Druid、mysql、jdbcTemplate和servlet实现简单的登陆验证（含源码）

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，login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

步骤：

创建项目，导入html页面，配置文件，jar包
创建数据库环境
创建类User
编写工具类JDBCUtils
创建类UserDao,提供login方法
编写LoginServlet类
编写FailServlet和SuccessServlet类
login.html中form表单的action路径的写法
----虚拟目录+Servlet的资源路径
BeanUtils工具类，简化数据封装

代码：

html页面、druid.properties配置文件内容、所需jar包

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

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

2.数据库语句

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
);

3.User类

package cn.ycl.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 + '\'' +
                '}';
    }
}

工具类JDBCUtils

package cn.ycl.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的工具类，使用Druid连接池 */
public class JDBCUtils {
    private static DataSource dataSource;
    static {
        try {
            //1.加载配置文件
            Properties pro = new Properties();
            InputStream is = JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties");
            pro.load(is);
            //2.初始化连接池对象
            dataSource = DruidDataSourceFactory.createDataSource(pro);
        } catch (IOException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    /** * 获取连接池对象 * @return */
    public static DataSource getDataSource(){
        return dataSource;
    }

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

UserDao类

package cn.ycl.dao;

import cn.ycl.domain.User;
import cn.ycl.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());
    /** * 登陆 * @param loginUser 用户名和密码 * @return User对象 */
    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 (DataAccessException e){
            e.printStackTrace();//记录日志
            return null;
        }
    }
}

LoginServlet类

package cn.ycl.servlet;

import cn.ycl.dao.UserDao;
import cn.ycl.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");
        Map<String,String[]> map = req.getParameterMap();
        //3.封装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){
            //登陆失败
            req.getRequestDispatcher("/failServlet").forward(req,resp);
        }else {
            //登陆成功
            //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);
    }
}

FailServlet和SuccessServlet类

package cn.ycl.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 {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //设置编码
        resp.setContentType("text/html;charset=utf-8");
        //打印文字
        resp.getWriter().write("登陆失败，用户名或密码错误" );
    }

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

package cn.ycl.servlet;

import cn.ycl.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 {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        User user =(User) req.getAttribute("user");
        if (user!=null){
            //设置编码
            resp.setContentType("text/html;charset=utf-8");
            //打印文字
            resp.getWriter().write("登陆成功，"+user.getUsername()+",欢迎你！" );
        }
    }

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