执行这段代码，返回HTTP Status 500，啥原因。。
<%@page contentType="text/html; charset=gb2312" language="java" import="java.sql.*" errorPage="" %><html>
<head>
<title>留言本</title>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<link href="images/web.css" rel="stylesheet" type="text/css">
</head>
<script language="JavaScript">
function openw(url) {
var newwin=window.open(url,"NewWin","toolbar=no,resizable=no,location=no,directories=no,status=no,menubar=no,scrollbars=no,top=220,left=220,width=500,height=330");
// newwin.focus();
return false;
}
function opend(url) {
var newwin=window.open(url,"NewWin","toolbar=no,resizable=yes,location=no,directories=no,status=no,menubar=no,scrollbars=no,top=100,left=50,width=650,height=350");
// newwin.focus();
return false;
}
</script>
<body leftmargin="0" topmargin="1">
<jsp:useBean id="wu" scope="page" class="wu.jdbc" />
<%
Connection con = wu.getConn() ;
Statement stmt = con.createStatement() ;
String sql = "select * from liuyan_temp order by id desc" ;
ResultSet rs = stmt.executeQuery(sql) ;
String pages = request.getParameter("page") ;
int pageInt = 1 ,i=1;
if(pages==null){}else{pageInt = Integer.parseInt(pages);}
while(i<20*(pageInt-1)&&rs.next()){i++ ;}
%>
<table width="775" border="0" align="center" cellpadding="0" cellspacing="1">
<tr>
<td align="center"><img src="images/flag.gif" width="160" height="59" border="0"><img src="images/logo.gif" width="600" height="59" border="1"></td>
</tr>
<tr>
<td>
<table width="100%" border="0" cellpadding="2" cellspacing="1" bgcolor="#16831C">
<tr>
<td colspan="2" bgcolor="#E8FCE2">
<div align="center">
<table width="100%" border="0" cellpadding="1" cellspacing="1">
<tr>
<td><div align="center"><a href="#" onClick="return opend('ly_new.jsp')">添加留言</a></div></td>
<td><div align="center"><a href="http://www.china1024.com">返回主页</a></div></td>
<td><div align="center"><a href="login.jsp">留言管理</a></div></td>
<td><div align="center"><a href="#" onClick="return opend('my.jsp')">我的介绍</a></div></td>
</tr>
</table>
</div></td>
</tr>
<%
i=0 ;
String str = "#E8FCE2",str1="" ;
java.util.Random rd = new java.util.Random() ;
while(rs.next()&i<20){
i++ ;
String id = rs.getString("id") ;
String sj = rs.getString("sj") ;
String url = rs.getString("url") ;
String ip = rs.getString("ip") ;
String email = rs.getString("email") ;
String qq = rs.getString("qq") ;
String content = rs.getString("content") ;
String xm = rs.getString("xm") ;
if(str.equals("#E8FCE2")){
str = "#D1E79E" ;}else{
str = "#E8FCE2" ;
}
%>
<tr>
<td width="23%" bgcolor="<%=str%>">
<div align="center"><%=sj%></div></td>
<td width="77%" bgcolor="<%=str%>">
<table width="100%" border="0" cellpadding="0" cellspacing="0">
<tr>
<td> <div align="center"><a href="<%=url%>"><img src="images/HOME.gif" alt="个人主页" width="16" height="16" border="0" align="absmiddle"></a>留言人主页</div></td>
<td> <div align="center"><img src="images/ip.gif" alt="<%=ip%>" width="13" height="15" align="absmiddle">留言人IP</div></td>
<td> <div align="center"><a href="mailto:<%=email%>"><img src="images/EMAIL.gif" alt="<%=email%>" width="16" height="16" border="0" align="absmiddle"></a>留言人email</div></td>
<td> <div align="center"><img src="images/oicq.gif" alt="<%=qq%>" width="16" height="16" align="absmiddle">留言人QQ</div></td>
<td>
<div align="center"><a href="del.jsp?id=<%=id%>"><img src="images/dele_1.gif" alt="删除" width="14" height="16" border="0" align="absmiddle">删除留言</div>
</a></td>
</tr>
</table></td>
</tr>
<tr>
<td align="center" valign="middle" bgcolor="<%=str%>"><img src="images/tx/<%=rd.nextInt(30)+1%>.gif" width="100" height="100"><br>
<br>
留言人：
<%=xm%> </td>
<td bgcolor="#FFFFFF" style="word-break:break-all">
<%=content%>
</td>
</tr>
<%
}
%>
<tr bgcolor="#F9CDBB">
<td> </td>
<%
sql = "select count(*) from liuyan_temp" ;
rs = stmt.executeQuery(sql) ;
while(rs.next()) i = rs.getInt(1) ;
%>
<td>
<div align="right">总共有留言<%=i%>条/<%=(i+19)/20%>页，这是第<%=pageInt%>页，转到第
<%
for(int j=1;j<(i+40)/20;j++){
%>
<a href="ly.jsp?page=<%=j%>">^<%=j%>^</a>
<%
}
try {
rs.close();
stmt.close();
con.close();
}
catch (Exception ex) {
}
%>
页</div></td>
</tr>
<tr>
<td bgcolor="<%=str%>"> </td>
<td bgcolor="<%=str%>"> </td>
</tr>
</table></td>
</tr>
<tr>
</table>
</body>
</html>
返回的结果：TTP Status 500 -
type Exception report
message
description The server encountered an internal error () that prevented it from fulfilling this request.
exception
org.apache.jasper.JasperException: /liuyanben/ly.jsp(21,0) The value for the useBean class attribute wu.jdbc is invalid.
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:510)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:375)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
root cause
org.apache.jasper.JasperException: /liuyanben/ly.jsp(21,0) The value for the useBean class attribute wu.jdbc is invalid.
org.apache.jasper.compiler.DefaultErrorHandler.jspError(DefaultErrorHandler.java:39)
org.apache.jasper.compiler.ErrorDispatcher.dispatch(ErrorDispatcher.java:405)
org.apache.jasper.compiler.ErrorDispatcher.jspError(ErrorDispatcher.java:146)
org.apache.jasper.compiler.Generator$GenerateVisitor.visit(Generator.java:1223)
org.apache.jasper.compiler.Node$UseBean.accept(Node.java:1116)
org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2163)
org.apache.jasper.compiler.Node$Visitor.visitBody(Node.java:2213)
org.apache.jasper.compiler.Node$Visitor.visit(Node.java:2219)
org.apache.jasper.compiler.Node$Root.accept(Node.java:456)
org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2163)
org.apache.jasper.compiler.Generator.generate(Generator.java:3284)
org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:198)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:295)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:276)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:264)
org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:563)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:303)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
note The full stack trace of the root cause is available in the Apache Tomcat/5.5.14 logs. --------------------编程问答-------------------- 不是页面问题
http://www.cnblogs.com/feiweiwei/archive/2007/12/05/984484.html --------------------编程问答--------------------
不是页面问题。。。http://www.cnblogs.com/feiweiwei/archive/2007/12/05/984484.html --------------------编程问答-------------------- <jsp:useBean id="wu" scope="page" class="wu.jdbc" />
“org.apache.jasper.JasperException: /liuyanben/ly.jsp(21,0) The value for the useBean class attribute wu.jdbc is invalid.”提示上面的语句的 class属性不正确，应是：class="***.class"
--------------------编程问答-------------------- /liuyanben/ly.jsp(21,0) The value for the useBean class attribute wu.jdbc is invalid.
看看jsp这行
1.看看useBeen 忘记写get()set()方法
2.查看连接数据是否有问题,jdbc驱动包
3.bean虽然找到了,但不是静态的，或者找到class是静态的
--------------------编程问答-------------------- org.apache.jasper.JasperException: /liuyanben/ly.jsp(21,0) The value for the useBean class attribute wu.jdbc is invalid.
补充：Java , Web 开发
