Mysql驱动配置有关问题有关问题

package sime.login.servlet;import java.sql.Statement;import java.io.IOException;import java.sql.DriverManager;import java.sql.ResultSet;import java.sql.SQLException;import javax.servlet.Servlet;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class LoginServlet extends HttpServlet implements Servlet{public LoginServlet (){// TODO Auto-generated constructor stub}/** (non-Javadoc)** @see javax.servlet.http.HttpServlet#doGet(javax.servlet.http.HttpServletRequest,* javax.servlet.http.HttpServletResponse)*/@Overrideprotected void doGet ( HttpServletRequest arg0, HttpServletResponse arg1 )   throws ServletException, IOException{}/** (non-Javadoc)** @see javax.servlet.http.HttpServlet#doPost(javax.servlet.http.HttpServletRequest,* javax.servlet.http.HttpServletResponse)*/@Overridepublic void doPost ( HttpServletRequest request, HttpServletResponse response )   throws ServletException, IOException{response.setContentType ( "text/html" );String result = "";// 获取用户名String sUserName = request.getParameter ( "txtUserName" );if ( sUserName == "" || sUserName == null || sUserName.length ( ) > 20 ){   try   {    result = "请输入用户名（不超过20字符）！";    request.setAttribute ( "ErrorUserName", result );    response.sendRedirect ( "login.html" );   } catch ( Exception e )   {   }}// 获取密码String sPasswd = request.getParameter ( "txtPassword" );if ( sPasswd == "" || sPasswd == null || sPasswd.length ( ) > 20 ){   try   {    result = "请输入密码（不超过20字符）！";    request.setAttribute ( "ErrorPassword", result );    response.sendRedirect ( "login.html" );   } catch ( Exception e )   {   }}// 登记JDBC驱动程序try{   Class.forName ( "org.gjt.mm.mysql.Driver" ).newInstance ( );} catch ( InstantiationException e ){   // TODO Auto-generated catch block   e.printStackTrace ( );   System.out.println ("InstantiationException");} catch ( IllegalAccessException e ){   // TODO Auto-generated catch block   e.printStackTrace ( );   System.out.println ("IllegalAccessException");} catch ( ClassNotFoundException e ){   // TODO Auto-generated catch block   e.printStackTrace ( );   System.out.println ("ClassNotFoundException");}// 连接参数与Access不同String url = "jdbc:mysql://localhost/learnJSP";// 建立连接java.sql.Connection connection = null;Statement stmt = null;ResultSet rs = null;try{   connection = DriverManager.getConnection ( url, "root", "woshipis" );   stmt = connection.createStatement ( );   // SQL语句   String sql = "select * from logintest where Username='" + sUserName     + "' and Userpwd = '" + sPasswd + "'";   rs = stmt.executeQuery ( sql );// 返回查询结果} catch ( SQLException e ){   // TODO Auto-generated catch block   e.printStackTrace ( );}try{   if (rs.next())// 如果记录集非空，表明有匹配的用户名和密码，登陆成功   {    // 登录成功后将sUserName设置为session变量的UserName    // 这样在后面就可以通过 session.getAttribute("UserName") 来获取用户名，    // 同时这样还可以作为用户登录与否的判断依据    request.getSession ( ).setAttribute ( "UserName", sUserName );    response.sendRedirect ( "login_success.jsp" );   } else   {    // 否则登录失败    //response.sendRedirect ( "MyJsp.jsp" );    response.sendRedirect ( "login_failure.jsp" );   }} catch ( SQLException e ){   // TODO Auto-generated catch block   e.printStackTrace ( );}try{   if ( null!=rs )   {    rs.close ( );   }   if ( null!=stmt )   {    stmt.close ( );   }   if ( null!=connection )   {    connection.close ( );   }} catch ( SQLException e ){   // TODO Auto-generated catch block   e.printStackTrace ( );}}/****/private static final long serialVersionUID = 1L;}