druid是一个非常常用的数据库连接池，可以和jdbc template一起来使用
下面我们就模拟一个登录的场景

数据库建设

创建一个login数据库，并且创建一个user表包含id，username，password三个字段。
并且默认一个数据，做好数据准备工作

项目搭建

在IDEA中创建一个login模块，并在src目录中创建我们要用到的包
在包domain存放我们的用户类User对应数据库user表，设置成员变量一一对应user数据库表

package cn.wang.domain;

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;
    }
}

数据库连接池配置，在web文件夹下新建WEB-INF文件夹，把需要的jar包放到lib文件夹下，并加载到模块中
在src文件夹下存放druid配置文件 druid.properties文件，配置数据库信息

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

在util包中新建JDBCUtils数据库连接工具类

package cn.wang.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;

/**
 * Durid连接池使用
 */
public class JDBCUtils {
    
    
    private static DataSource ds;

    static {
    
    
        try {
    
    
            Properties pro = new Properties();
            InputStream is = JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties");
            pro.load(is);
             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;
    }

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

}

在包dao中新建UserDao对数据库进行操作，返回User对象

package cn.wang.dao;

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

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Test测试数据连接是否正确，在包test中创建UserDaoTest，并且进行执行，执行成功则我们的连接正常

package cn.wang.test;

import cn.wang.dao.UserDao;
import cn.wang.domain.User;
import org.junit.Test;



public class UserDaoTest {
    
    
    @Test
    public void testLogin() {
    
    
        User loginuser = new User();
        loginuser.setUsername("admin");
        loginuser.setPassword("123456");


        UserDao dao = new UserDao();
        User user = dao.login(loginuser);

        System.out.println(user);
    }
}

上面我们的内部处理已经完成，后面我们只需要将，web提交的数据进行上面流程并且进行登录判断，在新建servlet进行数据接受并调用上述的过程
在web目录下新建login.html文件，用于数据提交

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

在servlet包中创建LoginServlet用于接受表单数据

package cn.wang.web.servlet;

import cn.wang.dao.UserDao;
import cn.wang.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 {
    
    
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    
    
        this.doGet(request, response);

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    
    
        request.setCharacterEncoding("utf-8");
        System.out.println("doget");
        String username = request.getParameter("username");
        String password = request.getParameter("password");
        User loginUser = new User();
        loginUser.setUsername(username);
        loginUser.setPassword(password);
        UserDao dao = new UserDao();
        User user = dao.login(loginUser);
        if (user == null) {
    
    
            request.getRequestDispatcher("/failServlet").forward(request, response);
        } else {
    
    
            request.setAttribute("user", user);
            request.getRequestDispatcher("/successServlet").forward(request, response);
        }
    }
}

接收到表单的数据，执行dao中的逻辑，并在servlet中进行结果判断，有结果转到成功servlet处理，失败则转到另一个进行处理
失败

package cn.wang.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 {
    
    
        response.setContentType("text/html;charset=utf-8");
        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);
    }
}

成功

package cn.wang.web.servlet;

import cn.wang.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 {
    
    
        User user = (User) request.getAttribute("user");
        if (user != null) {
    
    
            response.setContentType("text/html;charset=utf-8");
            response.getWriter().write("登陆成功！"+user.getUsername()+",欢迎你");
        }
    }

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

在这里插入图片描述

代码地址

JavaWeb学习笔记（三）：使用druid连接池简易登录实例

数据库建设

项目搭建

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