@【JSP+Servlet+JDBC】登录注册

**登录页面设计**
1，数据库设计与连接 user表，
2，前端设计
    登录页面 login.jsp
        yes --->success.jsp
        no ---->error.jsp
    注册页面 register.jsp
        yes --->success.jsp
        no ---->error.jsp
3,后端设计
    登录--->loginServlet.java
    注册--->rigsterServlet.java

效果展示

在这里插入图片描述
在这里插入图片描述

页面十分简单，主要是我为了学习http与后端以及数据库连接。

1，数据库连接

1.注册驱动：
Class.forName("com.mysql.jdbc.Driver");
2.获取连接

 Connection con = DriverManager.getConnection(url , username , password ) ;

3.创建一个preparedStatement

PreparedStatement pstmt = con.prepareStatement(sql) ;

4.执行SQL语句

ResultSet rs = stmt.executeQuery("SELECT * FROM ...") ;

JDBCUtils.java

package com.company.utils;

import java.io.IOException;
import java.io.InputStream;
import java.sql.*;
import java.util.Properties;


public class JDBCUtils {
    public JDBCUtils(){}
    private static String driverClass;
    private static String url;
    private static String username;
    private static String passward;
    private static Connection con;

    static {

        try {
            InputStream is = JDBCUtils.class.getClassLoader().getResourceAsStream("config.properties");
            Properties prop = new Properties();
            prop.load(is);

            driverClass = prop.getProperty("driverClass");
            url = prop.getProperty("url");
            username = prop.getProperty("username");
            passward = prop.getProperty("password");

            Class.forName(driverClass);


        } catch (IOException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }


    }
    public static Connection getConnection(){
        try {
            con = DriverManager.getConnection(url,username,passward);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return con;
    }
    public static void close(Connection con, Statement sta, ResultSet rs){
        if (con != null){
            try {
                con.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (sta != null){
            try {
                sta.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (rs != null){
            try {
                rs.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }

    }
    public static void close(Connection con, Statement sta){
        if (con != null){
            try {
                con.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (sta != null){
            try {
                sta.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}

配置文件config.properties
用来存放自己的数据库连接信息

driverClass = com.mysql.cj.jdbc.Driver
url = jdbc:mysql://localhost:3306/studentmanger
username = root
password = root

之后在UserDao类调用JDBCUtils方法就可以实现连接数据库，对数据库进行增删改查。

**

2.前端页面设计

**
login.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>登录</title>
</head>
<body>

<link rel="stylesheet" type="text/css" href="./homepage.css">
<div style="text-align: center">
    <form action="LoginServlet" method="post" id="loginform">
        账号：<input type="text" placeholder="手机号或邮箱" name="username"/><br>
        密码：<input type="password" placeholder="密码" name="passward"/><br>
        <input type="submit" class="inputButton" value="登录" />
        <a href="register.jsp">没有账号，点击注册</a>
    </form>
</div>


</body>
<script type="text/javascript" src="js/jquery-3.6.0.min.js"></script>
<script>

</script>
</html>

Register.jsp

<%--
  Created by IntelliJ IDEA.
  User: Yami
  Date: 2022/1/22
  Time: 21:05
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>注册页面</title>
</head>
<body>
<div style="text-align: center">
    <form action="RegisterServlet" method="post" id="registerform">
        账号：<input type="text" placeholder="手机号或邮箱" name="username"/><br>
        密码：<input type="password" placeholder="密码" name="passward"/><br>
        <input type="submit" class="inputButton" value="注册" />

    </form>
</div>
</body>
</html>

前端页面通过action="xxxServlet"连接后端，对登录和注册分别进行处理。

3.后端servlet

后端总共包括bean层、Dao层、servlet层。（因为功能比较简单，省略了service层）
在这里插入图片描述

bean层：定义User类
User.java

package com.company.bean;

public class User {
    private Integer id;
    private String username;
    private String password;

    public User() {
    }

    public User(Integer id, String username, String password) {
        this.id = id;
        this.username = username;
        this.password = password;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer 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 + '\'' +
                '}';
    }
}

Dao层：BaseDao+UserDao
BaseDao：一个接口，Basedao里写泛用性较强的抽象方法，比如数据库的增删改查，其他dao层接口继承basedao，对方法进行重写，可减少代码的重复，以追求高内聚低耦合。
BaseDao.java

package com.company.dao;

import java.util.List;

public BaseDao<E> {
    public boolean add(E e);

    public void delete(E e);

    public void update(E e);

    public boolean findbone(String username, String passward);

    public List<E> findall();
}

UserDao.java
继承BaesDao方法，增删改查方法（只写了部分会用到的，部分没写）

package com.company.dao;

import com.company.bean.User;
import com.company.utils.JDBCUtils;

import java.sql.*;
import java.util.ArrayList;
import java.util.List;

public class UserDao implements BaseDao<User>{
    JDBCUtils jdb = new JDBCUtils();

    @Override
    public boolean add(User user) {
        Connection con = null;
        PreparedStatement stat = null;
        int i = 0;
        try{
            con = JDBCUtils.getConnection();
            stat = con.prepareStatement("INSERT INTO user VALUES(?,?,?)");
            stat.setString(1,null);
            stat.setString(2, user.getUsername());
            stat.setString(3, user.getPassword());
            i = stat.executeUpdate();
            System.out.println(i);

        }catch (Exception e){
            e.printStackTrace();
        }finally {
            JDBCUtils.close(con, stat);
        }
        if(i>0){
            return true;
        }else {
            return false;
        }
    }

    @Override
    public void delete(User user) {
        Connection con = null;
        Statement stat = null;
        try{
            con = JDBCUtils.getConnection();
            stat = con.createStatement();
            String sql = "DELETE FROM user WHERE id='"+user.getId()+"'";
            stat.executeUpdate(sql);

        }catch (Exception e){
            e.printStackTrace();
        }finally {
            JDBCUtils.close(con, stat);
        }
    }

    @Override
    public void update(User o) {

    }

    @Override
    public boolean findbone(String username, String passward) {
        Connection con = null;
        PreparedStatement stat = null;
        ResultSet rs = null;
        boolean result = false;
        try {
            con = JDBCUtils.getConnection();
            stat = con.prepareStatement("SELECT *FROM user WHERE username = ? and passward = ?");
            stat.setString(1, username);
            stat.setString(2, passward);
            rs = stat.executeQuery();
            if (rs.next()) {
                result =  true;
            } else {
                result = false;
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            JDBCUtils.close(con, stat, rs);
        }
        return result;
    }

    @Override
    public List findall() {
        Connection con = null;
        Statement stat = null;
        ResultSet rs = null;
        ArrayList<User> list = new ArrayList<User>();
        try{
            con = JDBCUtils.getConnection();
            stat = con.createStatement();
            String sql = "SELECT *FROM user";
            rs = stat.executeQuery(sql);

            while(rs.next()){
                int id = rs.getInt("id");
                String name = rs.getString("name");
                User user = new User(id, name,null);
                list.add(user);
            }

        }catch (Exception e){
            e.printStackTrace();
        }finally {
            JDBCUtils.close(con, stat, rs);
        }
        return list;
    }
    }

servlet层
LoginServlet.java

package com.company.servlet;

import com.company.dao.UserDao;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;

@WebServlet(name = "LoginServlet", value = "/LoginServlet")
public class LoginServlet extends HttpServlet {
    UserDao userDao = new UserDao();

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

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String username = request.getParameter("username");
        String passward = request.getParameter("passward");
        System.out.println(passward);
        System.out.println(username);
        if(userDao.findbone(username,passward)){
            response.sendRedirect(request.getContextPath()+"/success.jsp");

        }else{
            response.sendRedirect(request.getContextPath()+"/error.jsp");
        }
    }
}

Register.java

package com.company.servlet;

import com.company.bean.User;
import com.company.dao.UserDao;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;

@WebServlet(name = "RegisterServlet", value = "/RegisterServlet")
public class RegisterServlet extends HttpServlet {
    UserDao userDao = new UserDao();
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request,response);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String username = request.getParameter("username");
        String passward = request.getParameter("passward");
        User user = new User(null,username,passward);
        if(userDao.add(user)){
            response.sendRedirect(request.getContextPath()+"/success.jsp");
            System.out.println("用户注册成功");
        }else{
            response.sendRedirect(request.getContextPath()+"/error.jsp");
            System.out.println("用户注册失败");
        }
    }
}

结束了，欢迎大家积极提出建议，一起讨论。
在这里插入图片描述
https://pan.baidu.com/s/12FoLk1iNO9N4VwveCnVRsA?pwd=ad3f
提取码：ad3f

# java # 数据库 # servlet # mysql
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