-- 作者：dorothyle
-- 发布时间：8/7/2011 6:27:00 PM
-- [求助]表单调用servlet，servlet调用jsp，调试通不过！
该工程实现用户登录界面。check.html提供用户输入用户帐号，如果输入错误，则重新输入，如果正确则显示帐户余额。现在的情况是如果帐号不正确，可以链接到指定的页面进行重新输入；如果帐户输入正确，则提示类属性值无效。整个工程包括四个文件： 1. check.html：表单调用servlet，并将用户输入的accountNo值传递给servlet； 2. GetAccount：这是一个servlet，接受表单的post请求，如果用户输入的帐号不正确，则调用check.html表单，提示用户重新输入帐号；如果用户输入的帐号正确，则调用showBalance.jsp，显示帐户姓名，以及余额。但这步总是提示： org.apache.jasper.JasperException: /showBalance.jsp(9,0) The value for the useBean class attribute chapter41.account is invalid.
3. 类account文件：我将这个类编绎以后的类文件放在Tomcat 6.0\webapps\root\WEB-INF\classes\文件夹下，将GetAccount的类文件也放置在上述目录下。
如果大家谁有时间，谁有条件，能否在自己的机器上配置一下，帮我看一下是哪里的问题？万分感谢！
check.html源代码:
<html>
<head><title>JSP+Servlet+JavaBean实例</title></head>
<h2>帐户查询</h2>
<h3>请输入帐户编号</h3>
<body>
<form action="servlet/chapter41.GetAccount" method="POST">
帐户编号：<input type="text" name="accountNo" size="20" maxlength="20"><br><br>
<input type="submit" name="submit" value="查询">
</form>
</body>
</html> GetAccount源代码：
package chapter41; import java.io.IOException;
import java.io.PrintWriter; import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse; public class GetAccount extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String accountNum = (String)request.getParameter("accountNo"); /*模拟数据库，通过姓名查找帐户信息对象*/
account oneAccount = (account)account.getAccountInfo(accountNum);
if (oneAccount == null){
/*如果找不到相应帐户信息，则创建该帐户信息*/
/*没有输入帐户号或帐号在数据库中不存在，则转入初始页面*/
response.sendRedirect("../check.html");
return;
}
/*把客户信息放在request请求对象中*/
request.setAttribute("account",oneAccount);
/*显示客户信息的jsp*/
response.sendRedirect("../showBalance.jsp"); } public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
this.doGet(request, response);
}
}
account类文件：
package chapter41;
import java.util.*; public class account{
protected String accountNum="";
protected String name="";
protected double balance=0; /*构造函数*/
public account(String accountNum, String name, double balance){
this.accountNum = accountNum;
this.name = name;
this.balance = balance;
}
/*模拟数据库建立几个帐户信息对象以供查找*/
protected static account firstAccount=new account("1110812006","dorothyle",3000.0);
protected static account secAccount=new account("86477456239","Michael",5000000.0);
protected static account trdAccount=new account("48961856232","John",66800.0);
/*通过帐号查找客户余额等信息*/
public static account getAccountInfo(String accountNum){
if (accountNum == null||accountNum.equals("")){
return null;
}else if (firstAccount.getAccountNum().equals(accountNum)){
return firstAccount;
}else if (secAccount.getAccountNum().equals(accountNum)){
return secAccount;
}else if (trdAccount.getAccountNum().equals(accountNum)){
return trdAccount;
}else{
return null;
}
}
/*get() 方法*/
public String getAccountNum(){
return accountNum;
}
public String getName(){
return name;
}
public double getBalance(){
return balance;
}
}
showBalance.jsp源代码：
<%@ page contentType="text/html;charset=GB2312" %>
<HTML>
<HEAD>
<title>JSP+Servlet+JavaBean实例</title>
</HEAD>
<H2>帐户信息显示</H2>
<BODY> <jsp:useBean id="account" scope="request" class="chapter41.account" />
<H3>欢迎您，<jsp:getProperty name="account" property="name" /> </H3>
<H4> 下面是您帐户的最新信息:</H4>
帐户编号:<jsp:getProperty name="account" property="accountNum"/>
<BR>帐户余额:<jsp:getProperty name="account" property="balance"/>
</BODY>
</HTML> web.xml配置文件：
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
<servlet>
<description>This is the description of my J2EE component</description>
<display-name>This is the display name of my J2EE component</display-name>
<servlet-name>GetAccount</servlet-name>
<servlet-class>chapter41.GetAccount</servlet-class>
</servlet> <servlet-mapping>
<servlet-name>GetAccount</servlet-name>
<url-pattern>/servlet/GetAccount</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app>
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