在'com.home.homeapp.actionform.LoginForm'类型的bean中找不到有关属性'userName'的任何信息

时间：2011-06-01 03:19:34

标签： java mysql eclipse ide jboss

我正在为我的应用程序使用Eclipse Java EE IDE，JBOSS v5.0，java版本1.5.0_16和MySQL v5.1.0。我正在尝试使用Bean和Servlet在JSP中对应用程序进行身份验证。

我的步骤：

步骤：1创建一个网页“login.jsp”以登录用户。

<html>
<head>
</head>
<body>
<form name="loginform" method="post" action="loginbean.jsp">
<br><br>
<table align="center"><tr><td><h2>Login Authentication</h2></td></tr></table>
<table width="300px" align="center" style="border:1px solid #000000;background-color:#efefef;">
<tr><td colspan=2></td></tr>
<tr><td colspan=2> </td></tr>
  <tr>
  <td><b>Login Name</b></td>
  <td><input type="text" name="userName" value=""></td>
  </tr>
  <tr>
  <td><b>Password</b></td>
  <td><input type="password" name="password" value=""></td>
  </tr>
  <tr>
  <td></td>
  <td><input type="submit" name="Submit" value="Submit"></td>
  </tr>
  <tr><td colspan=2> </td></tr>
</table>
</form>
</body>
</html>

步骤：2创建“loginbean.jsp”以设置登录参数。

<%@ page language="Java" import="java.sql.*" %>  
<HTML> 
<HEAD><TITLE>DataBase Search</TITLE></HEAD>  
<BODY>
<jsp:useBean id="db" scope="request" class="logbean.LoginBean" >
  <jsp:setProperty name="db" property="userName" value="<%=request.getParameter("userName")%>"/>
  <jsp:setProperty name="db" property="password" value="<%=request.getParameter("password")%>"/>
 </jsp:useBean>
<jsp:forward page="hello">
  <jsp:param name="username" value="<%=db.getUserName()%>" />
  <jsp:param name="password" value="<%=db.getPassword()%>" />
</jsp:forward> 
</body>
</html>

步骤：3创建“LoginBean.java”以映射“loginbean.jsp”参数。

package logbean;
public class LoginBean {
  String userName="";
  String password="";
  public String getUserName() {
  return userName;
  }
  public void setUserName(String userName) {
  this.userName = userName;
  }
  public String getPassword() {
  return password;
  }
  public void setPassword(String password) {
 this.password = password;
  }
  }

步骤：4创建一个Servlet“login.java”以验证用户登录。

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.sql.*;
import java.sql.*;
public class login extends HttpServlet{ 
 public void doPost(HttpServletRequest request, HttpServletResponse response)
   throws ServletException,IOException{
  response.setContentType("text/html");
  PrintWriter out = response.getWriter();
  System.out.println("MySQL Connect Example.");
  Connection conn = null;
  String url = "jdbc:mysql://localhost:3306/";
  String dbName = "user_register";
  String driver = "com.mysql.jdbc.Driver";
  String userName = "root"; 
  String password = "root";
 String username="";
 String userpass="";
 String strQuery= ""; 
  Statement st=null;
  ResultSet rs=null;
  HttpSession session = request.getSession(true);
  try {
  Class.forName(driver).newInstance();
  conn = DriverManager.getConnection(url+dbName,userName,password);
  if(request.getParameter("username")!=null &&
     request.getParameter("username")!="" && request.getParameter("password")!=null &&
     request.getParameter("password")!="")
  {
  username = request.getParameter("username").toString();
  userpass = request.getParameter("password").toString();
  strQuery="select * from userregister where 
    username='"+username+"' and  password='"+userpass+"'";
 System.out.println(strQuery);
  st = conn.createStatement();
  rs = st.executeQuery(strQuery);
  int count=0;
  while(rs.next())
  {
  session.setAttribute("username",rs.getString(2));
  count++;
  }
  if(count>0)
  {
  response.sendRedirect("welcome.jsp");
  }
  else
  {
 response.sendRedirect("login.jsp");
  }
  }
  else
  {
 response.sendRedirect("login.jsp");
  }
  System.out.println("Connected to the database"); 
  conn.close();
  System.out.println("Disconnected from database");
  } catch (Exception e) {
  e.printStackTrace();
  }
  }
}

步骤：5创建网页“welcome.jsp”以在成功消息后显示消息。

<HTML> 
<HEAD><TITLE>Welcome</TITLE></HEAD>  
<BODY>
<br><br><br><br>
<table align="center" style="border:1px solid #000000;">
<%
if(session.getAttribute("username")!=null && session.getAttribute("username")!="")
{
String user = session.getAttribute("username").toString();
%>
<tr><td align="center"><h1>Welcome <b><%= user%></b></h1></td></tr>
<%
}
%>
</table>
</body>
<html>

但是在错误发生之前运行应用程序：

type Exception report

message

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

exception

org.apache.jasper.JasperException: org.apache.jasper.JasperException: Cannot find any information on property 'userName' in a bean of type 'com.home.homeapp.actionform.LoginForm'
    org.apache.jasper.runtime.JspRuntimeLibrary.handleSetProperty(JspRuntimeLibrary.java:667)
    org.apache.jsp.loginbean_jsp._jspService(loginbean_jsp.java:66)
    org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:369)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:322)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:249)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)

root cause

org.apache.jasper.JasperException: Cannot find any information on property 'userName' in a bean of type 'com.home.homeapp.actionform.LoginForm'
    org.apache.jasper.runtime.JspRuntimeLibrary.getWriteMethod(JspRuntimeLibrary.java:795)
    org.apache.jasper.runtime.JspRuntimeLibrary.handleSetProperty(JspRuntimeLibrary.java:664)
    org.apache.jsp.loginbean_jsp._jspService(loginbean_jsp.java:66)
    org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:369)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:322)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:249)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)

注意JBoss Web / 2.1.3.GA日志中提供了根本原因的完整堆栈跟踪。

请帮助我。

此致 Bijoy

1 个答案:

答案 0 :(得分：1)

Cannot find any information on property 'userName' in a bean 
of type 'com.home.homeapp.actionform.LoginForm'

它看起来更像是JSP的问题。 Bean属性名称 以小写字母开头（除非你付出相当大的努力 否则）。最初的可能令人困惑 按惯例的小写字母在getter和setter中显示为大写 名称;例如，getEmpName()和setEmpName(String)就是 属性"empName"的getter和setter。

如果贾斯帕找不到豆类那么就会这样说;如果它 甚至检查某个特定财产的存在 已经内省了豆类。

如果您以大写形式创建属性并不重要，但我建议您必须确保该属性为小写。

public String getShipmentHeaderID() {
        return ShipmentHeaderID;
    }

    public void setShipmentHeaderID(String _ShipmentHeaderID) {
        ShipmentHeaderID = _ShipmentHeaderID;
    }

    public String getShipmentHeaderNumber() {
        return ShipmentHeaderNumber;
    }

    public void setShipmentHeaderNumber(String _ShipmentHeaderNumber) {
        ShipmentHeaderNumber = _ShipmentHeaderNumber;
    }


<td width="20%"><jsp:getProperty name="pBean" property="shipmentHeaderID" /></td>

<td width="20%"><jsp:getProperty name="pBean" property="shipmentHeaderNumber" /></td>
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