登录案例_代码实现1与登录案例_代码实现2

登录案例_代码实现1

　　　　开发项目：用户登录

　　　　　　　开发步骤：

　　　　　　　　　　1.创建项目，导入html页面，配置文件，jar包

　　　　　　　　　　2.创建数据库的环境

CREATE DATABASE day14;


USE day014;


CREATE TABLE USER(
  id  INT  PRIMARY KEY  AUTO_INCREMENT,
  USER    VARCHAR(32) UNIQUE NOT NULL,
  PASSWORD VARCHAR(32) NOT NULL            
);

　　　　　　　　　　3.创建包com.example.day014_userlogin.domain，创建一个类User

package com.example.day014_userlogin.domain;

/**
 * 用户实体类
 */
public class User{

    private int id;
    private String username;
    private String password;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    @Override
    public String toString() {
        return "Uesr{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                '}';
    }
}

　　　　　　　　4.创建包com.example.day014_userlogin.dao，创建类UserDao，提供login方法

package com.example.dao;


import com.example.domain.User;
import com.example.util.JDBCUtils;
import org.springframework.dao.DataAccessException;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;

/**
 * 操作数据库中User表的类
 */
public class UserDao {

    //声明JDBCTemplate对象共用
    private JdbcTemplate template = new JdbcTemplate(JDBCUtils.getDataSource());

    /**
     * 登录方法
     * @param loginUser 只有用户名和密码
     * @return user包含用户全部数据,没有查询到，返回null
     */
    public User login(User loginUser){
        try {
            //1.编写sql
            String sql = "select * from user where username = ? and password = ?";
            //2.调用query方法
            User user = template.queryForObject(sql,
                    new BeanPropertyRowMapper<>(User.class),
                    loginUser.getUsername(), loginUser.getPassword());


            return user;
        } catch (DataAccessException e) {
            e.printStackTrace();//记录日志
            return null;
        }
    }
}

　　　　　　　　　　　5.创建包com/example/test，创建UserDaoTest

package com.example.test;


import com.example.dao.UserDao;
import com.example.domain.User;
import org.junit.Test;

public class UserDaoTest {



    @Test
    public void testLogin(){
        User loginuser = new User();
        loginuser.setUsername("ikun");
        loginuser.setPassword("123");


        UserDao dao = new UserDao();
        User user = dao.login(loginuser);

        System.out.println(user);
    }
}

登录案例_代码实现2

　　　　　　6.编写com/example/web/servlet类

FailServlet

package com.example.web.servlet;

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 java.io.IOException;

@WebServlet("/FailServlet")
public class FailServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //给页面写一句话

        //设置编码
        response.setContentType("text/html;charset=utf-8");
        //输出
        response.getWriter().write("登录失败，用户名或密码错误");

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request,response);
    }
}

SuccessServlet

package com.example.web.servlet;

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 java.io.IOException;

@WebServlet("/FailServlet")
public class FailServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //给页面写一句话

        //设置编码
        response.setContentType("text/html;charset=utf-8");
        //输出
        response.getWriter().write("登录失败，用户名或密码错误");

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request,response);
    }
}

LoginServlet

package com.example.web.servlet;

import com.example.dao.UserDao;
import com.example.domain.User;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;

@WebServlet("/loginServlet")
public class  LoginServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
        //1.设置编码
        request.setCharacterEncoding("utf-8");
        //2.获取请求参数
        String username = request.getParameter("username");
        String password = request.getParameter("password");
        //3.封装user对象
        User loginuser = new User();
        loginuser.setUsername(username);
        loginuser.setPassword(password);


        //4.调用UserDao的login方法
        UserDao dao = new UserDao();
        User user = dao.login(loginuser);


        //5.判断user
        if (user == null){
            //登录失败
            request.getRequestDispatcher("/FailServlet").forward(request,response);
        }else {
            //登录成功
            //存储数据
            request.setAttribute("user",user);
            //转发
            request.getRequestDispatcher("/SuccessServlet").forward(request,response);

        }



    }

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

            this.doGet(request,response);

    }
}

　　　　　7.login.html中form表单的action路径的写法

　　　　　　　　　虚拟目录+Servlet的资源路径　

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<form action="/day14_test/loginServlet" method="post">
    用户名:<input type="text" name="username"> <br>
    密码:<input type="password" name="password"><br>

    <input type="submit" value="登录">

</form>
</body>
</html>