初学JSP，TOMCAT5.5 + J2SDK1.5 + MSSQL-JDBC，写的最简单程序，出现如下错误，原因何在？

TOMCAT已正确配置，因为访问http://localhost/完全正常；

MSSQL-JDBC已安装，并将三个jar文件加入了CLASSPATH中。

写的最简单程序片段如下：

<%@ page contentType="text/html;charset=gb2312"%>
<%@ page import="java.sql.*"%>

<html>
<body>

<%
Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver").newInstance();

String url="jdbc:microsoft:sqlserver://wjserver:1433;DatabaseName=master";
String user="sa";
String password="";

Connection conn= DriverManager.getConnection(url,user,password);

Statement stmt=conn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE);

String sql="select * from emp_basic";
ResultSet rs=stmt.executeQuery(sql);




结果得到如下错误：

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: /test_jdbc.jsp:11

8:
9: <%
10:
11: Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver").newInstance();
12:
13: String url="jdbc:microsoft:sqlserver://wjserver:1433;DatabaseName=master";
14:


Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:504)
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

javax.servlet.ServletException: com.microsoft.jdbc.sqlserver.SQLServerDriver
org.apache.jasper.runtime.PageContextImpl.doHandlePageException(PageContextImpl.java:858)
org.apache.jasper.runtime.PageContextImpl.handlePageException(PageContextImpl.java:791)
org.apache.jsp.test_005fjdbc_jsp._jspService(org.apache.jsp.test_005fjdbc_jsp:113)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:332)
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

java.lang.ClassNotFoundException: com.microsoft.jdbc.sqlserver.SQLServerDriver
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1352)
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1198)
org.apache.jasper.servlet.JasperLoader.loadClass(JasperLoader.java:127)
org.apache.jasper.servlet.JasperLoader.loadClass(JasperLoader.java:65)
java.lang.ClassLoader.loadClassInternal(Unknown Source)
java.lang.Class.forName0(Native Method)
java.lang.Class.forName(Unknown Source)
org.apache.jsp.test_005fjdbc_jsp._jspService(org.apache.jsp.test_005fjdbc_jsp:53)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:332)
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/5.5.15 logs.


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Apache Tomcat/5.5.15



不知是何原因。