[JavaScript知识库] 2.servlet实现登录功能

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[JavaScript知识库]2.servlet实现登录功能

在该案例中，通过servlet实现了用户登录的功能。主要涉及前端页面请求数据，servlet程序处理请求，业务逻辑层调用相关的dao层，在数据库提取数据并return给service层进行验证，将验证结果经过servlet返还给前端页面，进行显示。

创建admin数据表

CREATE TABLE `admin` (
  `username` VARCHAR(20) NOT NULL,
  `password` VARCHAR(20) NOT NULL,
  `phone` VARCHAR(11) NOT NULL,
  `Address` VARCHAR(20) NOT NULL,
  PRIMARY KEY (`username`)
) ENGINE=INNODB DEFAULT CHARSET=utf8mb3

创建前端页面

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>登录页面</title>
</head>
<body>
    <form action="/servlet_war_exploded/login" 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>

创建Admin.java实体类

package com.ws.servletProject.entity;

public class Admin {
    private String username;
    private String password;
    private String phone;
    private String Address;

    public Admin() {
    }

    public Admin(String username, String password, String phone, String address) {
        this.username = username;
        this.password = password;
        this.phone = phone;
        Address = address;
    }

    @Override
    public String toString() {
        return "Admin{" +
                "username='" + username + '\'' +
                ", password='" + password + '\'' +
                ", phone='" + phone + '\'' +
                ", Address='" + Address + '\'' +
                '}';
    }

    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;
    }

    public String getPhone() {
        return phone;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }

    public String getAddress() {
        return Address;
    }

    public void setAddress(String address) {
        Address = address;
    }
}

创建配置文件database.properties

通过该文件提供数据库的一些信息的配置，然后会通过DbUtils.java程序来加载该文件，连接数据库

#key=value
driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/practice?useUnicode=true&characterEncoding=utf-8&userSSL=false&serverTimezone=GMT%2B8
#url=jdbc:mysql://localhost:3306/girls
username=root
password=123
#initial connection Size
initialSize=10
#min idle connecton size
minIdle=5
#max active connection size
maxActive=20
#max wait time (5000 mil seconds)
maxWait=5000

创建工具类DbUtils.java

该程序主要通过创建数据库连接池（德鲁伊连接池），提供连接，事务控制以及释放连接资源

package com.ws.servletProject.utils;

import com.alibaba.druid.pool.DruidDataSource;
import com.alibaba.druid.pool.DruidDataSourceFactory;

import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;
@SuppressWarnings({"all"})
public class DbUtils {
    //创建连接池
    private static DruidDataSource ds;
    private static final ThreadLocal<Connection> THREAD_LOCAL = new ThreadLocal<>();//控制连接的线程

    //静态代码块，初始配置内容
    static {
        Properties properties = new Properties();
        InputStream inputStream = DbUtils.class.getResourceAsStream("/database.properties");//获取一个字节输入流
        try {
            properties.load(inputStream);
            //创建连接池
            ds = (DruidDataSource) DruidDataSourceFactory.createDataSource(properties);
        } catch (IOException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }


    //获得连接
    public static Connection getConnection(){
        Connection connection = THREAD_LOCAL.get();//获取连接
        try {
            if (connection == null){
                connection = ds.getConnection();//在连接池中拿取一个connection
                THREAD_LOCAL.set(connection);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return connection;
    }
    //事务控制
    //开启事务
    public static void begin(){
        Connection connection = null;
        try {
            connection = getConnection();
            connection.setAutoCommit(false);
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
    //提交事务
    public static void commit(){
        Connection connection = null;
        try {
            connection = getConnection();
            connection.commit();
        } catch (SQLException e) {
            e.printStackTrace();
        }finally {
            closeAll(connection,null,null);//提交事务时候释放连接，connection，statement，resoultset
        }
    }
    //事务回滚
    public static void rollback(){
        Connection connection = null;
        try {
            connection = getConnection();
            connection.rollback();
        } catch (SQLException e) {
            e.printStackTrace();
        }finally {
            closeAll(connection,null,null);//提交事务时候释放连接，connection，statement，resultset
        }
    }

    //释放资源
    public static void closeAll(Connection connection, Statement statement, ResultSet resultSet){
        try {
            if (resultSet != null){
                resultSet.close();
            }
            if (statement != null){
                statement.close();
            }
            if (connection != null){
                connection.close();
                THREAD_LOCAL.remove();//将连接从线程对象中移除
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

创建DAO层相关代码

创建AdminDao.java接口

该接口规定操作数据库的一些方法

package com.ws.servletProject.dao;

import com.ws.servletProject.entity.Admin;

import java.util.List;

public interface AdminDao {
    public int insert(Admin admin);
    public int delete(String username);
    public int update(Admin admin);

    public Admin select(String username);
    public List<Admin> selectAll();
}

创建AdminDaoImpl.java实现接口类

通过该程序可以对数据库实现具体的SQL语句操作，实质上也算是工具类

package com.ws.servletProject.dao.impl;

import com.ws.servletProject.dao.AdminDao;
import com.ws.servletProject.entity.Admin;
import com.ws.servletProject.utils.DbUtils;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanHandler;
import org.apache.commons.dbutils.handlers.BeanListHandler;

import java.sql.SQLException;
import java.util.List;

public class AdminDaoImpl implements AdminDao {
    private QueryRunner queryRunner = new QueryRunner();
    @Override
    public int insert(Admin admin) {
        return 0;
    }

    @Override
    public int delete(String username) {
        return 0;
    }

    @Override
    public int update(Admin admin) {
        return 0;
    }

    @Override
    public Admin select(String username) {
        try {
            Admin admin = queryRunner.query(DbUtils.getConnection(),"select * from admin where username=?;",new BeanHandler<Admin>(Admin.class),username);
            return admin;
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return null;
    }

    @Override
    public List<Admin> selectAll() {
        try {
            List<Admin> query = queryRunner.query(DbUtils.getConnection(), "select * from admin;", new BeanListHandler<Admin>(Admin.class));
            return query;
        } catch (SQLException e) {
            e.printStackTrace();
        }

        return null;
    }
}

创建业务逻辑层相关代码（service）

创建AdminService.java接口

该程序主要是用来规定一些业务逻辑的方法

package com.ws.servletProject.service;

import com.ws.servletProject.entity.Admin;

import java.util.List;

public interface AdminService {
    public Admin login(String username, String password);//通过servlet传入的 username,password 调用AdminDao对象进行数据提取，并且验证
    public List<Admin> showAllAdmin();//展示所有用户的方法
}

创建AdminServiceImpl.java实现类

package com.ws.servletProject.service.impl;

import com.ws.servletProject.dao.AdminDao;
import com.ws.servletProject.dao.impl.AdminDaoImpl;
import com.ws.servletProject.entity.Admin;
import com.ws.servletProject.service.AdminService;
import com.ws.servletProject.utils.DbUtils;

import java.util.List;

public class AdminServiceImpl implements AdminService {
    private AdminDao adminDao = new AdminDaoImpl();
    @Override
    public Admin login(String username, String password) {
        Admin result = null;//创建一个Admin类，用来返回数据
        try {
            DbUtils.begin();//开启事务
            Admin admin = adminDao.select(username);//执行查询
            if (admin != null){//进行判断
                if (admin.getPassword().equals(password)){
                    result = admin;//赋值
                }
            }
            DbUtils.commit();//提交事务
        } catch (Exception e) {
            DbUtils.rollback();//如果出现异常，进行事务的回滚
            e.printStackTrace();
        }
        return result;
    }

    @Override
    public List<Admin> showAllAdmin() {
        List<Admin> admins = null;
        try {
            DbUtils.begin();
            admins = adminDao.selectAll();
            DbUtils.commit();
        } catch (Exception e) {
            DbUtils.rollback();
            e.printStackTrace();
        }
        return admins;
    }
}

创建LoginServlet.java

package com.ws.servletProject.servlet;

import com.ws.servletProject.entity.Admin;
import com.ws.servletProject.service.AdminService;
import com.ws.servletProject.service.impl.AdminServiceImpl;
import com.ws.servlet_.HttpsServlet;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
@WebServlet(value = "/login")
public class LoginServlet extends HttpsServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.setCharacterEncoding("UTF-8");
        resp.setContentType("text/html;charset=UTF-8");
        //接收参数
        String username = req.getParameter("username");
        String password = req.getParameter("password");
        //调用业务逻辑进行验证
        AdminService adminService = new AdminServiceImpl();
        Admin admin = adminService.login(username, password);
        //验证用户是否存在之后，对返回的结果进行处理
        //响应给客户端一个结果
        PrintWriter writer = resp.getWriter();
        if (admin != null){
            writer.println("<html>");
            writer.println("<head>");
            writer.println("<meta charset='UTF-8'>");
            writer.println("<title>结果</title>");
            writer.println("</head>");
            writer.println("<body>");
            writer.println("<h1>登录成功！</h1>");
            writer.println("</body>");
            writer.println("</html>");
        }else {
            writer.println("<html>");
            writer.println("<head>");
            writer.println("<meta charset='UTF-8'>");
            writer.println("<title>结果</title>");
            writer.println("</head>");
            writer.println("<body>");
            writer.println("<h1>登录失败！</h1>");
            writer.println("</body>");
            writer.println("</html>");
        }
    }

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

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