<%@ page language="java" contentType="text/html; charset=UTF-8"
        pageEncoding="UTF-8"%>
<%@ page import ="java.sql.*"%>
<%@ page import ="DBUtil.DBUtil"%>
<!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=utf-8">
<title>登录</title>
</head>
<body>
<center>
<form action="landservlet" method="post">
<p style="height: 20px; border: 1px solid red;text-align: center;">登录</p>
<p>
            请输入账户：<input type="text" name="id" maxlength="10">
<p/>
<p>
            请输入密码：<input type="text" name="psd" maxlength="10">
<p/>
<input type="hidden" name="method" value="land"/>
<input type="submit" name="submit" value="登录">
</form>
</center>
</body>
</html>

录入信息之后跳转到servlet界面

package BeanServlet;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import Dao.landDao;

/**
 * Servlet implementation class landservlet
 */
@WebServlet("/landservlet")
public class landservlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        //response.getWriter().append("Served at: ").append(request.getContextPath());
        //防止乱码
        response.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");
        request.setCharacterEncoding("UTF-8");

        //判断前端传来的标记，以此执行相对应的操作
        String method=request.getParameter("method");
        System.out.print(method);
        if("land".equals(method)) {
            System.out.print("开始验证");
            String id=request.getParameter("id");
            String password=request.getParameter("psd");
            int flag = landDao.land(id,password);
            if(flag != 0) {
                System.out.print("登录成功");
                request.getRequestDispatcher("index.jsp").forward(request,response);
            } else {
                System.out.print("登录失败");
                request.getRequestDispatcher("land.jsp").forward(request,response);
            }
        }
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}

注意这里让eclipse自动创建servlet

之后跳转到到层进项查询

package Dao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import DBUtil.DBUtil;

public class landDao {

    public static int land(String id, String password) {
        // TODO Auto-generated method stub
        Connection connection=null;
        PreparedStatement preparedStatement=null;
        connection= DBUtil.getConnection();
        int flag=0;
        System.out.print("即将开始查找");
        String sql="select * from land where id=? and password=?";
        try{
            System.out.print("开始查找");
            preparedStatement=connection.prepareStatement(sql);
            preparedStatement.setString(1,id);
            preparedStatement.setString(2,password);
            ResultSet resultSet = preparedStatement.executeQuery();
            while (resultSet.next()){
                String id2=resultSet.getString(1);
                String password2=resultSet.getString(2);
                String found = id2 + password2;
                if(found != null ||found.length() != 0) {
                    flag = 1;
                }
            }
            System.out.println("flag=" + flag);
            if(flag != 0) {
                System.out.print("用户信息存在");
            } else {
                System.out.print("用户信息不存在");
            }
            preparedStatement.close();
            connection.close();

        }catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }finally {
            DBUtil.close(preparedStatement,connection);
        }
        return flag;
    }

}