命令模式（1）

命令模式的四种角色：

1、接受者（Receiver）负责执行请求的相关操作的一个类

2、命令接口：（Command）用于封装请求的方法

3、具体命令：（ConcreteCommand）命令接口的具体实现类

4、请求者：（Invoker）包含了命令接口的实例变量，负责调用具体命令

请求者：
package DesignPatterns.CommandMode;

public class Invoker {
    private Command command;

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

命令接口：
package DesignPatterns.CommandMode;

public interface Command {
    public void execute();
}

具体命令：

package DesignPatterns.CommandMode;

public class ConcreteCommand implements Command{
    private Receiver receiver;
    public ConcreteCommand(Receiver receiver)
    {
        this.receiver=receiver;
    }
    public void execute()
    {
        receiver.printCommand();
    }


}

接受者：

package DesignPatterns.CommandMode;

public class Receiver {
    public void printCommand()
    {
        System.out.println("执行命令");
    }

}

测试类：

package DesignPatterns.CommandMode;

public class Application {
    public static void main(String[] args)
    {
        Receiver receiver=new Receiver();
        Command command=new ConcreteCommand(receiver);
        Invoker invoker=new Invoker();
        invoker.setCommand(command);
        invoker.startCommand();

    }
}