Spring之代理设计模式原理与代码展示

怼烎@ 2022-06-04 05:11 98阅读 0赞

1.代理设计模式

**代理设计模式的原理：使用一个代理将对象包装起来，然后用该代理对象取代原始对象。任何对原始对象的调用都要通过代理。代理对象决定是否以及何时将方法调用转到原始对象上。**

- GoF95  一共定义了23种设计模式.代理设计模式是非常重要模式之一.

- 作用:

**- 对目标对象访问进行控制.在访问目标前,后进行功能的扩展.**

- 可以进行功能扩展的技术:

- 过滤器

- 拦截器

- 代理

- …

2- 代理方式:

- 静态代理:只能代理一种类型的对象.代理类需要自定义开发.

- 动态代理: **可以代理所有的类型对象.代理类由代理工具类动态生成.**

- **JDK动态代理**

\- 基于接口进行代理.

- 目标对象必须实现相关的接口,才能使用这种代理方式.

- 代理类和目标类实现了共同的接口.

- InvocationHandler

**- Cglib/Javassist**

- 基于继承方式进行代理的.

- 代理类是目标类的子类.

3- 代理流程:

- 使用代理前代码结构:

- A(客户端) -> D(目标程序(业务代码+非业务代码(日志,事务,权限,校验…)))

- 使用代理后代码结构:

- A(客户端) ->B(代理对象) ->C(调用处理器(非业务代码(日志,事务,权限,校验…))-> D(目标程序(业务代码))

4- 代理可以解决系统中哪些问题?

- 日志打印,事务处理,权限控制,数据校验…

**2.代理设计模式的使用案例**

1.定义目标类接口

<table style="border:1pt solid rgb(163,163,163); border-collapse:collapse; direction:ltr; margin-left:0.333in; width:338px">    
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   <td style="border:1pt solid rgb(163,163,163); padding:2pt 3pt; vertical-align:top"> 
    <div style="margin:0in; font-size:14px"> 
     <span style="font-family:微软雅黑">public interface MathCalculator { </span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">int add(int i,int j);</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">int sub(int i,int j);</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">int mul(int i, int j);</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">int div(int i,int j);</span> 
    </div> 
    <div style="margin:0in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">}</span> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

2.定义目标类

<table style="border:1pt solid rgb(163,163,163); border-collapse:collapse; direction:ltr; margin-left:0.333in; width:524px">    
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   <td style="border:1pt solid rgb(163,163,163); padding:2pt 3pt; vertical-align:top"> 
    <div style="margin:0in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">//如何增加日志扩展</span> 
    </div> 
    <div style="margin:0in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">//如果在已有的业务代码中增加日志扩展代码,不好:</span> 
    </div> 
    <div style="margin:0in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">//业务代码和非业务代码进行耦合.不利于维护.日志代码 属于重复性代码.</span> 
    </div> 
    <div style="margin:0in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">//目标类</span> 
    </div> 
    <div style="margin:0in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">public class EazyImpl implements MathCalculator{ </span> 
    </div> 
    <div style="margin:0in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">&nbsp;</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">@Override</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">public int add(int i, int j) { </span> 
    </div> 
    <div style="margin:0in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">&nbsp;</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">int result = i + j;</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">&nbsp;</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">System.out.println("方法内部打印：result="+result);</span> 
    </div> 
    <div style="margin:0in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">&nbsp;</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">return result;</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">}</span> 
    </div> 
    <div style="margin:0in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">&nbsp;</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">@Override</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">public int sub(int i, int j) { </span> 
    </div> 
    <div style="margin:0in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">&nbsp;</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">int result = i - j;</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">&nbsp;</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">System.out.println("方法内部打印：result="+result);</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">&nbsp;</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">return result;</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">}</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">@Override</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">public int mul(int i, int j) { </span> 
    </div> 
    <div style="margin:0in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">&nbsp;</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">int result = i * j;</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">&nbsp;</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">System.out.println("方法内部打印：result="+result);</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">&nbsp;</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">return result;</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">}</span> 
    </div> 
    <div style="margin:0in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">&nbsp;</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">@Override</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">public int div(int i, int j) { </span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">int result = i / j;</span> 
     <span style="font-family:微软雅黑; font-size:10.5pt">&nbsp;</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">System.out.println("方法内部打印：result="+result);</span> 
     <span style="font-family:微软雅黑; font-size:10.5pt">&nbsp;</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">return result;</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">}</span> 
    </div> 
    <div style="margin:0in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">&nbsp;</span> 
    </div> 
    <div style="margin:0in; font-size:14px"> 
     <span style="font-family:微软雅黑">}</span> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

3.定义工具类

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    <div style="margin:0in; font-size:14px"> 
     <span style="font-family:微软雅黑">//工具类:用于动态生成代理对象.</span> 
    </div> 
    <div style="margin:0in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">public class ProxyProvider { </span> 
    </div> 
    <div style="margin:0in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">&nbsp;</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">private Object targetObject ;</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">&nbsp;</span> 
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    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">public ProxyProvider(Object targetObject){ </span> 
    </div> 
    <div style="margin:0in 0in 0in 0.75in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">this.targetObject = targetObject ;</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">}</span> 
     <span style="font-family:微软雅黑; font-size:10.5pt">&nbsp;</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">//动态创建代理对象.</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">public Object getProxy(){ </span> 
    </div> 
    <div style="margin:0in 0in 0in 0.75in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">/**</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.75in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">&nbsp;</span> 
     <span style="font-size:10.5pt; font-family:微软雅黑">* ClassLoader loader</span> 
     <span style="font-size:10.5pt; font-family:微软雅黑">&nbsp;</span> 
     <span style="font-size:10.5pt; font-family:微软雅黑">: 类加载器</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.75in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">&nbsp;</span> 
     <span style="font-size:10.5pt; font-family:微软雅黑">* &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;用于加载代理类到JVM中运行.一般传递目标对象的类加载器就可以了.</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.75in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">&nbsp;</span> 
     <span style="font-size:10.5pt; font-family:微软雅黑">* Class&lt;?&gt;[] interfaces : 接口类型数组</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.75in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">&nbsp;</span> 
     <span style="font-size:10.5pt; font-family:微软雅黑">* &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;JDK动态代理,基于接口的. 目标类和代理类实现共同的接口.需要通过目标对象来获取接口类型</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.75in; font-size:14px"> 
     <span style="font-family:微软雅黑">&nbsp;</span> 
     <span style="font-family:微软雅黑">* InvocationHandler h : 调用处理器</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.75in; font-size:14px"> 
     <span style="font-family:微软雅黑">&nbsp;</span> 
     <span style="font-family:微软雅黑">* </span> 
     <span style="color:rgb(255,0,0); font-family:微软雅黑"><strong>代理类是在内存中动态生成的.无法将扩展代码写在代理类中.所以,需要通过InvocationHandler接口编写实现类,来完成功能扩展.</strong></span> 
    </div> 
    <div style="margin:0in 0in 0in 0.75in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">&nbsp;</span> 
     <span style="font-size:10.5pt; font-family:微软雅黑">*/</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.75in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑; color:red">return</span> 
     <span style="font-size:10.5pt; font-family:微软雅黑">Proxy.newProxyInstance(</span> 
    </div> 
    <div style="margin:0in 0in 0in 1.125in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">targetObject.getClass().getClassLoader(),</span> 
    </div> 
    <div style="margin:0in 0in 0in 1.125in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">targetObject.getClass().getInterfaces(),</span> 
    </div> 
    <div style="margin:0in 0in 0in 1.125in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">new</span> 
     <span style="font-size:10.5pt; font-family:微软雅黑; color:red">InvocationHandler</span> 
     <span style="font-size:10.5pt; font-family:微软雅黑">(){ </span> 
    </div> 
    <div style="margin:0in 0in 0in 1.5in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">/**</span> 
    </div> 
    <div style="margin:0in 0in 0in 1.5in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">&nbsp;</span> 
     <span style="font-size:10.5pt; font-family:微软雅黑">* Object proxy : 代理对象</span> 
    </div> 
    <div style="margin:0in 0in 0in 1.5in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">&nbsp;</span> 
     <span style="font-size:10.5pt; font-family:微软雅黑">* Method method : 调用目标方法对象</span> 
    </div> 
    <div style="margin:0in 0in 0in 1.5in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">&nbsp;</span> 
     <span style="font-size:10.5pt; font-family:微软雅黑">* Object[] args : 调用目标方法的参数</span> 
    </div> 
    <div style="margin:0in 0in 0in 1.5in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">&nbsp;</span> 
     <span style="font-size:10.5pt; font-family:微软雅黑">*/</span> 
    </div> 
    <div style="margin:0in 0in 0in 1.5in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">@Override</span> 
    </div> 
    <div style="margin:0in 0in 0in 1.5in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">public Object invoke(Object proxy, Method method, Object[] args)throws Throwable { </span> 
    </div> 
    <div style="margin:0in 0in 0in 1.875in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">Object result = null ;</span> 
    </div> 
    <div style="margin:0in 0in 0in 1.875in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">try { </span> 
     <span style="font-family:微软雅黑; font-size:10.5pt">//扩展日志</span> 
    </div> 
    <div style="margin:0in 0in 0in 2.25in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">System.out.println("[</span> 
     <span style="font-size:10.5pt; font-family:&quot;Segoe UI Symbol&quot;">★</span> 
     <span style="font-size:10.5pt; font-family:微软雅黑">日志]["+method.getName()+"方法开始][参数值：</span> 
    </div> 
    <div style="margin:0in 0in 0in 2.25in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;"+(args==null?"":Arrays.asList(args))+"]");</span> 
    </div> 
    <div style="margin:0in 0in 0in 2.25in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">&nbsp;</span> 
    </div> 
    <div style="margin:0in 0in 0in 2.25in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">//执行目标</span> 
    </div> 
    <div style="margin:0in 0in 0in 2.25in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">result = method.invoke(targetObject, args);</span> 
    </div> 
    <div style="margin:0in 0in 0in 2.25in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">&nbsp;</span> 
    </div> 
    <div style="margin:0in 0in 0in 2.25in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">//扩展日志</span> 
    </div> 
    <div style="margin:0in 0in 0in 2.25in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">System.out.println("[</span> 
     <span style="font-size:10.5pt; font-family:&quot;Segoe UI Symbol&quot;">★</span> 
     <span style="font-size:10.5pt; font-family:微软雅黑">日志]["+method.getName()+"方法结束][返回值："+result+"]");</span> 
    </div> 
    <div style="margin:0in 0in 0in 1.875in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">} catch (Exception e) { </span> 
    </div> 
    <div style="margin:0in 0in 0in 2.25in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">//扩展日志</span> 
    </div> 
    <div style="margin:0in 0in 0in 2.25in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">e.printStackTrace();</span> 
    </div> 
    <div style="margin:0in 0in 0in 2.25in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">Throwable cause = e.getCause();</span> 
    </div> 
    <div style="margin:0in 0in 0in 2.25in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">if(cause!=null){ </span> 
    </div> 
    <div style="margin:0in 0in 0in 2.625in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">System.out.println("[</span> 
     <span style="font-size:10.5pt; font-family:&quot;Segoe UI Symbol&quot;">★</span> 
     <span style="font-size:10.5pt; font-family:微软雅黑">日志]["+method.getName()+"方法异常了][异常消息："+cause.getMessage()+"]");&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span> 
    </div> 
    <div style="margin:0in 0in 0in 2.25in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">}</span> 
    </div> 
    <div style="margin:0in 0in 0in 1.875in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">} finally{ </span> 
    </div> 
    <div style="margin:0in 0in 0in 2.25in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">//扩展日志</span> 
    </div> 
    <div style="margin:0in 0in 0in 2.25in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">System.out.println("[</span> 
     <span style="font-size:10.5pt; font-family:&quot;Segoe UI Symbol&quot;">★</span> 
     <span style="font-size:10.5pt; font-family:微软雅黑">日志]["+method.getName()+"方法最终结束了]");</span> 
    </div> 
    <div style="margin:0in 0in 0in 1.875in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">}</span> 
    </div> 
    <div style="margin:0in 0in 0in 1.875in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">&nbsp;</span> 
    </div> 
    <div style="margin:0in 0in 0in 1.875in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">return result;</span> 
    </div> 
    <div style="margin:0in 0in 0in 1.5in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">}</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.75in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">});</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">}</span> 
    </div> 
    <div style="margin:0in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">}</span> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

4.定义测试类

<table style="border:1pt solid rgb(163,163,163); border-collapse:collapse; direction:ltr; margin-left:0.333in; width:694px">    
 <tbody> 
  <tr> 
   <td style="border:1pt solid rgb(163,163,163); padding:2pt 3pt; vertical-align:top"> 
    <div style="margin:0in; font-size:14px"> 
     <span style="font-family:微软雅黑">public static void main(String[] args) { </span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">&nbsp;</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">MathCalculator calculator = new EazyImpl(); //目标对象</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">calculator.add(10, 5);</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">calculator.sub(10, 5);</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">calculator.mul(10, 5);</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">calculator.div(10, 5);</span> 
     <span style="font-family:微软雅黑; font-size:10.5pt">&nbsp;</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">System.out.println("------------------------------");</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">&nbsp;</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">//通过工具类来创建代理对象</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">//代理对象的类名:</span> 
     <span style="font-size:10.5pt; font-family:微软雅黑; color:red">$Proxy + 数字</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">Object proxyObject = new ProxyProvider(calculator).getProxy();</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">&nbsp;</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑; color:rgb(227,0,0)"><strong>//A(客户端) -&gt; B(代理程序) -&gt; C(InvocationHandler(日志打印)) -&gt; D(目标程序)</strong></span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">MathCalculator proxy = (MathCalculator)proxyObject;</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">proxy.add(10, 5);</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">proxy.sub(10, 5);</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">proxy.mul(10, 5);</span> 
    </div> 
    <div style="margin:0in 0in 0in 0.375in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">proxy.div(10, 0);</span> 
    </div> 
    <div style="margin:0in; font-size:10.5pt"> 
     <span style="font-size:10.5pt; font-family:微软雅黑">}</span> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>