一个struts程序运行的流程问题！

Question

小弟我刚开始学习struts，版本是1.1 我想问一下，表单数据提交后，先在WEB.XML里面找ACTION 的mapping然后去struts-config.xml里面找相应的<action name>找到formbean，如果我的formbean第一次基本的表单验证失败，比如：输入为空，现在把errors返回给request，之后就会通过struts-config.xml中的<action input>属性返回给页面，我想知道以上流程是对的吗？如果是对的，那就是说不需要经过Action罗？不知道我理解的对不对，请高手大哥大姐们指点一下小弟，万分感谢！

Answer 1

没用过formbean验证过数据,一般用JS,
struts好象有个专门的验证机制,不用经过action

Answer 2

 看看图片吧，我从别的地方贴过来的。你的formbean是只什么地方的formbean?普通的bean?还是ActionForm？如果你在ActionForm里面验证然后就转了的话，你的说法是成立的。但是如果你的bean是在Action里面实例话然后执行execute以后又转的，这样就执行Action了。尽量不要在ActionFrom里面写业务逻辑。

Answer 3

如果是采用frombean验证的话，当验证失败的时候，确实是不会走到Action里面的

Answer 4

哦，回答2楼的大哥，我的formbean的确是ActionForm。我刚开始看书自学，书上说，验证表单输出的是否为空，这样的验证不算是业务逻辑吧？

Answer 5

其实上面那个图形你看看就了解了，在1.1中 ，你页面请求的化是先找到strut-config.xml中你要请求的action.如果action中你指定了name,那么就调用相应的form，当form中验证失败直接通过actionerrors返回错误，而不会再去调用action.

Answer 6

LongonContent.jsp:<%@ include file="taglibs.jsp" %><br>
<html:errors/>
<br>
<center>
<html:form action="logon.do" focus="userName">
<table>
<tr>
<td align="right">
<bean:message key="prompt.username"/>
</td>
<td align="right">
<html:text property="userName" size="15" maxlength="15"/>
</td>
</tr>
<tr>
<td align="right">
<bean:message key="prompt.password"/>
</td>
<td align="right">
<html:password property="password" size="15" maxlength="15"/>
</td>
</tr>

<tr>
<td align="center">
<html:submit property="submit">
<bean:message key="button.logon"/>
</html:submit>
</td>
<td align="center">
<html:reset>
<bean:message key="button.reset"/>
</html:reset>
</td>
</tr>
</table>
</html:form>
</center>
FormAction:
import javax.servlet.http.HttpServletRequest;
import org.apache.struts.action.*;public final class HelloForm extends ActionForm{

private String userName = null;

public String getUserName(){
return (this.userName);
}

public void setUserName(String userName){
this.userName =userName;
}

public void reset(ActionMapping mapping,HttpServletRequest request){
this.userName = null;
}

public ActionErrors validate(ActionMapping mapping,HttpServletRequest request){

ActionErrors errors  = new ActionErrors();

if((userName == null)||(userName.length()<1))
errors.add("userName",new ActionMessage("hello.no.username.error"));

return errors;
}

}WEB.xml:
<?xml version="1.0" encoding="UTF-8"?>
<web-app>
  <display-name>Struts AddressBook Sample Applications</display-name>
    <servlet>
    <servlet-name>action</servlet-name>
    <servlet-class>org.apache.struts.action.ActionServlet</servlet-class>
    <init-param>
      <param-name>config</param-name>
      <param-value>/WEB-INF/struts-config.xml</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
  </servlet>
  
  <servlet-mapping>
    <servlet-name>action</servlet-name>
    <url-pattern>*.do</url-pattern>
  </servlet-mapping>
  
  
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
  
  
    
  <taglib>
    <taglib-uri>/WEB-INF/struts-bean.tld</taglib-uri>
    <taglib-location>/WEB-INF/tld/struts-bean.tld</taglib-location>
  </taglib>
  
  <taglib>
    <taglib-uri>/WEB-INF/struts-html.tld</taglib-uri>
    <taglib-location>/WEB-INF/tld/struts-html.tld</taglib-location>
  </taglib>
  
  <taglib>
    <taglib-uri>/WEB-INF/struts-logic.tld</taglib-uri>
    <taglib-location>/WEB-INF/tld/struts-logic.tld</taglib-location>
  </taglib>
  
  
</web-app>struts-config.xml:
<?xml version="1.0" encoding="ISO-8859-1" ?><!DOCTYPE struts-config PUBLIC
          "-//Apache Software Foundation//DTD Struts Configuration 1.1//EN"
          "http://jakarta.apache.org/struts/dtds/struts-config_1_1.dtd">
       
<struts-config>  <form-beans>
    <form-bean      name="logonForm"     type="forms.LogonForm"/>
    
    <form-bean      name="searchForm"    type="forms.SearchForm"/>   
                     
    <form-bean      name="insertForm"    type="forms.InsertForm"/>
   
  </form-beans>  <global-forwards>
    <forward   name="logoff"               path="/logoff.do"/>
    <forward   name="logon"                path="/logon.jsp"/>
    <forward   name="success"              path="/mainMenu.jsp"/>
    <forward   name="search"               path="/search.jsp"/>
    <forward   name="displayall"           path="/displayall.do"/>
    <forward   name="insert"               path="/insert.jsp"/>
    <forward   name="mainMenu"             path="/mainMenu.jsp"/>
    <forward   name="confirmation"        path="/confirmation.jsp"/>
  </global-forwards>    <action-mappings>
    <action     path="/search"
              type="actions.SearchAction"
               name="searchForm"
               attribute="myForm"
               scope="request"
               input="/search.jsp">
       <forward name="success" path="/display.jsp"/>
     </action>
     <action    path="/displayall"
               type="actions.DisplayAllAction"
               name="nestedForm"
               scope="request"
               input="/mainMenu.jsp">
       <forward name="success" path="/display.jsp"/>
     </action>
    
  
     <action   path="/insert"
              type="actions.InsertAction"
              name="insertForm"
              scope="request"
              input="/insert.jsp"
              validate="true">
 
     </action>
    
    
    
     <action    path="/logoff"
               type="actions.LogoffAction">
       <forward name="success" path="/index.jsp"/>
     </action>    
    
     <action    path="/logon"
               type="actions.LogonAction"
               name="logonForm"
               scope="request"
               validate="true"
               input="/logonContent.jsp">
              
       <forward name="success" path="/mainMenu.jsp"/>
     </action>
    </action-mappings>
 
  <message-resources parameter="ApplicationResources"/></struts-config>按照上面的程序，进入logonContent.jsp后如果不在输入框里面输入，直接点Submit，按理说应该弹出errors提示啊。结果网页报错:
HTTP Status 500 - 
type Exception reportmessage description The server encountered an internal error () that prevented it from fulfilling this request.
exception 
org.apache.jasper.JasperException
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:372)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.apache.struts.action.RequestProcessor.doForward(RequestProcessor.java:1069)
org.apache.struts.action.RequestProcessor.internalModuleRelativeForward(RequestProcessor.java:1012)
org.apache.struts.action.RequestProcessor.processValidate(RequestProcessor.java:980)
org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:255)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1482)
org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:525)
javax.servlet.http.HttpServlet.service(HttpServlet.java:709)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
root cause 
java.lang.ClassCastException
org.apache.struts.taglib.html.ErrorsTag.doStartTag(ErrorsTag.java:215)
org.apache.jsp.logonContent_jsp._jspx_meth_html_errors_0(logonContent_jsp.java:119)
org.apache.jsp.logonContent_jsp._jspService(logonContent_jsp.java:90)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:94)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:324)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.apache.struts.action.RequestProcessor.doForward(RequestProcessor.java:1069)
org.apache.struts.action.RequestProcessor.internalModuleRelativeForward(RequestProcessor.java:1012)
org.apache.struts.action.RequestProcessor.processValidate(RequestProcessor.java:980)
org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:255)


note The full stack trace of the root cause is available in the Apache Tomcat/5.0.30 logs.
Apache Tomcat/5.0.30

Answer 7

没有仔细看,不过这里的HelloForm可以是final的吗?还有formbean中的验证属于客户端的验证.
public final class HelloForm extends ActionForm

Answer 8

可以啊，我前面的一个例子就用的final，没有问题

Answer 9

你把验证都放到Action里吧。这样写有点问题在Action 中的execute中处理业务