图解Java设计模式之访问者模式

package com.example.demo.visitor;

import javax.activation.MailcapCommandMap;

public abstract class Action {
	
	/**
	 * 得到男性的测评
	 * @param man
	 */
	public abstract void getManResult(Man man);
	
	/**
	 * 得到女的测评
	 * @param woman
	 */
	public abstract void getWomanResult(Woman woman);

}
package com.example.demo.visitor;

public class Fail extends Action{

	@Override
	public void getManResult(Man man) {
		// TODO Auto-generated method stub
		System.out.println(" 男人给的评价该歌手很失败 ！ ");
	}

	@Override
	public void getWomanResult(Woman woman) {
		// TODO Auto-generated method stub
		System.out.println(" 女人给的评价该歌手很失败 ！ ");
	}

}
package com.example.demo.visitor;

public class Success extends Action{

	@Override
	public void getManResult(Man man) {
		// TODO Auto-generated method stub
		System.out.println(" 男人给的评价该歌手很成功 ！ ");
	}

	@Override
	public void getWomanResult(Woman woman) {
		// TODO Auto-generated method stub
		System.out.println(" 女人给的评价该歌手很成功 ！ ");
	}

}
package com.example.demo.visitor;

public abstract class Person {
	
	public abstract void accept(Action action);
}
package com.example.demo.visitor;

public class Man extends Person {

	@Override
	public void accept(Action action) {
		// TODO Auto-generated method stub
		action.getManResult(this);
	}

}
package com.example.demo.visitor;

/**
 * 说明
 * 1. 这里我们使用到了双分派，即首先在客户端程序中，将具体状态作为参数传递Woman中（第一次分派）
 * 2. 然后Woman 类调用作为参数的 “具体方法” 中方法getWomanResult，同时将自己（this）作为参数传入，完成第二次的分派
 * @author zhaozhaohai
 *
 */
public class Woman extends Person {

	@Override
	public void accept(Action action) {
		// TODO Auto-generated method stub
		action.getWomanResult(this);
	}

}
package com.example.demo.visitor;

import java.util.LinkedList;
import java.util.List;

/**
 * 数据结构，管理很多人（Man，Woman）
 * @author zhaozhaohai
 *
 */
public class ObjectStructure {

	/**
	 * 维护一个集合
	 */
	private List<Person> persons = new LinkedList<Person>();
	
	/**
	 * 增加到list
	 * @param person
	 */
	public void attach(Person person) {
		persons.add(person);
	}
	
	/**
	 * 移除
	 * @param person
	 */
	public void detach(Person person) {
		persons.remove(person);
	}
	
	/**
	 * 显示测试情况
	 * @param action
	 */
	public void display(Action action) {
		for (Person person : persons) {
			person.accept(action);
		}
	}
}
package com.example.demo.visitor;

public class Wait extends Action{

	@Override
	public void getManResult(Man man) {
		// TODO Auto-generated method stub
		System.out.println(" 男人给的评价是该歌手待定。。 ");
	}

	@Override
	public void getWomanResult(Woman woman) {
		// TODO Auto-generated method stub
		System.out.println(" 女人给的评价是该歌手待定。。 ");
	}

}
package com.example.demo.visitor;

public class Client {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		// 创建ObjectStructure
		ObjectStructure objectStructure = new ObjectStructure();
		objectStructure.attach(new Man());
		objectStructure.attach(new Woman());
		
		// 成功
		Success success = new Success();
		objectStructure.display(success);
		System.out.println("-------------------");
		// 失败
		Fail fail = new Fail();
		objectStructure.display(fail);
		System.out.println("----------给的是待定的测评------------");
		Wait wait = new Wait();
		objectStructure.display(wait);
	}

}