2 concreteReceiver2 = new ConcreteReceiver2();

    public abstract void execute();
}

3.4具体命令类##

public class ConcreteCommand1 extends Command {
    @Override
    public void execute() {
        super.concreteReceiver1.doSomething();
    }
}

public class ConcreteCommand2 extends Command {
    @Override
    public void execute() {
        super.concreteReceiver2.doSomething();
    }
}

3.5中间者类##

public class Invoke {
    private Command command = null;

    public Invoke() {

    }

    public Invoke(Command _command) {
        this.command = _command;
    }

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

    public void action() {
        this.command.execute();
    }
}

3.6客户端类##

public class Client {
    public static void main(String args[]) {
        Command command1 = new ConcreteCommand1();
        Invoke invoke = new Invoke(command1);
        invoke.action();

        Command command2 = new ConcreteCommand2();
        invoke.setCommand(command2);
        invoke.action();

    }
}