javaweb简单登录功能(视频学习总结)

一，需求

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
3，使用JdbcTemplate技术封装JDBC
4，登录成功后跳转到succeedServlet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

二，准备

1，我的项目结构预览

2，数据库配置文件 druid.properties

driverClassName = com.mysql.jdbc.Driver
url = jdbc:mysql:///javawebdemo
user = root
pwd = 36916280
# 初始化连接数量
initialSize = 5
# 最大连接数
maxActive = 10
# 最大等待时间
maxWait = 3000

3，创建数据库及表

CREATE DATABASE javawebdemo;
USE javawebdemo;
CREATE TABLE USER(
id INT PRIMARY KEY AUTO_INCREMENT,
username VARCHAR(20) UNIQUE,
password VARCHAR(20) NOT NULL
);

参见：https://blog.csdn.net/johnfht/article/details/104377177

4，编写登录页面 login.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>用户登录</title>
</head>
<body>
<h1>用户登录</h1>
<form action="" method="post">
    <p>用户名：<input type="text" name="username"></p>
    <p>密码：<input type="password" name="password"></p>
    <p><input type="submit" value="登录"></p>
</form>

</body>
</html>

三，后端代码

1，//用户的实体类 User.java

package com.domain;


//用户的实体类
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 + '\'' +
                '}';
    }
}

2，//JDBC工具类 JDBCUtils.java

package com.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
            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();
    }
}

4，//操作数据库中User表的类 UserDao.java

package com.dao;

import com.domain.User;
import com.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
    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>(User.class),
                    loginUser.getUsername(), loginUser.getPassword());
            return user;
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }
}

4，Junit单元测试 UserDaoTest.java

package com.test;

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

public class UserDaoTest {

    @Test
    public void loginTest(){
        User loginUser = new User();
        loginUser.setUsername("admin");
        loginUser.setPassword("123456");

        UserDao ud = new UserDao();
        User user = ud.login(loginUser);

        System.out.println(user);
    }
}

成功验证

四，界面控制

1，LoginServlet.java

package com.web.servlet;

import com.dao.UserDao;
import com.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 {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //1.设置编码
        request.setCharacterEncoding("utf-8");
        response.setContentType("text/html; charset=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);*/

        //2.获取所有请求参数
        Map<String, String[]> map = request.getParameterMap();
        //3.创建User对象
        User loginUser = new User();
        //3.2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 ud = new UserDao();
        User user = ud.login(loginUser);

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

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

2，LoginSucceesServlet.java

package com.web.servlet;

import com.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("/loginSucceesServlet")
public class LoginSucceesServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //设置编码
        request.setCharacterEncoding("utf-8");
        response.setContentType("text/html; charset=utf-8");

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

        if(user != null){
            //给页面写一句话输出
            response.getWriter().write("登录成功，欢迎您：" + user.getUsername());
        }
    }

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

3，LoginFailServlet.java

package com.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("/loginFailServlet")
public class LoginFailServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //设置编码
        request.setCharacterEncoding("utf-8");
        response.setContentType("text/html; charset=utf-8");

        //给页面写一句话输出
        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 {
        doPost(request, response);
    }
}

五，页面展示

1，登录首页

2，登录失败

3，登录成功

johnfht

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javaweb简单登录功能(视频学习总结)

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