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java 24种设计模式 含代码 java 24种设计模式 含代码

      <p>Builder的具体实现ConcreteBuilder:<br>
        通过具体完成接口Builder来构建或装配产品的部件;<br>
        定义并明确它所要创建的是什么具体东西;<br>
        提供一个可以重新获取产品的接口:</p>
      <table width="80%" border="0" cellspacing="3" cellpadding="3">
        <tr> 
          <td bgcolor="#CCCCCC"> 
            <p>public class ConcreteBuilder implements Builder { </p>
            <p>　　Part partA, partB, partC; <br>
              　　public void buildPartA() {<br>
              　　　　//这里是具体如何构建partA的代码<br>
              <br>
              　　}; <br>
              　　public void buildPartB() { <br>
              　　　　//这里是具体如何构建partB的代码<br>
              　　}; <br>
              　　 public void buildPartC() { <br>
              　　　　//这里是具体如何构建partB的代码<br>
              　　}; <br>
              　　 public Product getResult() { <br>
              　　　　//返回最后组装成品结果<br>
              　　}; <br>
            </p>
            <p> }</p>
          </td>
        </tr>
      </table>
      <p>复杂对象:产品Product:<br>
      </p>
      <table width="80%" border="0" cellspacing="3" cellpadding="3">
        <tr> 
          <td bgcolor="#CCCCCC">public interface Product { } </td>
        </tr>
      </table>
      <p>复杂对象的部件:</p>
      <table width="80%" border="0" cellspacing="3" cellpadding="3">
        <tr> 
          <td bgcolor="#CCCCCC">public interface Part { }</td>
        </tr>
      </table>
      <p><br>
        我们看看如何调用Builder模式:<br>
        ConcreteBuilder builder = new ConcreteBuilder();<br>
        Director director = new Director( builder ); <br>
        <br>
        director.construct(); <br>
        Product product = builder.getResult(); </p>
                  <p><b>Builder模式的应用<br>
        </b>在Java实际使用中,我们经常用到&quot;池&quot;(Pool)的概念,当资源提供者无法提供足够的资源,并且这些资源需要被很多用户反复共享时,就需要使用池.</p>
      <p>&quot;池&quot;实际是一段内存,当池中有一些复杂的资源的&quot;断肢&quot;(比如数据库的连接池,也许有时一个连接会中断),如果循环再利用这些&quot;断肢&quot;,将提高内存使用效率,提高池的性能.修改Builder模式中Director类使之能诊断&quot;断肢&quot;断在哪个部件上,再修复这个部件.</p>
      <p>具体英文文章见:<a href="http://www.javaworld.com/javaworld/javatips/jw-javatip78-p2.html#resources" target="_blank">Recycle 
        broken objects in resource pools<br>
        </a> </p>
      <p>设计模式如何在具体项目中应用见<a href="../mybook/index.htm" target="_blank">《Java实用系统开发指南》</a></p>
      <p>&nbsp;</p>
      <p>&nbsp;</p>
      <p>&nbsp;</p>
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