设计模式—命令模式

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

代码

接受者，命令执行

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public abstract class  Receiver {
    public abstract void doSomething();
}
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public class ConcreteReceiver1 extends Receiver {
    @Override
    public void doSomething() {
        System.out.println("receiver1");
    }
}
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public class ConcreteReceiver2 extends  Receiver {
    @Override
    public void doSomething() {
        System.out.println("receiver2");
    }
}

命令者

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public abstract class Command {
    public abstract void execute();
}
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public class ConcreteCommand1 extends Command {

    private Receiver receiver;

    public ConcreteCommand1(Receiver receiver) {
        this.receiver = receiver;
    }

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

    private Receiver receiver;

    public ConcreteCommand2(Receiver receiver) {
        this.receiver = receiver;
    }

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

调用者

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public class Invoke {
    private Command command;

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

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

}

测试:

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public class InvokeTest {

    @Test
    public void testInvoke(){
        Invoke invoke = new Invoke();
        Receiver receiver = new ConcreteReceiver1();
        Command command = new ConcreteCommand1(receiver);
        invoke.setCommand(command);
        invoke.action();
    }

}