struts中的error问题！

Question

//------------------LogonForm-----------------package addressbook.forms;import javax.servlet.http.HttpServletRequest;
import org.apache.struts.action.ActionMessage;
import org.apache.struts.action.ActionErrors;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionMapping;
/**
 * <strong>LogonForm</strong> handles the form
 * that the user will use to logon to the application.
 */public final class LogonForm extends ActionForm {
    private String username = null;
    private String password = null;
    public String getUserName() {
return (this.username);
    }    public void setUserName(String username) {
        this.username = username;
    }
    public String getPassword() {
return (this.password);
    }    public void setPassword(String password) {
        this.password = password;
    }    public void reset(ActionMapping mapping, HttpServletRequest request) {
        this.username = null;
        this.password = null;    }    public ActionErrors validate(ActionMapping mapping,
                                 HttpServletRequest request) {        ActionErrors errors = new ActionErrors();
        if ((username == null) || (username.length() < 1))
            //errors.add("username", new ActionMessage("error.username.required"));
            {
             errors.add("username", new ActionMessage("com.jeffaple.struts"));
             System.out.println("username can not be null!!");
            }
        if ((password == null) || (password.length() < 1))
            errors.add("password", new ActionMessage("error.password.required"));        return errors;    }
}//---------------logon.jsp-----------------
<%@ include file="taglibs.jsp" %>
<%@ include file="header.jsp" %>
<%@ include file="logonContent.jsp" %>
<%@ include file="footer.jsp" %>//---------------logonContent.jsp------------
<%@ include file="taglibs.jsp" %><html:errors/>
<html:form action="/logon.do" focus="userName" >
<center>
<table border="0" width="100%">  <tr>
    <th align="right">
      <bean:message key="prompt.username"/>
    </th>
    <td align="left">
      <html:text property="userName" size="15" maxlength="15"/>
    </td>
  </tr>  <tr>
    <th align="right">
      <bean:message key="prompt.password"/>
    </th>
    <td align="left">
      <html:password property="password" size="15" maxlength="15"
                    redisplay="false"/>
    </td>
  </tr>  <tr>
    <td align="right">
    <html:submit property="submit" >                     
<bean:message key="button.logon"/>
</html:submit>    </td>
    <td align="left">
    <html:reset >                     
<bean:message key="button.reset"/>
</html:reset>    </td>
  </tr></table>
</center>
</html:form>

Answer 1

//---------------------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>
<!-- ============ Data Source =================================== -->  <!-- ========== Form Bean Definitions =================================== -->
  <form-beans>
    <form-bean      name="logonForm"
                    type="addressbook.forms.LogonForm"/>
    <form-bean      name="searchForm"
                    type="addressbook.forms.SearchForm"/>                    
    <form-bean      name="insertForm"
                    type="addressbook.forms.InsertForm"/>
   
  </form-beans> 
  <!-- ========== Global Forward Definitions ============================== -->
  <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 Mapping Definitions ============================== -->
    <action-mappings>
   <action    path="/search"
              type="addressbook.actions.SearchAction"
              name="searchForm"
              attribute="myForm"
              scope="request"
              input="/search.jsp">
      <forward name="success" path="/display.jsp"/>
    </action>
    <action    path="/displayall"
               type="addressbook.actions.DisplayAllAction"
               name="nestedForm"
               scope="request"
               input="/mainMenu.jsp">
      <forward name="success" path="/display.jsp"/>
    </action>
    
  
    <action   path="/insert"
              type="addressbook.actions.InsertAction"
              name="insertForm"
              scope="request"
              input="/insert.jsp"
              validate="true">
 
    </action>
    
    <!-- Process a user logoff -->
    <action    path="/logoff"
               type="addressbook.actions.LogoffAction">
      <forward name="success" path="/index.jsp"/>
    </action>    <!-- Process a user logon -->
    <action    path="/logon"
               type="addressbook.actions.LogonAction"
               name="logonForm"
              scope="request"
              input="/logon.jsp">
    </action>
    </action-mappings>
 
  <message-resources parameter="addressbook.ApplicationResources"/></struts-config>//-----------------LogonAction.java--------------------------
package addressbook.actions;
import java.io.IOException;
import java.util.Hashtable;
import java.util.Locale;
import java.util.Properties;
import java.util.ResourceBundle;
import java.util.MissingResourceException;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpServletResponse;
import org.apache.struts.action.Action;
import org.apache.struts.action.ActionMessage;
import org.apache.struts.action.ActionMessages;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.action.ActionServlet;
import org.apache.struts.util.MessageResources;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;import addressbook.Constants;
import addressbook.model.UserBean;
import addressbook.forms.LogonForm;/**
 * <strong>LogonAction</strong> provides the login mechanism
 * for the sample application. The username/password pair that
 * is entered by the user will be compared against the database
 * values that where read in at application startup. An error will
 * be reported if the username/password don't match, otherwise
 * a <code>User</code> Object will be inserted into the session
 * to indicate that the user is currently logged in.
 */
public final class LogonAction extends AbstActionBase {
private Log log =
        LogFactory.getLog(this.getClass().getName());
public ActionForward execute(ActionMapping mapping,
 ActionForm form,
 HttpServletRequest request,
 HttpServletResponse response)
throws Exception { String userName=null;
String password=null;
Locale locale = getLocale(request);
MessageResources messages = getResources(request); UserBean user = null;
// Demonstrate a trace call to the logger
if (log.isTraceEnabled()) {
log.trace("LogonAction: entering method");
}
// Validate the request parameters specified by the user
ActionMessages errors = new ActionMessages();
if (form != null){
  userName = ((LogonForm) form).getUserName();
  password = ((LogonForm) form).getPassword();
}
Hashtable database = (Hashtable)
  servlet.getServletContext().getAttribute(Constants.DATABASE_KEY);
if (database == null)
            errors.add(ActionMessages.GLOBAL_MESSAGE,
                       new ActionMessage("error.database.missing"));
else {
    user = (UserBean) database.get(userName);
    if ((user != null) && !user.getPassword().equals(password)){
user = null;
}
    if (user == null)
                errors.add(ActionMessages.GLOBAL_MESSAGE,
                           new ActionMessage("error.password.mismatch"));
} // Report any errors we have discovered back to the original form
if (!errors.isEmpty()) {
    saveErrors(request, errors);
    return (new ActionForward(mapping.getInput()));
}
// Save our logged-in user in the session
HttpSession session = request.getSession();
session.setAttribute(Constants.USER_KEY, user);
// Demonstrate a debug call to the logger
if (log.isDebugEnabled()) {
log.debug("LogonAction: User '" + user.getUserName() +
       "' logged on in session " + session.getId());
}
        // Remove the obsolete form bean
if (mapping.getAttribute() != null) {
            if ("request".equals(mapping.getScope()))
                request.removeAttribute(mapping.getAttribute());
            else
                session.removeAttribute(mapping.getAttribute());
        } // Forward control to the specified success URI
return (mapping.findForward(Constants.FORWARD_SUCCESS));    }}

Answer 2

<html:errors/>
显示所有的错误信息.
如果要一条一条显示,用
<html:errors property=""/>

Answer 3

<html:errors/>默认的是显示request或session范围内的所有ActionMessages或ActionErrors对象内容，<html:errors property="aa"/>只显示名为aa的对象

Answer 4

to rickhunterchen(千山鸟飞绝):
显示所有的错误信息.？那是什么时候把error.header和error.footer加进去的呢？
在form里面 validate时候，只有 errors.add("username", new ActionMessage("error.username.required"));？

Answer 5

那是不是在哪里先add进去一些ActionMessage了呢？

Answer 6

error.header和error.footer
是自动加进去的
每一个显示error的地方都会包含这个。主要用来做error的特殊显示。

Answer 7

Struts+Spring+Hibernate　ＱＱ群：9967568

Answer 8

>偶就是想知道，在哪里加进去的?是在 Struts 的 <html:errors 标签的具体实现中加进去的。如果楼主有兴趣，可以下一份源代码看看，写得极复杂，看半天或许只能看出个大概。