享元模式

享元模式（Flyweight Pattern）：将很多相同或非常相似的对象封装成同一个对象（享元对象），将它们的相同之处作为享元对象的属性，不同之处作为参数传入。使用享元模式可以减少系统对象的个数，提高对象的复用率。例如在自动装箱时，一个字节大小以内的整数都被封装成同一个对象。例如在购买书时，可以将同一作者的所有书封装在一起，作为另一个对象放进集合里。

实体类：Book

 

package com.domain;

public class Book {
	private String author;

	public Book(String author) {
		super();
		this.author = author;
	}

	public String getAuthor() {
		return author;
	}

	public void setAuthor(String author) {
		this.author = author;
	}
	
}

实体类：Persion

 

 

package com.domain;

public class Persion {
	private String name;
	
	public Persion(String name) {
		super();
		this.name = name;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public void BuyBook(Book book){
		System.out.println(name+"购买了一本"+book.getAuthor()+"的书");
	};
}

享元工厂类：FlyweightFactory

package com.factory;

import java.util.HashMap;
import java.util.Map;

import com.domain.Book;

public class FlyweightFactory {
	static Map<String, Book> books=new HashMap<String, Book>();
	public static Book getFlyweightInstance(String author){
		Book book=books.get(author);
		if (book==null) {
			book=new Book(author);
			books.put(author, book);
		}
		return book;
	}
	public static int getInstance(){
		return books.size();
	}
}

测试类：Test

 

 

package com.test;

import com.domain.Book;
import com.domain.Persion;
import com.factory.FlyweightFactory;

public class Test {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Persion persion=new Persion("小明");
		Book book=FlyweightFactory.getFlyweightInstance("鲁迅");
		persion.BuyBook(book);
		Book book2=FlyweightFactory.getFlyweightInstance("冰心");
		persion.BuyBook(book2);
		Book book3=FlyweightFactory.getFlyweightInstance("茅盾");
		persion.BuyBook(book3);
		Book book4=FlyweightFactory.getFlyweightInstance("鲁迅");
		persion.BuyBook(book4);
		Book book5=FlyweightFactory.getFlyweightInstance("冰心");
		persion.BuyBook(book5);
		System.out.println(persion.getName()+"一共买了"+FlyweightFactory.getInstance()+"个作者的书");
	}

}

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