J2EE应用开发心得(3) ——架构理解

mariolw 发表于 2011-12-21 08:44

1.struts <div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; line-height: 1.5; "> 现在用的比较多的ssh架构，即spring+struts+hibernate，我用了后两种，struts用的是1代，主要就是处理表单的信息获取、验证、以及信息输出，很多常见的逻辑都不需要自己去设计代码结构，遵循他设定好的思路就行了。最简单的一个例子：<div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; line-height: 1.5; "> 一个表单中有一个文本输入框、一个提交按钮，输入文字，点击按钮，自动跳到另一页，把输入的文字显示出来，有输入则显示输入文字，没输入则显示error。这样一个功能，用struts实现的话有以下几个文件：</div></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; line-height: 1.5; "> </div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; line-height: 1.5; ">hello.jsp</div><div id="codeText" class="codeText" style="margin-top: 0px; margin-right: 0px; margin-bottom: 1.1em; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; border-top-width: 1px; border-right-width: 1px; border-bottom-width: 1px; border-left-width: 1px; border-top-style: solid; border-right-style: solid; border-bottom-style: solid; border-left-style: solid; border-top-color: rgb(221, 221, 221); border-right-color: rgb(221, 221, 221); border-bottom-color: rgb(221, 221, 221); border-left-color: rgb(221, 221, 221); width: 646px; overflow-x: auto; overflow-y: auto; word-break: break-all; letter-spacing: 0.1px; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); font: normal normal normal 12px/normal Consolas, monospace; line-height: 1.5; "><ol start="1" class="dp-css" style="margin-top: 0px; margin-right: 1px; margin-bottom: 0px; margin-left: 0px; padding-top: 5px; padding-right: 0px; padding-bottom: 5px; padding-left: 0px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.3; color: rgb(92, 92, 92); background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; "><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; "><html:form action="/hello"> </li><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; "><p><html:submit>login</html:submit></p> </li><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; "></html:form></li></ol></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; line-height: 1.5; ">success.jsp</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; line-height: 1.5; "><div id="codeText" class="codeText" style="margin-top: 0px; margin-right: 0px; margin-bottom: 1.1em; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; border-top-width: 1px; border-right-width: 1px; border-bottom-width: 1px; border-left-width: 1px; border-top-style: solid; border-right-style: solid; border-bottom-style: solid; border-left-style: solid; border-top-color: rgb(221, 221, 221); border-right-color: rgb(221, 221, 221); border-bottom-color: rgb(221, 221, 221); border-left-color: rgb(221, 221, 221); width: 646px; overflow-x: auto; overflow-y: auto; word-break: break-all; letter-spacing: 0.1px; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); font: normal normal normal 12px/normal Consolas, monospace; line-height: 1.5; background-position: initial initial; background-repeat: initial initial; "><ol start="1" class="dp-css" style="margin-top: 0px; margin-right: 1px; margin-bottom: 0px; margin-left: 0px; padding-top: 5px; padding-right: 0px; padding-bottom: 5px; padding-left: 0px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.3; color: rgb(92, 92, 92); background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; "><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; "><bean:wirte name="result"/></li></ol></div></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; line-height: 1.5; ">error.jsp</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; line-height: 1.5; "><div id="codeText" class="codeText" style="margin-top: 0px; margin-right: 0px; margin-bottom: 1.1em; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; border-top-width: 1px; border-right-width: 1px; border-bottom-width: 1px; border-left-width: 1px; border-top-style: solid; border-right-style: solid; border-bottom-style: solid; border-left-style: solid; border-top-color: rgb(221, 221, 221); border-right-color: rgb(221, 221, 221); border-bottom-color: rgb(221, 221, 221); border-left-color: rgb(221, 221, 221); width: 646px; overflow-x: auto; overflow-y: auto; word-break: break-all; letter-spacing: 0.1px; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); font: normal normal normal 12px/normal Consolas, monospace; line-height: 1.5; background-position: initial initial; background-repeat: initial initial; "><ol start="1" class="dp-css" style="margin-top: 0px; margin-right: 1px; margin-bottom: 0px; margin-left: 0px; padding-top: 5px; padding-right: 0px; padding-bottom: 5px; padding-left: 0px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.3; color: rgb(92, 92, 92); background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; "><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; ">Error!</li></ol></div></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; line-height: 1.5; ">struts-config.xml</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; line-height: 1.5; "> </div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; line-height: 1.5; "><div id="codeText" class="codeText" style="margin-top: 0px; margin-right: 0px; margin-bottom: 1.1em; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; border-top-width: 1px; border-right-width: 1px; border-bottom-width: 1px; border-left-width: 1px; border-top-style: solid; border-right-style: solid; border-bottom-style: solid; border-left-style: solid; border-top-color: rgb(221, 221, 221); border-right-color: rgb(221, 221, 221); border-bottom-color: rgb(221, 221, 221); border-left-color: rgb(221, 221, 221); width: 646px; overflow-x: auto; overflow-y: auto; word-break: break-all; letter-spacing: 0.1px; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); font: normal normal normal 12px/normal Consolas, monospace; line-height: 1.5; background-position: initial initial; background-repeat: initial initial; "><ol start="1" class="dp-css" style="margin-top: 0px; margin-right: 1px; margin-bottom: 0px; margin-left: 0px; padding-top: 5px; padding-right: 0px; padding-bottom: 5px; padding-left: 0px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.3; color: rgb(92, 92, 92); background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; "><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; "><struts-config> </li><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; ">  <form-beans> </li><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; ">         <form-bean name="HelloForm" type="HelloForm"/> </li><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; ">  </form-beans> </li><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; ">  </li><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; "><action-mappings> </li><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; ">        <action path="/hello" type="HelloAction" name="HelloForm"> </li><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; ">            <forward name="success" path="/success.jsp"/> </li><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; ">              <forward name="error" path="/error.jsp"/> </li><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; ">        </action> </li><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; "></action-mappings></li></ol></div></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; line-height: 1.5; ">   上面的根据配置文件里面的定义，有个叫HelloForm的类对应路径为/hello的这个动作提交上来的表单，而hello.jsp里面的表单，正式对应了这个动作，同时配置文件还指出，用HelloAction这个类来接收表单并且处理逻辑，最后根据表单的内容决定跳转到哪个页。如果有输入内容，则跳转到/success.jsp，如果没有则跳转到/error.jsp.（顺便说下，感觉j2ee里面有好多东西，传递参数都是通过一个字符串作为参数名的，挺有意思的。和编译器一样，应用服务器也经常要做些字符串解析的事情吧。）</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; line-height: 1.5; ">    说到这里，再把上面提到的两个类，HelloForm和HelloAction贴出来：</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; line-height: 1.5; ">HelloForm.java</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; line-height: 1.5; "><div id="codeText" class="codeText" style="margin-top: 0px; margin-right: 0px; margin-bottom: 1.1em; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; border-top-width: 1px; border-right-width: 1px; border-bottom-width: 1px; border-left-width: 1px; border-top-style: solid; border-right-style: solid; border-bottom-style: solid; border-left-style: solid; border-top-color: rgb(221, 221, 221); border-right-color: rgb(221, 221, 221); border-bottom-color: rgb(221, 221, 221); border-left-color: rgb(221, 221, 221); width: 658px; overflow-x: auto; overflow-y: auto; word-break: break-all; letter-spacing: 0.1px; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); font: normal normal normal 12px/normal Consolas, monospace; line-height: 1.5; background-position: initial initial; background-repeat: initial initial; "><ol start="1" class="dp-css" style="margin-top: 0px; margin-right: 1px; margin-bottom: 0px; margin-left: 0px; padding-top: 5px; padding-right: 0px; padding-bottom: 5px; padding-left: 0px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.3; color: rgb(92, 92, 92); background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; "><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; ">import org.apache.struts.action.ActionForm; </li><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; "> </li><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; ">public class LoginForm extends ActionForm { </li><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; ">    private static final long serialVersionUID = 1L; </li><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; ">    private String hello = ""; </li><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; ">    public String getHello(){ </li><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; ">        return this.hello; </li><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; ">} </li><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; ">    public void setHello(String s) { </li><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; ">        this.hello = s; </li><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; ">    } </li><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; ">}</li></ol></div></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; line-height: 1.5; ">HelloAction.java</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; line-height: 1.5; "><div id="codeText" class="codeText" style="margin-top: 0px; margin-right: 0px; margin-bottom: 1.1em; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; border-top-width: 1px; border-right-width: 1px; border-bottom-width: 1px; border-left-width: 1px; border-top-style: solid; border-right-style: solid; border-bottom-style: solid; border-left-style: solid; border-top-color: rgb(221, 221, 221); border-right-color: rgb(221, 221, 221); border-bottom-color: rgb(221, 221, 221); border-left-color: rgb(221, 221, 221); width: 658px; overflow-x: auto; overflow-y: auto; word-break: break-all; letter-spacing: 0.1px; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); font: normal normal normal 12px/normal Consolas, monospace; line-height: 1.5; background-position: initial initial; background-repeat: initial initial; "><ol start="1" class="dp-css" style="margin-top: 0px; margin-right: 1px; margin-bottom: 0px; margin-left: 0px; padding-top: 5px; padding-right: 0px; padding-bottom: 5px; padding-left: 0px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.3; color: rgb(92, 92, 92); background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; "><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; ">import org.apache.struts.action.*; </li><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; ">import javax.servlet.http.*; </li><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; "> </li><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; ">public class HelloAction extends Action { </li><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; ">    public ActionForward execute(ActionMapping actionMapping, </li><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; ">            ActionForm actionForm, HttpServletRequest request, </li><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; ">            HttpServletResponse response) throws Exception { </li><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; ">      </li><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; ">        HelloForm form = (HelloForm) actionForm; </li><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; ">        if("".equal(form.getHello()) </li><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; ">      return actionMapping.findForward("error"); </li><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; ">        else </li><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; ">            return actionMapping.findForward("success"); </li><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; ">      } </li><li style="margin-top: 1px; margin-right: 1px; margin-bottom: 1px; margin-left: 1px; padding-top: 1px; padding-right: 1px; padding-bottom: 1px; padding-left: 10px; list-style-type: decimal; list-style-position: outside; list-style-image: none; line-height: 1.5; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); background-position: initial initial; background-repeat: initial initial; ">}</li></ol></div></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; line-height: 1.5; ">这样所有必须的文件就都有了，struts是一个独立于tomcat的工具，要让他工作起来，一方面要配置tomact的web.xml，截获http请求，另外一方面就是要把相应的库放在正确的位置，这些可以参考网上的教程。</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; line-height: 1.5; "> </div>2.Hibernate<div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; line-height: 1.5; "> Hibernate是一个专门用于处理数据库操作的工具，配置文件有一个全局的xml配置为文件，数据库里面每个表对应一个POJO也就是一个类，同时也对应一个解释自己以及与其他表之间数据关系的配置文件。</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; line-height: 1.5; ">所有的配置文件以及POJO类，都可以用自动化的工具生成，这类工具具有反向工程的能力，开发时先用数据库工具设计好表、关系，再用这些工具连接数据库后根据数据库中的关系，生成配置文件和POJO类，当数据库发生变化时，只需要重新自动生成一次就行了，十分方便，例如eclipse的插件HibernateTool就十分好用。</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; line-height: 1.5; "> 以上步骤完成后，为了封装逻辑操作，一般都要编写一些DAO（Date Access Object），把常用的操作以方法的形式实现，这样在struts的Action里面只需要调用DAO就可以了，而一般不需要关注更底层的数据结构。</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; line-height: 1.5; "> 其实DAO和Hibernate没有什么联系，以前不用Hibernate时，DAO中的代码比较复杂，有很多SQL语句，并且要设定和保持和数据库的连接。有了Hibernate只有，DAO中的代码就简化了许多，只要获取Hibernate和数据库建立的session，在这个session中针对POJO对象操作即可，不需要控制数据库连接，也不需要使用SQL语句。当然，在遇到某些特殊问题、或者考虑到效率时，不得不用SQL语句；针对这个问题，Hibernate设计了一种HQL语句，与SQL类似，其优越之处在于可以在语句中使用面向对象的概念，从而在复杂数据关系中，大大简化了查询语句。此外，Hibernate也支持SQL原语查询。</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; line-height: 1.5; "> 在我的项目里，一般针对单条记录用面向对象操作比较方便，涉及到复杂条件查询多条记录以及排序时，往往用HQL语句比较方便。</div>

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