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Struts2原理及简单实例

参考连接:

http://blog.csdn.net/laner0515/article/details/27692673/

http://www.cnblogs.com/sobne/articles/5443114.html

一、Struts2原理

设计目标

 

    Struts设计的第一目标就是使MVC模式应用于web程序设计。在这儿MVC模式的好处就不在提了。

 

技术优势

 

    Struts2有两方面的技术优势,一是所有的Struts2应用程序都是基于client/server HTTP交换协议,The Java Servlet API揭示了java Servlet只是Java API的一个很小子集,这样我们可以在业务逻辑部分使用功能强大的Java语言进行程序设计。

 

    二是提供了对MVC的一个清晰的实现,这一实现包含了很多参与对所以请求进行处理的关键组件,如:拦截器、OGNL表达式语言、堆栈。

 

 

 

    因为struts2有这样目标,并且有这样的优势,所以,这是我们学习struts2的理由,下面,我们在深入剖析一下struts的工作原理。

 

工作原理

 

    Suruts2的工作原理可以用下面这张图来描述,下面我们分步骤介绍一下每一步的核心内容

技术分享

一个请求在Struts2框架中的处理大概分为以下几个步骤 

    1、客户端初始化一个指向Servlet容器(例如Tomcat)的请求

    2、这个请求经过一系列的过滤器(Filter)(这些过滤器中有一个叫做ActionContextCleanUp的可选过滤器,这个过滤器对于Struts2和其他框架的集成很有帮助,例如:SiteMesh Plugin) 

    3、接着FilterDispatcher被调用,FilterDispatcher询问ActionMapper来决定这个请是否需要调用某个Action 

       FilterDispatcher是控制器的核心,就是mvc中c控制层的核心。下面粗略的分析下我理解的FilterDispatcher工作流程和原理:FilterDispatcher进行初始化并启用核心doFilter

 1 public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException ...{  
 2         HttpServletRequest request = (HttpServletRequest) req;  
 3         HttpServletResponse response = (HttpServletResponse) res;  
 4         ServletContext servletContext = filterConfig.getServletContext();  
 5         // 在这里处理了HttpServletRequest和HttpServletResponse。  
 6         DispatcherUtils du = DispatcherUtils.getInstance();  
 7         du.prepare(request, response);//正如这个方法名字一样进行locale、encoding以及特殊request parameters设置  
 8         try ...{  
 9             request = du.wrapRequest(request, servletContext);//对request进行包装  
10         } catch (IOException e) ...{  
11             String message = "Could not wrap servlet request with MultipartRequestWrapper!";  
12             LOG.error(message, e);  
13             throw new ServletException(message, e);  
14         }  
15                 ActionMapperIF mapper = ActionMapperFactory.getMapper();//得到action的mapper  
16         ActionMapping mapping = mapper.getMapping(request);// 得到action 的 mapping  
17         if (mapping == null) ...{  
18             // there is no action in this request, should we look for a static resource?  
19             String resourcePath = RequestUtils.getServletPath(request);  
20             if ("".equals(resourcePath) && null != request.getPathInfo()) ...{  
21                 resourcePath = request.getPathInfo();  
22             }  
23             if ("true".equals(Configuration.get(WebWorkConstants.WEBWORK_SERVE_STATIC_CONTENT))   
24                     && resourcePath.startsWith("/webwork")) ...{  
25                 String name = resourcePath.substring("/webwork".length());  
26                 findStaticResource(name, response);  
27             } else ...{  
28                 // this is a normal request, let it pass through  
29                 chain.doFilter(request, response);  
30             }  
31             // WW did its job here  
32             return;  
33         }  
34         Object o = null;  
35         try ...{  
36             //setupContainer(request);  
37             o = beforeActionInvocation(request, servletContext);  
38 //整个框架最最核心的方法,下面分析  
39             du.serviceAction(request, response, servletContext, mapping);  
40         } finally ...{  
41             afterActionInvocation(request, servletContext, o);  
42             ActionContext.setContext(null);  
43         }  
44     }  
45 du.serviceAction(request, response, servletContext, mapping);  
46 //这个方法询问ActionMapper是否需要调用某个Action来处理这个(request)请求,如果ActionMapper决定需要调用某个Action,FilterDispatcher把请求的处理交给ActionProxy  
47    
48 public void serviceAction(HttpServletRequest request, HttpServletResponse response, String namespace, String actionName, Map requestMap, Map parameterMap, Map sessionMap, Map applicationMap) ...{   
49         HashMap extraContext = createContextMap(requestMap, parameterMap, sessionMap, applicationMap, request, response, getServletConfig());  //实例化Map请求 ,询问ActionMapper是否需要调用某个Action来处理这个(request)请求  
50         extraContext.put(SERVLET_DISPATCHER, this);   
51         OgnlValueStack stack = (OgnlValueStack) request.getAttribute(ServletActionContext.WEBWORK_VALUESTACK_KEY);   
52         if (stack != null) ...{   
53             extraContext.put(ActionContext.VALUE_STACK,new OgnlValueStack(stack));   
54         }   
55         try ...{   
56             ActionProxy proxy = ActionProxyFactory.getFactory().createActionProxy(namespace, actionName, extraContext);   
57 //这里actionName是通过两道getActionName解析出来的, FilterDispatcher把请求的处理交给ActionProxy,下面是ServletDispatcher的 TODO:   
58             request.setAttribute(ServletActionContext.WEBWORK_VALUESTACK_KEY, proxy.getInvocation().getStack());   
59             proxy.execute();   
60          //通过代理模式执行ActionProxy  
61             if (stack != null)...{   
62                 request.setAttribute(ServletActionContext.WEBWORK_VALUESTACK_KEY,stack);   
63             }   
64         } catch (ConfigurationException e) ...{   
65             log.error("Could not find action", e);   
66             sendError(request, response, HttpServletResponse.SC_NOT_FOUND, e);   
67         } catch (Exception e) ...{   
68             log.error("Could not execute action", e);   
69             sendError(request, response, HttpServletResponse.SC_INTERNAL_SERVER_ERROR, e);   
70         }   
71 } 

4、如果ActionMapper决定需要调用某个Action,FilterDispatcher把请求的处理交给ActionProxy 

    5、ActionProxy通过ConfigurationManager询问框架的配置文件,找到需要调用的Action类 ,这里,我们一般是从struts.xml配置中读取。

    6、ActionProxy创建一个ActionInvocation的实例。

    7、ActionInvocation实例使用命名模式来调用,在调用Action的过程前后,涉及到相关拦截器(Intercepter)的调用。

    下面我们来看看ActionInvocation是如何工作的:

    ActionInvocation是Xworks 中Action 调度的核心。而对Interceptor 的调度,也正是由ActionInvocation负责。ActionInvocation 是一个接口,而DefaultActionInvocation 则是Webwork 对ActionInvocation的默认实现。

    Interceptor的调度流程大致如下:

    1.ActionInvocation初始化时,根据配置,加载Action相关的所有Interceptor。

    2. 通过ActionInvocation.invoke方法调用Action实现时,执行Interceptor。

    Interceptor将很多功能从我们的Action中独立出来,大量减少了我们Action的代码,独立出来的行为具有很好的重用性。XWork、WebWork的许多功能都是有Interceptor实现,可以在配置文件中组装Action用到的Interceptor,它会按照你指定的顺序,在Action执行前后运行。

    这里,我们简单的介绍一下Interceptor

    在struts2中自带了很多拦截器,在struts2-core-2.1.6.jar这个包下的struts-default.xml中我们可以发现:

 1 <interceptors>  
 2            <interceptor name="alias"class="com.opensymphony.xwork2.interceptor.AliasInterceptor"/>  
 3            <interceptor name="autowiring"class="com.opensymphony.xwork2.spring.interceptor.ActionAutowiringInterceptor"/>  
 4            <interceptor name="chain"class="com.opensymphony.xwork2.interceptor.ChainingInterceptor"/>  
 5            <interceptor name="conversionError"class="org.apache.struts2.interceptor.StrutsConversionErrorInterceptor"/>  
 6            <interceptor name="clearSession"class="org.apache.struts2.interceptor.ClearSessionInterceptor"/>  
 7            <interceptor name="createSession"class="org.apache.struts2.interceptor.CreateSessionInterceptor"/>  
 8            <interceptor name="debugging"class="org.apache.struts2.interceptor.debugging.DebuggingInterceptor"/>  
 9            <interceptor name="externalRef"class="com.opensymphony.xwork2.interceptor.ExternalReferencesInterceptor"/>  
10            <interceptor name="execAndWait"class="org.apache.struts2.interceptor.ExecuteAndWaitInterceptor"/>  
11            <interceptor name="exception"class="com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor"/>  
12            <interceptor name="fileUpload"class="org.apache.struts2.interceptor.FileUploadInterceptor"/>  
13            <interceptor name="i18n"class="com.opensymphony.xwork2.interceptor.I18nInterceptor"/>  
14            <interceptor name="logger"class="com.opensymphony.xwork2.interceptor.LoggingInterceptor"/>  
15            <interceptor name="modelDriven"class="com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor"/>  
16            <interceptor name="scopedModelDriven"class="com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor"/>  
17            <interceptor name="params"class="com.opensymphony.xwork2.interceptor.ParametersInterceptor"/>  
18            <interceptor name="actionMappingParams"class="org.apache.struts2.interceptor.ActionMappingParametersInteceptor"/>  
19            <interceptor name="prepare"class="com.opensymphony.xwork2.interceptor.PrepareInterceptor"/>  
20            <interceptor name="staticParams"class="com.opensymphony.xwork2.interceptor.StaticParametersInterceptor"/>  
21            <interceptor name="scope"class="org.apache.struts2.interceptor.ScopeInterceptor"/>  
22            <interceptor name="servletConfig"class="org.apache.struts2.interceptor.ServletConfigInterceptor"/>  
23            <interceptor name="sessionAutowiring"class="org.apache.struts2.spring.interceptor.SessionContextAutowiringInterceptor"/>  
24            <interceptor name="timer"class="com.opensymphony.xwork2.interceptor.TimerInterceptor"/>  
25            <interceptor name="token"class="org.apache.struts2.interceptor.TokenInterceptor"/>  
26            <interceptor name="tokenSession"class="org.apache.struts2.interceptor.TokenSessionStoreInterceptor"/>  
27            <interceptor name="validation"class="org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor"/>  
28            <interceptor name="workflow"class="com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor"/>  
29            <interceptor name="store"class="org.apache.struts2.interceptor.MessageStoreInterceptor"/>  
30            <interceptor name="checkbox"class="org.apache.struts2.interceptor.CheckboxInterceptor"/>  
31            <interceptor name="profiling"class="org.apache.struts2.interceptor.ProfilingActivationInterceptor"/>  
32            <interceptor name="roles"class="org.apache.struts2.interceptor.RolesInterceptor"/>  
33            <interceptor name="jsonValidation"class="org.apache.struts2.interceptor.validation.JSONValidationInterceptor"/>  
34            <interceptornameinterceptorname="annotationWorkflow"class="com.opensymphony.xwork2.interceptor.annotations.AnnotationWorkflowInterceptor"/>  

对于sturts2自带的拦截器,使用起来就相对比较方便了,我们只需要在struts.xml的action标签中加入<interceptor-ref name=" logger " />并且struts.xml扩展struts-default,就可以使用,

   如果是要自定义拦截器,首先需要写一个拦截器的类:

 1 package ceshi;  
 2 import com.opensymphony.xwork2.ActionInvocation;  
 3 import com.opensymphony.xwork2.interceptor.AbstractInterceptor;  
 4    
 5 publicclassAuthorizationInterceptor extends AbstractInterceptor {  
 6    
 7     @Override  
 8     public Stringintercept(ActionInvocation ai)throws Exception {  
 9          
10            System.out.println("abc");  
11             return ai.invoke();  
12              
13     }  
14    
15 }  

并且在struts.xml中进行配置

 1 <!DOCTYPEstruts PUBLIC  
 2 "-//Apache SoftwareFoundation//DTD Struts Configuration 2.0//EN"  
 3 "http://struts.apache.org/dtds/struts-2.0.dtd">  
 4    
 5    
 6 <struts>  
 7     <package name="test"extends="struts-default">  
 8      <interceptors>  
 9       <interceptor name="abc"class ="ceshi.AuthorizationInterceptor"/>  
10     </interceptors>  
11         <action name="TestLogger"class="vaannila.TestLoggerAction">  
12            <interceptor-refnameinterceptor-refname="abc"/>  
13            <result name="success">/success.jsp</result>  
14            </action>  
15     </package>  
16 </struts> 

8、一旦Action执行完毕,ActionInvocation负责根据struts.xml中的配置找到对应的返回结果。返回结果通常是(但不总是,也可能是另外的一个Action链)一个需要被表示的JSP或者FreeMarker的模版。在表示的过程中可以使用Struts2 框架中继承的标签。在这个过程中需要涉及到ActionMapper

 

在上述过程中所有的对象(Action,Results,Interceptors,等)都是通过ObjectFactory来创建的。

 

Struts2和struts1的比较

    struts2相对于struts1来说简单了很多,并且功能强大了很多,我们可以从几个方面来看:

    从体系结构来看:struts2大量使用拦截器来出来请求,从而允许与业务逻辑控制器 与 servlet-api分离,避免了侵入性;而struts1.x在action中明显的侵入了servlet-api.

    从线程安全分析:struts2.x是线程安全的,每一个对象产生一个实例,避免了线程安全问题;而struts1.x在action中属于单线程。

    性能方面:struts2.x测试可以脱离web容器,而struts1.x依赖servlet-api,测试需要依赖web容器。

    请求参数封装对比:struts2.x使用ModelDriven模式,这样我们 直接 封装model对象,无需要继承任何struts2的基类,避免了侵入性。

    标签的优势:标签库几乎可以完全替代JSTL的标签库,并且 struts2.x支持强大的ognl表达式。

    当然,struts2和struts1相比,在 文件上传,数据校验 等方面也 方便了好多。在这就不详谈了。

    

    一个比较优秀的框架可以帮着我们更高效,稳定的开发合格的产品,不过我们也不要依赖框架,我们只要理解了思想,设计模式,我们可以自己扩展功能,不然 就要 永远让别人牵着走了!

二、Struts2简单入门实例和登录实例

 

Java Struts2简单入门实例和登录实例

  1 jsp出发action
  2 struts2拦截请求,调用后台action
  3 action返回结果,由不同的jsp展现数据

项目结构

src
      struts.xml
      
   com
       hellostruts2
           action
                  HelloStrutsAction.java
                  LoginAction.java
                  
           model
                   HelloMessage.java
                   
WebContent
       HelloStruts.jsp
       index.jsp
       
    login
           error.jsp
           login.jsp
           success.jsp
           
    WEB-INF
           web.xml
           
        classes
               logging.properties
               mess.properties
               mess_zh_CN.properties
               
        lib
                commons-fileupload-1.3.1.jar
                commons-io-2.2.jar
                commons-lang-2.4.jar
                commons-lang3-3.2.jar
                commons-logging-1.1.3.jar
                freemarker-2.3.22.jar
                javassist-3.11.0.GA.jar
                ognl-3.0.14.jar
                struts2-core-2.3.28.1.jar
                xwork-core-2.3.28.1.jar

Web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xmlns="http://java.sun.com/xml/ns/javaee" 
   xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
   xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
   http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
   id="WebApp_ID" version="3.0">
   
   <display-name>Struts 2</display-name>
   <welcome-file-list>
      <welcome-file>index.jsp</welcome-file>
   </welcome-file-list>
   <filter>
      <filter-name>struts2CleanupFilter</filter-name>
      <filter-class>org.apache.struts2.dispatcher.ActionContextCleanUp</filter-class>
   </filter>
   <filter>
      <filter-name>struts2Filter</filter-name>
      <filter-class>org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class>
   </filter>

    <filter-mapping>
      <filter-name>struts2CleanupFilter</filter-name>
      <url-pattern>/*</url-pattern>
      <dispatcher>REQUEST</dispatcher>
      <dispatcher>FORWARD</dispatcher>
   </filter-mapping>
   <filter-mapping>
      <filter-name>struts2Filter</filter-name>
      <url-pattern>/*</url-pattern>
   </filter-mapping>
</web-app>

Struts.xml

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <!DOCTYPE struts PUBLIC
 3    "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
 4    "http://struts.apache.org/dtds/struts-2.0.dtd">
 5 <struts>
 6     <constant name="struts.devMode" value="true" />
 7     
 8     <constant name="struts.custom.i18n.resources" value="mess"/>
 9     <constant name="struts.i18n.encoding" value="utf-8"/>
10     
11     
12     <package name="hellostruts" extends="struts-default">
13         <action name="index">
14             <result >/index.jsp</result>
15         </action>
16         <action name="hello" class="com.hellostruts2.action.HelloStrutsAction" method="execute">
17             <result name="success">/HelloStruts.jsp</result>
18         </action>
19     </package>
20     <package name="loginstruts" extends="struts-default">
21         <action name="login" class="com.hellostruts2.action.LoginAction" method="execute">
22             <result name="input">/login/login.jsp</result>
23             <result name="success">/login/success.jsp</result>
24             <result name="error">/login/error.jsp</result>
25         </action>
26     </package>
27     
28 </struts>
29 <!-- 
30 <struts>
31     <include file="my-struts1.xml"/>
32     <include file="my-struts2.xml"/>
33 </struts>
34 -->

logging.properties

org.apache.catalina.core.ContainerBase.[Catalina].level = INFO
org.apache.catalina.core.ContainerBase.[Catalina].handlers = \java.util.logging.ConsoleHandler

mess.properties

loginPage=loginPage
errorPage=errorPage
successPage=succPage
errorTip=sorry\uFF0C login failed
successTip=welcome{0},login success
user=username
pass=password
login=login

mess_zh_CN.properties

loginPage=登陆界面
errorPage=失败界面
successPage=成功界面
errorTip=对不起,您不能登录!
successTip=欢迎,{0},您已经登录!
user=用户名
pass=密 码
login=登陆

入门实例:

HelloMessage.java

 1 package com.hellostruts2.model;
 2 
 3 public class HelloMessage {
 4     private String message;
 5     public HelloMessage(){
 6         setMessage("Hello struts2 model.");
 7     }
 8     public String getMessage() {
 9         return message;
10     }
11 
12     public void setMessage(String message) {
13         this.message = message;
14     }
15 }

HelloStrutsAction.java

 1 package com.hellostruts2.action;
 2 
 3 import com.hellostruts2.model.HelloMessage;
 4 
 5 public class HelloStrutsAction {
 6 
 7     private String name;
 8     private HelloMessage helloMessage;
 9     public String execute() throws Exception{
10         helloMessage=new HelloMessage();
11         helloMessage.setMessage("Hello struts model.");
12         return "success";
13     }
14     public String getName(){
15         return name;
16     }
17     public void setName(String name){
18         this.name=name;
19     }
20     
21     public HelloMessage getMessage(){
22         return helloMessage;
23     }
24     public void setMessage(HelloMessage helloMessage){
25         this.helloMessage=helloMessage;
26     }
27 }

index.jsp

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<%@ taglib prefix="s" uri="/struts-tags"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Hello Struts2 Form</title>
</head>
<body>
    <h1>Hello Struts2 Form</h1>
    <form action="hello">
        <label for="name">Please enter your name</label><br/>
        <input type="text" name="name"/>
        <input type="submit" value="Say Hello"/>
        <p><a href="<s:url action=‘hello‘/>">Hello Struts Model</a></p>
    </form>
</body>
</html>

HelloStruts.jsp

 1 <%@ page language="java" contentType="text/html; charset=ISO-8859-1"
 2     pageEncoding="ISO-8859-1"%>
 3 <%@ taglib prefix="s" uri="/struts-tags" %>
 4 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
 5 <html>
 6 <head>
 7 <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
 8 <title>Hello Struts2</title>
 9 </head>
10 <body>
11 <s:debug></s:debug>
12     Hello Struts2, <s:property value="name"/>
13     <br/>
14     Hello Model, <s:property value="message.message"></s:property>
15     ${message.message}
16 </body>
17 </html>

登录实例:

当login.jsp触发action时,就会向后抬发送login.action的请求,这个请求被后台拦截,交给struts.xml中配置的action处理。

LoginAction.java

 1 package com.hellostruts2.action;
 2 
 3 import com.opensymphony.xwork2.ActionContext;
 4 import com.opensymphony.xwork2.ActionSupport;
 5 
 6 public class LoginAction extends ActionSupport {
 7     private static final long serialVersionUID = 1L;
 8     private String username;
 9     private String password;
10     public String getUsername() {
11         return username;
12     }
13     public void setUsername(String username) {
14         this.username = username;
15     }
16     public String getPassword() {
17         return password;
18     }
19     public void setPassword(String password) {
20         this.password = password;
21     }
22     public String execute() throws Exception{
23         if(getUsername().equals("test") && getPassword().equals("test")){
24             ActionContext.getContext().getSession().put("user", getUsername());
25             return SUCCESS;
26         }else{
27             return ERROR;
28         }
29     }
30     public void validate(){
31         if(username ==null || username.trim().equals("")){
32             addFieldError("username", "user name is required");
33         }
34         if(password.length()<3){
35             addFieldError("password", "password must be more than 3");
36         }
37     }
38 }

login.jsp

 1 <%@ page language="java" contentType="text/html; charset=UTF-8"
 2     pageEncoding="UTF-8"%>
 3 <%@taglib prefix="s" uri="/struts-tags" %>
 4 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
 5 <html>
 6 <head>
 7 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
 8 <title><s:text name="loginPage"/></title>
 9 </head>
10 <body>
11 <s:form action="login">
12     <s:textfield name="username" key="user"></s:textfield>
13     <s:textfield name="password" key="pass"></s:textfield>
14     <s:submit key="login"></s:submit>
15 </s:form>
16 </body>
17 </html>

success.jsp

 1 <%@ page language="java" contentType="text/html; charset=utf-8"
 2     pageEncoding="utf-8"%>
 3 <%@taglib prefix="s" uri="/struts-tags" %>
 4 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
 5 <html>
 6 <head>
 7 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
 8 <title><s:text name="successPage"></s:text></title>
 9 </head>
10 <body>
11     <s:text name="successTip">
12         <s:param>${sessionScope.user}</s:param>
13     </s:text>
14 </body>
15 </html>

error.jsp

 1 <%@ page language="java" contentType="text/html; charset=utf-8"
 2     pageEncoding="utf-8"%>
 3 <%@taglib prefix="s" uri="/struts-tags" %>
 4 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
 5 <html>
 6 <head>
 7 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
 8 <title><s:text name="errorPage"></s:text></title>
 9 </head>
10 <body>
11     <s:text name="errorTip"></s:text>
12 </body>
13 </html>

library下载:http://struts.apache.org/download.cgi

Struts2原理及简单实例