观察者模式

设计模式的意义在于：面向业务内容、业务数据结构和系统架构，高内聚低耦合、优雅的将平面逻辑立体化。

  1 package designPattern;
  2 
  3 import java.util.ArrayList;
  4 import java.util.List;
  5 /**
  6  * 观察者模式
  7  * @author Administrator
  8  */
  9 public class B19_ObserverTest {
 10 
 11     /**
 12      * 定义对象间的一种一对多的依赖关系,当一个对象的状态发生改变时,所有依赖于它的对象都得到通知并被自动更新。
 13      */
 14     public static void main(String[] args) {
 15         Policeman huangpuPoliceman=new HuangPuPoliceman();
 16         Policeman tianhePoliceman=new TianHePoliceman();
 17         Citizen c1=new HuangPuCitizen();
 18         Citizen c2=new TianHeCitizen();
 19         
 20         c1.register(huangpuPoliceman);
 21         c1.register(tianhePoliceman);
 22         c1.sendMessage("normal");
 23         
 24         c2.register(tianhePoliceman);
 25         c2.sendMessage("unnormal");
 26     }
 27 }
 28 //subject 目标知道它的观察者。可以有任意多个观察者观察同一个目标。提供注册和删除观察者对象的接口。
 29 abstract class Citizen {
 30     
 31     @SuppressWarnings("rawtypes")
 32     List pols;
 33     
 34     String help = "normal";
 35     
 36     public void setHelp(String help) {
 37         this.help = help;
 38     }
 39     
 40     public String getHelp() {
 41         return this.help;
 42     }
 43     
 44     abstract void sendMessage(String help);
 45 
 46     @SuppressWarnings("rawtypes")
 47     public void setPolicemen() {
 48         this.pols = new ArrayList();
 49     }
 50     
 51     @SuppressWarnings("unchecked")
 52     public void register(Policeman pol) {
 53         this.pols.add(pol);
 54     }
 55 
 56     public void unRegister(Policeman pol) {
 57         this.pols.remove(pol);
 58     }
 59 }
 60 //observer
 61 interface Policeman {
 62 
 63     void action(Citizen ci);
 64 }
 65 //concreteSubject
 66 class HuangPuCitizen extends Citizen {
 67 
 68     public HuangPuCitizen() {
 69         setPolicemen();
 70     }
 71      
 72     public HuangPuCitizen(Policeman pol) {
 73         setPolicemen();
 74         register(pol);
 75     }
 76     
 77     public void sendMessage(String help) {
 78         setHelp(help);
 79         for(int i = 0; i < pols.size(); i++) {
 80             Policeman pol = (Policeman)pols.get(i);
 81             //通知警察行动
 82             pol.action(this);
 83         }
 84     }
 85 }
 86 class TianHeCitizen extends Citizen {
 87     public TianHeCitizen() {
 88         setPolicemen();
 89     }
 90     
 91     public TianHeCitizen(Policeman pol) {
 92         setPolicemen();
 93         register(pol);
 94     }
 95     
 96     public void sendMessage(String help) {
 97         setHelp(help);
 98         for (int i = 0; i < pols.size(); i++) {
 99             Policeman pol =(Policeman)pols.get(i);
100             //通知警察行动
101             pol.action(this);
102         }
103     }
104 }
105 
106 //concreteObserver
107 class HuangPuPoliceman implements Policeman {
108 
109     public void action(Citizen ci) {
110         String help = ci.getHelp();
111         if (help.equals("normal")) {
112             System.out.println("黄埔警察：一切正常, 不用出动");
113         }
114         if (help.equals("unnormal")) {
115             System.out.println("有犯罪行为, 黄埔警察出动!");
116         }
117     }
118 }
119 class TianHePoliceman implements Policeman {
120 
121     public void action(Citizen ci) {
122         String help = ci.getHelp();
123         if (help.equals("normal")) {
124             System.out.println("天河警察：一切正常, 不用出动");
125         }
126         if (help.equals("unnormal")) {
127             System.out.println("有犯罪行为, 天河警察出动!");
128         }
129     }
130 }

 

环境：JDK1.6，MAVEN，tomcat，eclipse

源码地址：https://files.cnblogs.com/files/xiluhua/designPattern.rar

欢迎亲们评论指教。

posted @ 2015-04-10 10:15  xiluhua  阅读(206)  评论(0)  编辑  收藏  举报