一行“神奇”的代码

 最近在复习闫宏的《Java与模式》，在介绍责任链模式的时候文中使用了红楼中“击鼓传花”的例子。以前只是粗略的翻阅了一下，没有仔细的看其中的源码。今天仔细看了其中的代码，发现一个令人疑惑的地方，这行代码如下:  

 

Player player = new JiaMu(new JiaZeng(new JiaBaoyu(new JiaHuan())));

 

刚开始感觉很神奇，但是仔细看了类图才明白这一串的new后面的对象都是继承于一个Player类。Player提供了一个构造方法：

class Player {
 private Player player;

 public Player(Player player) {
  this.player = player;
 }
}

 

按原来的结构，重新写了一个只与这行“神奇”代码相关的类，如下所示：

class JiaMu extends Player {
 public JiaMu(Player player) {
  super(player);
  System.out.println(" 贾母传花ing...");
 }
}

class JiaZeng extends Player {
 public JiaZeng(Player player) {
  super(player);
  System.out.println(" 贾政传花ing...");
 }
}

class JiaBaoyu extends Player {
 public JiaBaoyu(Player player) {
  super(player);
  System.out.println(" 贾宝玉传花ing...");
 }
}

class JiaHuan extends Player {
 public JiaHuan(Player player) {
  super(player);
  System.out.println(" 贾环传花ing...");
 }
}

public class Test {

 public static void main(String[] args) {
  Player player = new JiaMu(new JiaZeng(new JiaBaoyu(new JiaHuan(null))));
 }
}

 

此时才知道自己也有些浮躁了，“路漫漫其修远兮，吾将上下而求索”，此时备感深刻。

 

“海纳百川，有容乃大，壁立千仞，无欲则刚。”

 

补充：

new JiaMu(new JiaZeng(new JiaBaoyu(new JiaHuan(null))));

 

该代码在此文责任链中的作用为：JiaMu后面的传花人为JiaZeng，jiaZeng后面的传花人为JiBaoyu，jiaBaoyu后面的传花人为JiaHuan，JiaHuan后面没有人接应，所以为null。