data-mapper && Decorator

way2wonder · Aug 3, 2016 · 0f13239 · 0f13239
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diff --git a/java_design_pattern.md b/java_design_pattern.md
@@ -38,3  38,87 @@
 * the algorithm for creating a complex object should be independent of the parts that make up the object and how they're assembled  （构造分离）
 * the construction process must allow different representations for the object that's constructed（构造器必须允许对象的不同表现形式）
 ![Builder](./pictures/builder_1.png)
 
 
 
 ### Multiton  （多例，又叫Registry）
 **使用场景：**
 
 * Ensure a class only has limited number of instances, and provide a global point of access to them.（确保一个类只有有限的实例，切需要提供一个全局的入口用于获取他们）
 
 ![Builder](./pictures/multiton.png)
 
 
 ```java
   static {
     nazguls = new ConcurrentHashMap<>();
     nazguls.put(NazgulName.KHAMUL, new Nazgul(NazgulName.KHAMUL));
     nazguls.put(NazgulName.MURAZOR, new Nazgul(NazgulName.MURAZOR));
     nazguls.put(NazgulName.DWAR, new Nazgul(NazgulName.DWAR));
     nazguls.put(NazgulName.JI_INDUR, new Nazgul(NazgulName.JI_INDUR));
     nazguls.put(NazgulName.AKHORAHIL, new Nazgul(NazgulName.AKHORAHIL));
     nazguls.put(NazgulName.HOARMURATH, new Nazgul(NazgulName.HOARMURATH));
     nazguls.put(NazgulName.ADUNAPHEL, new Nazgul(NazgulName.ADUNAPHEL));
     nazguls.put(NazgulName.REN, new Nazgul(NazgulName.REN));
     nazguls.put(NazgulName.UVATHA, new Nazgul(NazgulName.UVATHA));
   }
 
   private Nazgul(NazgulName name) {
     this.name = name;
   }
 
   public static Nazgul getInstance(NazgulName name) {
     return nazguls.get(name);
   }
 ```
 
 代码中 `getInstance `中用的是map获取对象实例的，而不是用得new，这样的好处就是不用每次都去new一个实例。
 
 
 
 
 # Twin
 
 **使用场景：**  
 * Twin pattern is a design pattern which provides a standard solution to simulate multiple inheritance in java（实现多重继承的一种设计模式，java原本是不支持多重继承的）
 
 
 ---
 这3个设计模式没包含在difficulty里面
 
 * Aggregator Microservices
 * Message Channel
 * Publish Subscribe  
 
 
 ## CallBack  
 
 
 ![CallBack 设计模式](./pictures/callback.png)
 
 >jdk中的`CyclicBarrier` 
 	
 
 ## DAO （Data Access Object）
 ![](./pictures/dao.png)
 
 
 
 ## Data  Mapper
 ![](./pictures/data-mapper.png)
 
 
 ##  Decorator（Wrapper 装饰模式，或者叫包装模式）
 >  EX: `JDK中得IO流`  
 >  这里可以将IO流彻底的复习一下，顺便掌握一下NIO
 
 **使用场景：**
 
 * to add responsibilities to individual objects dynamically and transparently, that is, without affecting other objects
 * for responsibilities that can be withdrawn（撤离）
 * when extension by subclassing is impractical.（用子类扩展不现实） Sometimes a large number of independent extensions are possible and would produce an explosion of subclasses to support every combination. Or a class definition may be hidden or otherwise unavailable for subclassing（类定义被隐藏或者不能实现子类）
 
 
 
 
 
diff --git a/pictures/callback.png b/pictures/callback.png
diff --git a/pictures/dao.png b/pictures/dao.png
diff --git a/pictures/data-mapper.png b/pictures/data-mapper.png