Получение исключения при использовании платформы валидатора в структурах

Question

Невозможно выполнить проверки для страницы входа в систему с помощью Struts.Здесь я храню данные для входа, введенные пользователем в базу данных.Я не хочу хранить нулевые значения в базе данных.Но в следующей программе, если я отправляю форму без ввода данных, она дает исключение .. проверки не генерируются .. Пожалуйста, предложите мне.Здесь я публикую свои программы.

Заранее спасибо

LoginFormBean.java
------------

 package info.strutspkg;

    import javax.servlet.http.HttpServletRequest;

    import org.apache.struts.action.ActionErrors;
    import org.apache.struts.action.ActionForm;
    import org.apache.struts.action.ActionMapping;
    import org.apache.struts.action.ActionMessage;
    import org.apache.struts.validator.DynaValidatorForm;

    public class LoginFormBean extends DynaValidatorForm 
    {

        private String username;
        private String password;

        public void setUsername(String username) {
            this.username = username;
        }

        public String getUsername() {
            return username;
        }

        public void setPassword(String password) {
            this.password = password;
        }

        public String getPassword() {
            return password;
        }
    }

LoginActionClass.java
------------

package info.strutspkg;

import java.sql.Connection;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import login.logindao.Logindao;

import org.apache.struts.action.*;
import org.apache.struts.validator.DynaValidatorForm;

public class LoginActionClass extends Action{

     public ActionForward execute(ActionMapping mapping,ActionForm form,HttpServletRequest request,HttpServletResponse response)throws Exception
     {
         Connection con=null;
            String key=null;
    try{

      DynaValidatorForm loginForm=(DynaValidatorForm)form;
      String uname=loginForm.get("username").toString();
      String pwd=loginForm.getString("password").toString();


      Logindao dao=new Logindao();

      int i=dao.insert(uname,pwd);

      System.out.println("r value returned"); 
      if(i>0){
        key="success";
       }
       else
       {
        key="failure";
       }
      }
      catch(Exception e){
       e.printStackTrace();
       System.out.println("Error occured");

       }
    return mapping.findForward(key);
    }
    }

Logindao.java
    --------

    package login.logindao;

    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.PreparedStatement;
    import java.sql.SQLException;

    public class Logindao {

        public int insert(String uname,String pwd){
              int r=0;
              PreparedStatement ps = null;
              Connection conn=null;

              String url = "jdbc:sqlserver://localhost:1433;DatabaseName=sample;user=sa;password=lalitha";

                     try
                        {
                            Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
                            //Get a connection
                         conn = DriverManager.getConnection(url); 
                        }
                        catch (Exception except)
                        {
                            except.printStackTrace();
                        }
              //get connection object from DBConnection class
              System.out.println("Connection"+conn);

              try{
               //use PreparedStatement to insert the values of username and password
               ps=conn.prepareStatement("insert into login(username,password) values(?,?)");
               ps.setString(1, uname);
               ps.setString(2, pwd);
               r = ps.executeUpdate();
              }
              catch(SQLException ex) {
               try {
                ps.close();
                conn.close();
               } catch (SQLException e) {
                e.printStackTrace();
               }
               System.err.println("SQLException: " + ex.getMessage());
              }
              System.out.println("r="+r);
              return r;

             }

    }



 ApplicationResources.properties
    -----------
    logindetails.username= username
    logindetails.password= password



struts-config.xml
    --------
    <form-beans>
      <form-bean name="logindetails" type="org.apache.struts.validator.DynaValidatorForm">
      <form-property name="username" type="java.lang.String"></form-property>
      <form-property name="password" type="java.lang.String"></form-property>
      </form-bean>
      </form-beans>
    <action path="/register" name="logindetails" type="info.strutspkg.LoginActionClass" scope="request" validate="true">
      <forward name="success" path="/success.jsp"/>
      <forward name="failure" path="/failure.jsp"/>
      </action>
      </action-mappings>


      <message-resources parameter="info.strutspkg.ApplicationResources" />

       <!--  Validator plugin -->

      <plug-in className="org.apache.struts.validator.ValidatorPlugIn">
      <set-property property="pathnames"  value="/WEB-INF/validator-rules.xml,/WEB-INF/validation.xml"/>
      </plug-in> 

validation.xml

      <form name="logindetails">

        <field
            property="username"
            depends="required">
                <arg key="logindetails.username"/>
        </field>
        <field
            property="password"
            depends="required">
                <arg key="logindetails.password"/>
        </field>

    </form>

</formset>



Error:
------
HTTP Status 500 - 

--------------------------------------------------------------------------------

type Exception report

message 

description The server encountered an internal error () that prevented it from fulfilling this request.

exception 

javax.servlet.ServletException: The path of an ForwardConfig cannot be null
    org.apache.struts.chain.ComposableRequestProcessor.process(ComposableRequestProcessor.java:286)
    org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)
    org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:462)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:810)
    org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:81)


root cause 

java.lang.IllegalArgumentException: The path of an ForwardConfig cannot be null
    org.apache.struts.chain.commands.servlet.PerformForward.perform(PerformForward.java:70)
    org.apache.struts.chain.commands.AbstractPerformForward.execute(AbstractPerformForward.java:54)
    org.apache.struts.chain.commands.ActionCommandBase.execute(ActionCommandBase.java:51)
    org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:190)
    org.apache.commons.chain.generic.LookupCommand.execute(LookupCommand.java:304)
    org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:190)
    org.apache.struts.chain.ComposableRequestProcessor.process(ComposableRequestProcessor.java:283)
    org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)
    org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:462)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:810)
    org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:81)