public class Servlet01 extends HttpServlet {
    
    protected void service(HttpServletRequest req,HttpServletResponse resp)throws ServletException,java.io.IOException{
        String name= req.getParameter("name");
        GetJdbc gj=new GetJdbc();
        boolean flag=gj.getIn(name);
        if(flag==true){
            RequestDispatcher rd=req.getRequestDispatcher("Yes.jsp");//。forward方式只能跳转到本web应用中的页面上。
            req.setAttribute(name, "name");
            System.out.print(name);
            rd.forward(req, resp);//跳转
        }
        
    }
}

package com.cme.cen;

import java.sql.*;

public class GetJdbc {
    String driverName = "com.microsoft.sqlserver.jdbc.SQLServerDriver";// 将驱动器的包名和类名存储到字符串中
    String dbURL = "jdbc:sqlserver://localhost:1433;DatabaseName=Sales"; // 将数据库StuInfo的路径存储到字符串中
    String userName = "sa"; // 默认用户名
    String userPwd = "19881212"; // 安装sql server 2005时的密码
    Statement sm = null;
    public static Connection dbConn = null;// 定义打开了的接口对象
    ResultSet rs = null;

    // 构造方法
    public GetJdbc() {
        try {
            Class.forName(driverName);
            dbConn = DriverManager.getConnection(dbURL, userName, userPwd);
            sm = dbConn.createStatement();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public boolean getIn(String name){
        String sql="select * from Employees";
        boolean flag=false;
        try {
            rs = sm.executeQuery(sql);
            while(rs.next()){
                if(rs.getString("姓名").trim().equals(name)){
                    flag=true;
                }
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return flag;
    }
}