JavaEE 小项目：用户登录

项目需求

开发步骤

1. 创建项目，编写html页面，配置文件，导入jar包

2. 创建数据库环境

3. 创建包domain，创建类User

4. 创建包util，编写工具类JDBCUtils

5. 创建包dao，创建类UserDao，提供login方法

6. 创建包servlet，创建类LoginServlet

7. 编写FailServlet 和 SuccessServlet类

包、类层级结构

项目需求

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，userinfo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！

开发步骤

1. 创建项目，编写html页面，配置文件，导入jar包

html页面：
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

<form action="/test_login/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>
注意：虚拟目录不唯一，可在此处查看或自行设置

配置文件：druid.properties
driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql:///userinfo
username=root(数据库账号)
password=root(数据库密码)
initialSize=5
maxActive=10
maxWait=3000
导入jar包：注意要加载到此工程或模块下。

链接：https://pan.baidu.com/s/1R6gB5pdxpgCsDdddjzlWSA
提取码：oh01

2. 创建数据库环境

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

添加一条数据：

3. 创建包domain，创建类User

package 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 "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                '}';
    }
}

4. 创建包util，编写工具类JDBCUtils

package util;

import com.alibaba.druid.pool.DruidDataSourceFactory;

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

//JDBC连接池 使用Druid连接池
public class JDBCUtils {
    private static DataSource ds;

    //静态代码块
    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 (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();
    }
}

5. 创建包dao，创建类UserDao，提供login方法

package dao;

import domain.User;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;
import util.JDBCUtils;

//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
    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 (Exception e){
            e.printStackTrace();  //记录日志
            return null;
        }
    }
}

6. 创建包servlet，创建类LoginServlet

package servlet;

import dao.UserDao;
import domain.User;
import org.apache.commons.beanutils.BeanUtils;

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;
import java.lang.reflect.InvocationTargetException;
import java.util.Map;

@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);*/

        //获取所有请求参数
        Map<String, String[]> map = req.getParameterMap();
        //创建User对象
        User loginUser = new User();
        //使用BeanUtils封装
        try {
            BeanUtils.populate(loginUser, map);
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        }

        //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);
            req.getRequestDispatcher("/successServlet").forward(req, resp);
        }
    }

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

7. 编写FailServlet 和 SuccessServlet类

package 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 {
        //打印提示信息
        //设置页面编码
        response.setContentType("text/html;charset=utf-8");
        //输出
        response.getWriter().write("登陆失败！用户名或密码错误");
    }

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

package servlet;

import 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域中共享的user对象
        User user = (User) request.getAttribute("user");

        if (user != null) {
            //打印提示信息
            //设置页面编码
            response.setContentType("text/html;charset=utf-8");
            //输出
            response.getWriter().write("登陆成功！" + user.getUsername() + "，欢迎您");
        }
    }

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

包、类层级结构

实现效果：

JavaEE 小项目：用户登录

项目需求

开发步骤

1. 创建项目，编写html页面，配置文件，导入jar包

2. 创建数据库环境

3. 创建包domain，创建类User

4. 创建包util，编写工具类JDBCUtils

5. 创建包dao，创建类UserDao，提供login方法

6. 创建包servlet，创建类LoginServlet

7. 编写FailServlet 和 SuccessServlet类

包、类层级结构

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