1. 在MySQL中创建一个用户表

在这里插入图片描述

2. 在IDEA中创建此项目

打开idea–>File–>New->Moudle–>JavaEnterprise–>勾选Web Application–>项目命名为logindemo
在这里插入图片描述

3. 对项目进行分层

在src目录下创建如下包，用于分层。
domain：实体类；servlet：控制层；dao：接口层；service：服务层；util：工具层；test：测试层
同时在WEB-INF目录下创建一个lib目录，先复制mysql-connector-java-5.1.6.jar包，并添加为Module jar包，用于连接数据库。

4. 测试数据库是否连接成功

在domain 实体层下创建实体类 Users
注意：实体类的名字尽量与数据库中的表名一致，此项目中都名为Users

package com.zz.domain;
import java.io.Serializable;

//实体层:用户表
//Serializable接口是启用其序列化功能的接口
public class Users implements Serializable {
    private int id;
    private String name;
    private String gender;
    private String password;
    private String email;
    private String birthday;

    public Users() {
    }

    public Users(int id, String name, String gender, String password, String email, String birthday) {
        this.id = id;
        this.name = name;
        this.gender = gender;
        this.password = password;
        this.email = email;
        this.birthday = birthday;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String getBirthday() {
        return birthday;
    }

    public void setBirthday(String birthday) {
        this.birthday = birthday;
    }

    @Override
    public String toString() {
        return "Users{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", gender='" + gender + '\'' +
                ", password='" + password + '\'' +
                ", email='" + email + '\'' +
                ", birthday='" + birthday + '\'' +
                '}';
    }
}

在Util 工具层下引入一个JDBC工具类，名为DBUtils, DBUtils中封装了对JDBC的操作

package com.zz.util;

import java.io.InputStream;
import java.sql.*;
import java.util.List;
import java.util.Properties;
import javax.sql.DataSource;
import org.apache.commons.dbcp2.BasicDataSourceFactory;

//DBUtils封装了对JDBC的操作
public class DBUtils {
    //访问数据库的小帮手
    public static PreparedStatement pstm;
    // 数据库连接池封装对象
    public static DataSource dataSource;

    // 操作属性文件对象
    public static Properties properties = new Properties();
    //完成类中静态属性初始化，并且多次访问时，只有一次访问才会执行此静态块，而且只执行一次
    static {
        //让is输入流对象只想src目录下的jdbc.properties
        InputStream is = DBUtils.class.getClassLoader().getResourceAsStream(
                "jdbc.properties");

        try {
            //加载属性文件到properties对象中
            properties.load(is);
            //数据库连接加载配置文件，完成访问数据库的所有配置
            dataSource = BasicDataSourceFactory.createDataSource(properties);

        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    //保证线程安全的数据库访问，一个线程只绑定一个链接对象，多次访问时同一个连接对象
    private static ThreadLocal<Connection> tl = new ThreadLocal<Connection>();
    //打开数据库连接
    public static Connection getConnection() {

        Connection conn = tl.get();// 从当前线程上获得链接
        try {
            if (conn == null || conn.isClosed() ) {
                //从连接池中获取连接对象
                conn = dataSource.getConnection();
                // 把连接绑定到当前线程上
                tl.set(conn);
            }
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return conn;
    }

    //关闭所有数据库访问对象
    public static void closeAll(Connection con, PreparedStatement pstm,
                                ResultSet rs) {

        try {
            if (rs != null)
                rs.close();
            if (pstm != null)
                pstm.close();
            if (con != null && !con.isClosed())
                con.close();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    //关闭所有数据库访问对象
    public static void closeAll() {

        try {

            if (pstm != null)
                pstm.close();
            if (DBUtils.getConnection() != null && !DBUtils.getConnection().isClosed())
                DBUtils.getConnection().close();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    // 所有的增删改的方法
    public static int myExecuteUpdate(String sql, List list) throws Exception {

        //添加第二个参数的意义是为了获得新增记录的主键。
        pstm = getConnection().prepareStatement(sql,Statement.RETURN_GENERATED_KEYS);
        if (list != null) {
            for (int i = 0; i < list.size(); i++) {
                pstm.setObject(i + 1, list.get(i));
            }
        }
        return pstm.executeUpdate();
    }

    // 所有的查询的方法
    public static ResultSet myExecuteQuery(String sql, List list) {

        try {
            //第二个参数的意思，执行更新语句后可以获得主键
            pstm = getConnection().prepareStatement(sql);
            if (list != null) {
                for (int i = 0; i < list.size(); i++) {
                    pstm.setObject(i + 1, list.get(i));
                }
            }
            return pstm.executeQuery();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return null;
    }

    public static void startTransaction() {
        Connection conn = getConnection();
        try {
            conn.setAutoCommit(false);
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public static void commit() {
        Connection conn = getConnection();
        try {
            conn.commit();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public static void rollback() {
        Connection conn = getConnection();
        try {
            conn.rollback();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public static void release() {
        Connection conn = getConnection();
        try {
            conn.close();
            tl.remove();// 与线程池有关，解除关系
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
    public static void endTransaction() {
        Connection conn = getConnection();
        try {
            conn.setAutoCommit(true);
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

在lib 目录下按照之前的方法导入commons-dbcp2-2.7.0.jar、commons-logging-1.2.jar、commons-pool2-2.7.0.jar三个jar包，同样以模块jar包使用，至此lib目录下，有如下四个jar包
在src目录下创建文件 jdbc.properties

driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/xbky?useUnicode=true&characterEncoding=UTF-8
username=root
password=123456
initialSize=20

在test 测试层创建Test类
在此，先测试连接数据库是否成功

package com.zz.test;

import com.zz.util.DBUtils;

import java.sql.Connection;

public class Test {
    public static void main(String[] args) {
        Connection conn;

        try {
            conn = DBUtils.getConnection();
            if(conn!=null){
                System.out.println("sql连接成功！");
            }else{
                System.out.println("sql连接失败！");
            }

        }catch (Exception ex){
            ex.printStackTrace();
        }
    }
}

至此，项目包结构如下
在这里插入图片描述

运行结果如下，显示连接成功
在这里插入图片描述

5. 编写接口、实现登录和注册功能

在dao 接口层编写用户的业务逻辑接口UserDao
有登录、注册以及根据用户编号查询用户的方法

package com.zz.dao;

import com.zz.domain.Users;

//用户的业务逻辑接口
public interface UsersDao {

    //用户登录
    public Users login(String name, String password);

    //用户注册
    public Users reg(Users users);


    //根据用户编号查询用户
    public Users queryUserByid(int id);
}

编写接口的实现类UsersDaoImpl

package com.zz.dao.impl;

import com.zz.dao.UsersDao;
import com.zz.domain.Users;
import com.zz.util.DBUtils;

import java.sql.Connection;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;

//接口UsersDao的实现类，实现接口的所有方法
public class UsersDaoImpl implements UsersDao {


    //用户登录
    @Override
    public Users login(String name, String password) {
        Connection conn;  // 连接对象
        ResultSet rs;  //数据集

        List args = new ArrayList(); //参数集合
        String sql = "select * from users where name=? and password=?";  //？占位符
        Users loginUser = null;  //用户对象


        try {
            conn = DBUtils.getConnection();
            args.add(name);
            args.add(password);
            rs = DBUtils.myExecuteQuery(sql, args);  //传进去返回一个数据集
            if (rs.next()) { //如果有下条记录就说明就登录成功了。用户资料返回
                loginUser = new Users();
                loginUser.setId(rs.getInt("id"));
                loginUser.setName(rs.getString("name"));
                loginUser.setPassword(rs.getString("password"));
                loginUser.setGender(rs.getString("gender"));
                loginUser.setEmail(rs.getString("email"));
                loginUser.setBirthday(rs.getString("birthday"));
            }

            return loginUser;
        } catch (Exception ex) {
            ex.printStackTrace();
            return null;
        }

    }

    @Override
    public Users reg(Users users) {
        Connection conn; //连接对象
        List args = new ArrayList();
        String sql = "insert into users (name,password,gender,email,birthday) values (?,?,?,?,?)";
        Users regUser = null;
        int result;
        try {
            conn = DBUtils.getConnection();
            DBUtils.startTransaction();//开启事务
            args.add(users.getName());
            args.add(users.getPassword());
            args.add(users.getGender());
            args.add(users.getEmail());
            args.add(users.getBirthday());
            result = DBUtils.myExecuteUpdate(sql, args);

            if (result > 0) { //说明注册成功了。用户资料返回
                //获得新生成的用户的编号。
                //问题的焦点是你如何获得新添加用户的主键呢？
                ResultSet temp = DBUtils.pstm.getGeneratedKeys();
                temp.next();
                int id = temp.getInt(1);

                regUser = queryUserByid(id);
            }
            DBUtils.commit(); //提交事务
            DBUtils.endTransaction();

            return regUser;
        } catch (Exception ex) {
            ex.printStackTrace();
            DBUtils.rollback(); //回滚
            DBUtils.endTransaction(); //关闭事务
            return null;
        }
    }

    @Override
    public Users queryUserByid(int id) {
        Connection conn; //连接对象
        ResultSet rs; //数据集
        List args = new ArrayList();
        String sql = "select * from users where id=?";
        Users user = null;
        try{
            conn = DBUtils.getConnection();
            args.add(id);

            rs = DBUtils.myExecuteQuery(sql,args);
            if(rs.next()){ //说明就登录成功了。用户资料返回
                user = new Users();
                user.setId(rs.getInt("id"));
                user.setName(rs.getString("name"));
                user.setPassword(rs.getString("password"));
                user.setGender(rs.getString("gender"));
                user.setEmail(rs.getString("email"));
                user.setBirthday(rs.getString("birthday"));
            }
            return user;
        }catch(Exception ex){
            ex.printStackTrace();
            return null;
        }
    }
}

在测试层编写测试类Test
测试用户的登录效果，和注册效果

package com.zz.test;

import com.zz.dao.UsersDao;
import com.zz.dao.impl.UsersDaoImpl;
import com.zz.domain.Users;
import com.zz.util.DBUtils;

import java.sql.Connection;

public class Test {
    public static void main(String[] args) {

       /* Connection conn;

        try {
            conn = DBUtils.getConnection();
            if(conn!=null){
                System.out.println("sql连接成功！");
            }else{
                System.out.println("sql连接失败！");
            }

        }catch (Exception ex){
            ex.printStackTrace();
        }*/

        //测试用户登录的效果。

        Users loginUser = null;
        UsersDao usersDao = new UsersDaoImpl();

        loginUser = usersDao.login("张某","123456");

        if(loginUser!=null){
            System.out.println("登录成功！");
        }else{
            System.out.println("登录失败！");
        }

       /*
        // 测试用户注册的效果
        Users regUser = new Users();
        regUser.setName("王某");
        regUser.setGender("男");
        regUser.setPassword("654321");
        regUser.setEmail("[email protected]");
        regUser.setBirthday("1998-11-10");
        UsersDao usersDao = new UsersDaoImpl();
        regUser = usersDao.req(regUser);
        System.out.println(regUser);

*/

    }
}

6. 编写service层

跟dao层类似

编写接口UsersService

package com.zz.service;

import com.zz.domain.Users;

public interface UsersService {


        //用户登录
        public Users login(String name, String password);

        //用户注册
        public Users reg(Users users);


        //根据用户编号查询用户
        public Users queryUserByid(int id);
    }

编写接口的实现类 UsersServiceImpl

package com.zz.service.impl;

import com.zz.dao.UsersDao;
import com.zz.dao.impl.UsersDaoImpl;
import com.zz.domain.Users;
import com.zz.service.UsersService;

public class UsersServieImpl implements UsersService {

    private UsersDao usersDao = new UsersDaoImpl();

    @Override
    public Users login(String username, String password) {
        return usersDao.login(username,password);
    }

    @Override
    public Users reg(Users users) {
        return usersDao.reg(users);
    }

    @Override
    public Users queryUserByid(int id) {
        return usersDao.queryUserByid(id);
    }
}

7. 编写servlet层

package com.zz.servlet;

import com.zz.domain.Users;
import com.zz.service.UsersService;
import com.zz.service.impl.UsersServieImpl;
import com.zz.service.impl.UsersServieImpl;

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(name = "UsersServlet",value="UsersServlet")
public class UsersServlet extends HttpServlet {

    private String action ;

    private UsersService usersService = new UsersServieImpl();

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
         if(request.getParameter("action")!=null){
             this.action = request.getParameter("action");
             switch(this.action){
                 case "login":
                     login(request,response);
                     break;
                 case "reg":
                     reg(request,response);
                     break;
             }
         }
    }

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

    //执行登录动作
    private void login(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException{
        Users loginUser = null;
        loginUser = usersService.login(request.getParameter("name"),request.getParameter("password"));
        if(loginUser!=null){
            System.out.println("登录成功！");
            //把登录成功的用户保存到session中
            request.getSession().setAttribute("loginUser",loginUser);
            response.sendRedirect(request.getContextPath()+"/main.jsp");
        }else{
            System.out.println("登录失败！");
            response.sendRedirect(request.getContextPath()+"/login_failure.jsp");
        }
    }

    //执行注册
    private void reg(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException{
        Users user = new Users();
        user.setName(request.getParameter("name"));
        user.setPassword(request.getParameter("password"));
        user.setGender(request.getParameter("gender"));
        user.setEmail(request.getParameter("email"));
        user.setBirthday(request.getParameter("birthday"));

        Users regUser = null;
        regUser = usersService.reg(user);
        if(regUser!=null){
            System.out.println("注册成功！");
            System.out.println(regUser);
            //页面跳转到登录页面。
            response.sendRedirect(request.getContextPath()+"/login.jsp");

        }else{
            System.out.println("注册失败！");

        }
    }
}

8. 编写filter过滤器

添加一个过滤器，防止中文乱码

package com.zz.filter;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.annotation.WebInitParam;
import java.io.IOException;

//规定，乌龟的屁股规定。
@WebFilter(description = "EncodingFilter",value="/*",initParams ={@WebInitParam(name="encoding",value="utf-8")}) // 凡是过滤器一般都是 /* ,过滤所有的请求
public class EncodingFilter implements Filter {

    private String encoding;

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
         this.encoding = filterConfig.getInitParameter("encoding");
    }

    //过滤器过滤的是请求，什么样的请求呢？各种各样请求，只有是请求，就被过滤以下。能理解吗？
    //过滤器在过滤器请求的时候，一定会执行doFilter这个方法
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        //请求使用utf-8
        servletRequest.setCharacterEncoding(this.encoding);
        //响应也使用utf-8
        servletResponse.setCharacterEncoding(this.encoding);
        //不会有中文乱码
        filterChain.doFilter(servletRequest,servletResponse); //千万不要忘了写，过滤器链条，继续向后过滤
    }

    @Override
    public void destroy() {
    }
}

9. 编写JSP页面

登录页面 login.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>用户登录</title>
    <style>
        #regDiv {

            /*div水平居中*/
            margin: 0px auto;
            width: 400px;
            height: 70px;

            border: 1px solid #ccc;

            padding: 10px;
        }

        h1 {
            text-align: center;

        }

        input {
            width: 280px;
        }

        .label {
            width: 30%;
        }

        .controller {
            width: 70%;
        }

        table {
            border-collapse: collapse;
            border-spacing: 0px 0px;
            height: auto;
        }
    </style>
</head>
<body>
<h1>用户登录</h1>


<div id="regDiv">

    <form action="${pageContext.request.contextPath}/UsersServlet?action=login" method="post">

        <table>
            <tr>
                <td class="label">用户名:</td>
                <td class="controller"><input type="text" name="name"></td>
            </tr>
            <tr>
                <td class="label">密码:</td>
                <td class="controller"><input type="password" name="password"></td>
            </tr>
            <tr>
            <%--colspan=“2”是指将2列合并，合并之后要把合并的那个单元格删除掉，才能体现出效果
                text-align指这个div块内的文本居中--%>
                <td colspan="2" style="text-align: center">
                    <input type="submit" style="width:60px" value="登录">
                </td>
            </tr>
        </table>
    </form>
</div>

</body>
</html>

注册页面 reg.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>用户注册</title>
    <style>
        #regDiv {

            /*div水平居中*/
            margin: 0px auto;
            width: 400px;
            height: 160px;

            border: 1px solid #ccc;

            padding: 10px;
        }

        h1 {
            text-align: center;

        }

        input {
            width: 280px;
        }

        .label {
            width: 30%;
        }

        .controller {
            width: 70%;
        }

        table {
            border-collapse: collapse;
            border-spacing: 0px 0px;
            height: auto;
        }
    </style>
</head>
<body>
<h1>用户注册</h1>


<div id="regDiv">

    <form action="${pageContext.request.contextPath}/UsersServlet?action=reg" method="post">

        <table>
            <tr>
                <td class="label">用户名:</td>
                <td class="controller"><input type="text" name="name"></td>
            </tr>
            <tr>
                <td class="label">密码:</td>
                <td class="controller"><input type="password" name="password"></td>
            </tr>
            <tr>
                <td class="label">确认密码:</td>
                <td class="controller"><input type="password" name="confirmpass"></td>
            </tr>
            <tr>
                <td class="label">性别:</td>
                <td class="controller">
                    <input type="radio" style="width:20px" name="gender" value="男" checked/>男
                    <input type="radio" style="width:20px"  name="gender" value="女" />女
                </td>
            </tr>
            <tr>
                <td class="label">电子邮箱:</td>
                <td class="controller"><input type="text" name="email" value=""/></td>
            </tr>
            <tr>
                <td class="label">出生日期:</td>
                <td class="controller"><input type="date" name="birthday" value=""/></td>
            </tr>

            <tr>
                <td colspan="2" style="text-align: center">
                    <input type="submit" style="width:60px" value="注册">
                </td>
            </tr>
        </table>
    </form>
</div>

</body>
</html>

主页面 main.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title></title>
</head>
<body>
<h1>系统主页面</h1>
<hr>
<div id="main">
    欢迎您：${sessionScope.loginUser.name}<br>
</div>
</body>
</html>

登录失败页面 login_failure.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
<h1>登录失败</h1>
<hr>
<a href="login.jsp">返回</a>
</body>
</html>