HTTP Status 500 -org.apache.jasper.JasperException: Exception in JSP

加载的代码，500了....新手啊，真心不懂啊，求解~~

HTTP 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: Exception in JSP: /index.jsp:2

1: <%@ page language="java" contentType="text/html; charset=gb2312"%>
2: <jsp:forward page="IndexServlet"/>

Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:451)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:373)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:329)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)

root cause

java.lang.NullPointerException
com.yxq.dao.FriendDao.queryFriend(FriendDao.java:47)
com.yxq.servlet.IndexServlet.doPost(IndexServlet.java:52)
com.yxq.servlet.IndexServlet.doGet(IndexServlet.java:25)
javax.servlet.http.HttpServlet.service(HttpServlet.java:627)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.jasper.runtime.PageContextImpl.doForward(PageContextImpl.java:686)
org.apache.jasper.runtime.PageContextImpl.forward(PageContextImpl.java:656)
org.apache.jsp.index_jsp._jspService(index_jsp.java:45)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:98)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:331)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:329)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)

note The full stack trace of the root cause is available in the Apache Tomcat/5.5.28 logs.

是不是index.jsp有问题啊，但是里面就2句啊：
<%@ page language="java" contentType="text/html; charset=gb2312"%>
<jsp:forward page="IndexServlet"/>

我看好多帖子说好像跟web.xml有关系啊，这是web.xml里的代码，求大家看看，我真心不懂啊：
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4">
  <servlet>
    <servlet-name>indexServlet</servlet-name>
    <servlet-class>com.yxq.servlet.IndexServlet</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>articleServlet</servlet-name>
    <servlet-class>com.yxq.servlet.ArticleServlet</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>photoServlet</servlet-name>
    <servlet-class>com.yxq.servlet.PhotoServlet</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>friendServlet</servlet-name>
    <servlet-class>com.yxq.servlet.FriendServlet</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>wordServlet</servlet-name>
    <servlet-class>com.yxq.servlet.WordServlet</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>logonServlet</servlet-name>
    <servlet-class>com.yxq.servlet.LogXServlet</servlet-class>
  </servlet>

  <servlet-mapping>
    <servlet-name>indexServlet</servlet-name>
    <url-pattern>/IndexServlet</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>articleServlet</servlet-name>
    <url-pattern>/ArticleServlet</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>photoServlet</servlet-name>
    <url-pattern>/PhotoServlet</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>friendServlet</servlet-name>
    <url-pattern>/FriendServlet</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>wordServlet</servlet-name>
    <url-pattern>/WordServlet</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>logonServlet</servlet-name>
    <url-pattern>/LogonServlet</url-pattern>
  </servlet-mapping>
</web-app>

异常 JSP Servlet MyEclipse HTTP500 --------------------编程问答-------------------- 现在网页又能访问，真搞不懂，不过有时候可以访问，但访问另一个页面时有时候会404，有时候返回的时候也会404：

--------------------编程问答-------------------- 我和你一样的问题，请问你找到答案了吗 --------------------编程问答-------------------- <jsp:forward page="IndexServlet"/>这个跳转目标Servlet应该使用了queryFriend方法。
因为有错误日志：
java.lang.NullPointerException
com.yxq.dao.FriendDao.queryFriend(FriendDao.java:47)
检查下FriendDao类的47行就知道哪个对象为空了。

500是服务器内部错误，一般是你的代码出错了。
404一般是请求的路径不对。

补充：Java ,  Eclipse