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Java--用户登录（JDBC，MYSQL，Servlet）

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用户登录案例需求

编写login.html登录页面
username & password 两个输入框
使用Druid数据库连接池技术,操作mysql，day14数据库中user表
使用JdbcTemplate技术封装JDBC
登录成功跳转到SuccessServlet展示：登录成功！用户名,欢迎您
登录失败跳转到FailServlet展示：登录失败，用户名或密码错误

登录页面

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <form action="/login_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>

创建数据库

CREATE DATABASE login;

USE login;

CREATE TABLE user(
    id INT PRIMARY KEY auto_increment,
    username VARCHAR(32) UNIQUE NOT NULL,
    password VARCHAR(32) NOT NULL
)

配置文件

driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql:///login
username=root
password=root
initialSize=5
maxActive=10
maxWait=3000

项目依赖

Java--用户登录（JDBC，MYSQL，Servlet）

创建用户实体类

创建包cn.guizimo.domain,创建类User

package cn.guizimo.domain;

/**
 * @author tanglei
 * @date 2020/6/22 10:28 上午
 */
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 "User{" +
                "id=" + id +
                ", username='" + username + '/'' +
                ", password='" + password + '/'' +
                '}';
    }
}

创建工具类

创建包cn.guizimo.util,编写工具类JDBCUtils

package cn.guizimo.util;

import com.alibaba.druid.pool.DruidDataSourceFactory;

import javax.sql.DataSource;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.Properties;

/**
 * @author tanglei
 * @date 2020/6/22 10:38 上午
 */
public class JDBCUtils {
    private static DataSource ds ;

    static {

        try {
            //1.加载配置文件
            Properties pro = new Properties();
            //使用ClassLoader加载配置文件，获取字节输入流
            InputStream is = JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties");
            pro.load(is);

            //2.初始化连接池对象
            ds = DruidDataSourceFactory.createDataSource(pro);

        } catch (IOException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 获取连接池对象
     */
    public static DataSource getDataSource(){
        return ds;
    }


    /**
     * 获取连接Connection对象
     */
    public static Connection getConnection() throws SQLException {
        return  ds.getConnection();
    }

}

创建数据操作类

创建包cn.guizimo.dao,创建类UserDao,提供login方法

package cn.guizimo.dao;

import cn.guizimo.domain.User;
import cn.guizimo.util.JDBCUtils;
import org.springframework.dao.DataAccessException;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;

/**
 * @author tanglei
 * @date 2020/6/22 10:34 上午
 */
public class UserDao {


    private JdbcTemplate template = new JdbcTemplate(JDBCUtils.getDataSource());

    public User login(User loginUser) {
        try {
            String sql = "select * from user where username = ? and password = ?";
            User user = template.queryForObject(sql,
                    new BeanPropertyRowMapper<User>(User.class),
                    loginUser.getUsername(), loginUser.getPassword());
            return user;
        } catch (DataAccessException e) {
            e.printStackTrace();
            return null;
        }
    }
}

创建servlet类

cn.guizimo.web.servlet.LoginServlet类

package cn.guizimo.web.servlet;

import cn.guizimo.dao.UserDao;
import cn.guizimo.domain.User;

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;

/**
 * @author tanglei
 * @date 2020/6/22 11:15 上午
 */

@WebServlet("/loginServlet")
public class LoginServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //1.设置编码
        req.setCharacterEncoding("utf-8");
        //2.获取请求参数
        String username = req.getParameter("username");
        String password = req.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
            req.getRequestDispatcher("/failServlet").forward(req,resp);
        }else{
            //登录成功
            //存储数据
            req.setAttribute("user",user);
            //转发
            req.getRequestDispatcher("/successServlet").forward(req,resp);
        }
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doGet(req,resp);
    }
}

cn.guizimo.web.servlet.FailServlet类

package cn.guizimo.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;

/**
 * @author tanglei
 * @date 2020/6/22 11:26 上午
 */
@WebServlet("/failServlet")
public class FailServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doPost(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //设置编码
        resp.setContentType("text/html;charset=utf-8");
        //输出
        resp.getWriter().write("登录失败，用户名或密码错误");

    }
}

cn.guizimo.web.servlet.SuccessServlet类

package cn.guizimo.web.servlet;

import cn.guizimo.domain.User;

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;

/**
 * @author tanglei
 * @date 2020/6/22 11:31 上午
 */
@WebServlet("/successServlet")
public class SuccessServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doPost(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //获取request域中共享的user对象
        User user = (User) req.getAttribute("user");

        if(user != null){
            //设置编码
            resp.setContentType("text/html;charset=utf-8");
            //输出
            resp.getWriter().write("登录成功！"+user.getUsername()+",欢迎您");
        }
    }
}