在servlet中添加进行数据库操作的语句怎么写（写了很多都不能运行）

Question

package Servlet;

import java.io.IOException;

import java.sql.SQLException;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import javax.servlet.http.HttpSession;

import Dao.loginDao;

public class loginServlet extends HttpServlet {

public void doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

doPost(request, response);

}

public void doPost(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

request.setCharacterEncoding("utf-8");

response.setCharacterEncoding("utf-8");

String method= request.getParameter("method");

if ("login".equals(method)) {

login(request, response);

}

}

public void login(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

String user=request.getParameter("user");

String password=request.getParameter("password");

System.out.println(user);

System.out.println(password);

loginDao ld = new loginDao();

//boolean login = userDaoImpl.login(userID, passWord);

if (1 == 1) {

//HttpSession session = request.getSession();

//session.setAttribute("userID", userID);

//session.setAttribute("passWord", passWord);

request.getRequestDispatcher("index.jsp").forward(request, response);

}else {

request.getRequestDispatcher("fail.jsp").forward(request, response);

}

   }

  public void find (HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

  HttpSession session = request.getSession();

    String userID = (String)session.getAttribute("userID");

     

  }

}

package Dao;

import java.sql.Connection;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

import Bean.login;

import Util.DBUtil;

public class loginDao {

public static Bean.login login(String user) throws SQLException{             //static Bean.login根据提示修改

String sql = "select * from user where user_name ='" +user+"'";

Connection con = DBUtil.getConnection();

Statement stmd = con.prepareStatement(null);

ResultSet rs = stmd.executeQuery(sql);

while(rs.next()){

login u = new login();

    u.setUser(rs.getString("user"));

    u.setPassword(rs.getString("password"));

    return null;

}

return null;

}

}

Answer 1

你用PreparedStatement对象，你的sql语句怎么还在拼接额。