Commit d64c9da

author

deeper

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add flyweight

1 parent fb7b25a commit d64c9daCopy full SHA for d64c9da

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	`1`	`+package com.ruoxu.pattern.flyweight;`
	`2`	`+/**`
	`3`	`+ * 享元模式(是对象池的一种实现,flyweight轻量级)`
	`4`	`+ * 享元模式尽可能减少内存使用量`
	`5`	`+ *`
	`6`	`+ * 定义:使用共享对象可有效地支持大量的细粒度的对象。`
	`7`	`+ *`
	`8`	`+ * 使用场景:`
	`9`	`+ * 1.系统中存在大量相似对象`
	`10`	`+ * 2.细粒度的对象都具备较接近的外部状态,而且内部状态与环境无关,也就是说对象没有特定身份。享元模式通过消息吃的形式有效地减少了重复对象的存在。它通过内部状态标示某个种类的对象,外部程序根据这个不会变化的内部状态从消息池中取出对象,使得同一类对象可以被复用,避免大量重复对象。(这句话结合例子即可理解)`
	`11`	`+ * 3.需要缓冲池的场景`
	`12`	`+ */`
	`13`	`+public class Demo {`
	`14`	`+ public static void main(String[] args) {`
	`15`	`+ Ticket ticket_new1 = TicketFactory.getTicket("北京", "上海");`
	`16`	`+ ticket_new1.showTicketInfo("上铺");`
	`17`	`+`
	`18`	`+ Ticket ticket_new2 = TicketFactory.getTicket("北京", "杭州");`
	`19`	`+ ticket_new2.showTicketInfo("下铺");`
	`20`	`+`
	`21`	`+ Ticket ticket_cache1 = TicketFactory.getTicket("北京", "上海");`
	`22`	`+ ticket_cache1.showTicketInfo("下铺");`
	`23`	`+`
	`24`	`+ Ticket ticket_cache2 = TicketFactory.getTicket("北京", "杭州");`
	`25`	`+ ticket_cache2.showTicketInfo("下铺");`
	`26`	`+`
	`27`	`+ }`
	`28`	`+}`

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	`1`	`+package com.ruoxu.pattern.flyweight;`
	`2`	`+`
	`3`	`+public interface Ticket {`
	`4`	`+ void showTicketInfo(String bunk);`
	`5`	`+}`

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	`1`	`+package com.ruoxu.pattern.flyweight;`
	`2`	`+`
	`3`	`+import java.util.Map;`
	`4`	`+import java.util.concurrent.ConcurrentHashMap;`
	`5`	`+`
	`6`	`+public class TicketFactory {`
	`7`	`+ private static Map<String,Ticket> sTicketMap = new ConcurrentHashMap<>();`
	`8`	`+ public static Ticket getTicket(String from,String to){`
	`9`	`+ String key = from + "-" + to;`
	`10`	`+ if(sTicketMap.containsKey(key)){`
	`11`	`+ System.out.println("使用缓存==>" + key );`
	`12`	`+ return sTicketMap.get(key);`
	`13`	`+ }else{`
	`14`	`+ System.out.println("创建对象==>" + key);`
	`15`	`+ Ticket ticket = new TrainTicket(from, to);`
	`16`	`+ sTicketMap.put(key, ticket);`
	`17`	`+ return ticket;`
	`18`	`+ }`
	`19`	`+ }`
	`20`	`+}`

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	`1`	`+package com.ruoxu.pattern.flyweight;`
	`2`	`+`
	`3`	`+import java.util.Random;`
	`4`	`+`
	`5`	`+public class TrainTicket implements Ticket{`
	`6`	`+ public String from;`
	`7`	`+ public String to;`
	`8`	`+ public String bunk;// 铺位`
	`9`	`+ public int price;`
	`10`	`+`
	`11`	`+ public TrainTicket(String from,String to) {`
	`12`	`+ this.from = from;`
	`13`	`+ this.to = to;`
	`14`	`+ }`
	`15`	`+`
	`16`	`+ @Override`
	`17`	`+ public void showTicketInfo(String bunk) {`
	`18`	`+ price = new Random().nextInt(300);`
	`19`	`+ System.out.println("购买从 " + from + " 到 "+ to + " 的 " + bunk + " 火车票" + ",价格: " + price);`
	`20`	`+ }`
	`21`	`+`
	`22`	`+}`

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