Java+MySQL实现简单登录功能

package dao;

import java.sql.Connection;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import er;

import utils.DataBaseUtil;

public class UserDao {

public User login(String username,String pwd){

User user=null;

//获取数据库连接

Connection conn=DataBaseUtil.getConnection();

String sql="select * from tb_user where username=? and password=?";

try {

PreparedStatement ps=conn.prepareStatement(sql);

ps.setString(1, username);

ps.setString(2, pwd);

//用ResultSet存储查到的内容

ResultSet rs=ps.executeQuery();

if(rs.next()){//查到了数据

user =new User();

user.setUsername(rs.getString("username"));//username代表的是tb_user表的username字段

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

user.setSex(rs.getString("sex"));

user.setPhone(rs.getString("phone"));

user.setEmail(rs.getString("email"));

}

//将用户名和密码带入到占位符？中

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

return user;

}

}

package servlet;

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 erDao;

import er;

/**

* Servlet implementation class LoginServlet

*/

@WebServlet("/LoginServlet")//门牌号

public class LoginServlet extends HttpServlet {

private static final long serialVersionUID = 1L;

/**

* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)

*/

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

// TODO Auto-generated method stub

response.getWriter().append("Served at: ").append(request.getContextPath());

}

/**

* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)

*/

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

//设置字符编码

request.setCharacterEncoding("utf-8");

//获取页面的账号和密码

String username=request.getParameter("username");//对应前台name属性

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

System.out.println("账号："+username+","+"密码："+password);

UserDao dao=new UserDao();

User user=dao.login(username, password);

//判断用户名是否正确

if(user!=null){//跳转登陆成功的页面

//将user对象通过session传递到前台页面

request.getSession().setAttribute("user", user);

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

}else{//跳失败页面

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

}

}

}

package utils;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.SQLException;

/**

*

* 数据库联连接工具类

*/

public class DataBaseUtil {

public static Connection getConnection(){

Connection conn=null;

//获取驱动

try {

Class.forName("com.mysql.jdbc.Driver");

String url="jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf8";

conn=DriverManager.getConnection(url,"root","123456");