简单案例：用户登录

程序员文章站 2022-03-26 17:10:26

案例：用户登录用户登录案例需求：1.编写login.html登录页面 username & password 两个输入框2.使用Druid数据库连接池技术,操作mysql，day14数据库中user表3.使用JdbcTemplate技术封装JDBC4.登录成功跳转到SuccessServlet展示：登录成功！用户名,欢迎您5.登录失败跳转到FailServlet展示：登录失败，用户名或密码错误整体思路：开发步骤创建项目，导入html页面，配置文件，jar包创建数据库环境C...

简单案例：用户登录

用户登录案例需求：

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

整体思路：

简单案例：用户登录

开发步骤

创建项目，导入html页面，配置文件，jar包

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

配置文件druid.properties：

driverClassName=com.mysql.cj.jdbc.Driver
url=jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone = GMT
username=root
password=123456
initialSize=5
maxActive=10
maxWait=3000

引入的jar包
简单案例：用户登录

创建数据库环境

CREATE DATABASE test;
USE test;
CREATE TABLE USER ( id INT PRIMARY KEY auto_increment, username VARCHAR ( 32 ) UNIQUE NOT NULL, PASSWORD VARCHAR ( 32 ) NOT NULL );

创建包com.ccit.rj1842.domain，创建类User

package com.ccit.rj1842.domain;

/**
 * 用户的实体类
 */
public class User {
    private int id;
    private String username;
    private String password;

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

创建包com.ccit.rj1842.util,编写工具类JDBCUtils

package com.ccit.rj1842.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;

/**
 * JDBC工具类，使用Durid连接池
 */
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
            DataSource 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com.ccit.rj1842.dao，创建UserDao,提供login方法

package com.ccit.rj1842.dao;

import com.ccit.rj1842.domain.User;
import com.ccit.rj1842.util.JDBCUtils;
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
     */
    public User login(User loginUser) {
        //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>(User.class),
                loginUser.getUsername(), loginUser.getPassword());
        return user;
    }
}

编写com.ccit.rj1842.web.servlet.LoginServlet类

package com.ccit.rj1842.web.servlet;

import com.ccit.rj1842.dao.UserDao;
import com.ccit.rj1842.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;

@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) {
            //登陆失败
            req.getRequestDispatcher("/failServlet").forward(req,resp);
        } else {
            //登陆成功
            //存储数据
            req.setAttribute("user",user);
            req.getRequestDispatcher("/successServlet").forward(req,resp);
        }
    }

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

编写编写FailServlet和SuccessServlet类

package com.ccit.rj1842.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 {
        //设置页面编码
        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);
    }
}

package com.ccit.rj1842.web.servlet;

import com.ccit.rj1842.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;

@WebServlet("/successServlet")
public class SuccessServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //获取request域*享的user对象
        User user = (User) request.getAttribute("user");

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

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

运行的截图

用户名和密码输入正确：
简单案例：用户登录

用户名或密码输入错误：
简单案例：用户登录

本文地址：https://blog.csdn.net/qq_45154678/article/details/109249537

简单案例：用户登录