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向大侠们求救！！！ 想要显示jsp页面时出现HTTP Status 500 - An exception occurred processing JSP page

2013-10-25 15:47 465 查看
错误描述：

 

HTTP Status 500 - An exception occurred processing JSP page /main.jsp at line 23

 

 

type Exception report

message An exception occurred processing JSP page /main.jsp at line 23

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

exception

org.apache.jasper.JasperException: An exception occurred processing JSP page /main.jsp at line 23

20:
21:   			<%
22:   				ArrayList al=(ArrayList)session.getAttribute("al");
23:  				Iterator iter=al.iterator();
24:
25:   				while(iter.hasNext()){
26:   					LyTable ly=(LyTable)iter.next();

Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:568)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:470)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
javax.servlet.http.HttpServlet.service(HttpServlet.java:728)


root cause

java.lang.NullPointerException
org.apache.jsp.main_jsp._jspService(main_jsp.java:88)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
javax.servlet.http.HttpServlet.service(HttpServlet.java:728)


note The full stack trace of the root cause is available in the Apache Tomcat/7.0.42 logs.

 

 

Apache Tomcat/7.0.42

代码：

<%@ page language="java" import="java.util.*" pageEncoding="gb2312"%>

<%@ page import="model.LyTable" %>

<%@ page import="db.DB" %>

<html>

  <head>

    <title>留言板信息</title>

   

  </head>

 

  <body  bgcolor="#E3E3E3">

    <form action="liuyan.jsp" method="post">

     <table border="1">

      <caption>所有留言信息</caption>

      <tr><th>留言人姓名</th>

          <th>留言标题</th>

       <th>留言内容</th>

      

      </tr>

      

     <%

      ArrayList al=(ArrayList)session.getAttribute("al");

     Iterator iter=al.iterator();

 

      while(iter.hasNext()){

       LyTable ly=(LyTable)iter.next();

     

      %>

     

        <tr>

         <td><%= new DB().getUserName(ly.getUserId()) %></td>

         <td><%=ly.getDate().toString() %></td>

         <td><%= ly.getTitle() %></td>

         <td><%=ly.getContent() %></td>

        </tr>

     

      <%

       }

     

       %>

     

     </table>

     <input type="submit" value="留言"/>

    

    

    

    

    </form>

   

  </body>

</html>

 

 

附加：根据提示显示23行有错，怎么就找不出呢！！！

 

 
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标签：  jsp
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