javaEE认不到mysql驱动

java测试代码可连接
package com.wzq.login.mysqljdbc; import java.sql.*;
public class MysqlJdbc {
  public static void main(String args[]) {
    try {
      Class.forName("com.mysql.jdbc.Driver");
      //Class.forName("org.gjt.mm.mysql.Driver");
     System.out.println("Success loading Mysql Driver!");
   }
    catch (Exception e) {
      System.out.print("Error loading Mysql Driver!");
      e.printStackTrace();
    }
    try {
      Connection connect = DriverManager.getConnection(
          "jdbc:mysql://localhost:3306/userdemo","root","123456");
      System.out.println("Success connect Mysql server!");
      Statement stmt = connect.createStatement();
      ResultSet rs = stmt.executeQuery("select * from userinfo");
      while (rs.next()) {
        System.out.println(rs.getString("username"));
      }
    }
    catch (Exception e) {
      System.out.print("get data error!");
      e.printStackTrace();
    }
  }
}
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<%@ page import="java.sql.*" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<h1>login operator</h1>
<hr>
<%
try{
%>
<%!
Connection conn = null;
PreparedStatement pstmt = null;
ResultSet rs = null;
boolean flag = false;
String name = null;
%>
<%
//Class.forName("com.mysql.jdbc.Driver");
Class.forName("org.gjt.mm.mysql.Driver").newInstance();
conn = DriverManager.getConnection(
"jdbc:mysql://localhost:3306/userdemo",
"root","123456");
%>
System.out.println("Success connect Mysql server!");
<%
Statement stmt = conn.createStatement();
    ResultSet rs = stmt.executeQuery("select * from userinfo");

    while (rs.next()){
    %>
      System.out.println(rs.getString("username"));
    <%
    }
String sql = "select username from user where userid=? and password=?";
pstmt.setString(1,request.getParameter("id"));
pstmt.setString(2,request.getParameter("password"));
if(rs.next()){
flag = true;
name = rs.getString(1);
}
%>
<%
}catch(Exception e){
e.printStackTrace();
}finally{
try{
rs.close();
pstmt.close();
conn.close();
}catch(Exception e){
e.printStackTrace();
}
}
%>
<%
if(flag){
%>
<jsp:forward page="login_success.jsp">
<jsp:param name="uname" value="<%=name %>" />
</jsp:forward>
<%
}else{
%>
<jsp:forward page="login_failure.jsp">
<jsp:param name="" value="" />
</jsp:forward>
<%
}
%>
</body>
</html>
错误提示
java.lang.ClassNotFoundException: org.gjt.mm.mysql.Driver
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1678)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1523)
at org.apache.jasper.servlet.JasperLoader.loadClass(JasperLoader.java:126)
at org.apache.jasper.servlet.JasperLoader.loadClass(JasperLoader.java:63)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Unknown Source)
at org.apache.jsp.login_005fcheck_jsp._jspService(login_005fcheck_jsp.java:90)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:433)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:389)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:333)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:304)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:224)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:185)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:151)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:929)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:405)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:269)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:515)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:300)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
java.lang.NullPointerException
at org.apache.jsp.login_005fcheck_jsp._jspService(login_005fcheck_jsp.java:124)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:433)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:389)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:333)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:304)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:224)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:185)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:151)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:929)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:405)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:269)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:515)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:300)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)

解决方案 »

免费领取超大流量手机卡，每月29元包185G流量+100分钟通话, 中国电信官方发货

你mysql的jdbc驱动加入工程的classpath，同时保证放在web-inf/lib这个目录下
按照这样做把驱动jar拷贝过去之后，重新运行一下，看看情况如何
Class.forName("com.mysql.jdbc.Driver");
有添加驱动的，要不java代码怎么测试成功的。然后按1楼同志说的做了，木用。
jdbc是用Class.forName("com.mysql.jdbc.Driver");这个，
然后导入mysql-connecter-java.jar