【JavaWeb学习笔记】19 - 网购家居项目开发（上）

一、项目开发流程

程序框架图

项目具体分层方案

MVC

1、说明是MVC

MVC全称: Mode模型、View视图、Controller控制器。

MVC最早出现在JavaEE三层中的Web层，它可以有效的指导WEB层的代码如何有效分离，单独工作。

View视图:只负责数据和界面的显示，不接受任何与显示数据无关的代码，便于程序员和美工的分工(Vue/JSP/Thymeleaf/HTML)

Controller控制器:只负责接收请求，调用业务层的代码处理请求，然后派发页面，是一个"调度者"的角色(Servlet)

Model模型:将与业务逻辑相关的数据封装为具体的JavaBean类，其中不掺杂任何与数据处理相关的代码(JavaBean/Domain/Pojo)

2、MVC是一种思想

MVC的理念是将软件代码拆分成为组件，单独开发，组合使用(目的还是为了解耦合) ,也有很多落地的框架比如SpringMVC

二、实现1 正确加载静态页面

前端人员给的静态页面

三、实现功能02 会员注册前端JS校验

1.验证用户名:必须字母，数字下划线组成，并且长度为6到10位 => JQuery + 正则表达式

2.验证密码:必须由字母，数字下划线组成，并且长度为6到10位

3.邮箱格式验证:常规验证即可

4.验证码:后面实现

    <script type="text/javascript" src = "../../script/jquery-3.6.0.min.js"></script>
    <script>
        $(function () {//页面加载完成后执行function

            //绑定点击事件
            $("#sub-btn").click(function (){

                //获取输入的用户名 => 自己看前端给的页面
                var $userName = $("#username").val();
                // alert("usernameVal = " + $userName)
                //使用正则表达式进行验证
                var usernamePattern = /^\w{6,10}$/;
                if(!usernamePattern.test($userName)){
                    //查看前端给的代码是否有错误提示信息
                    // <span class="errorMsg"
                          // style="float: right; font-weight: bold; font-size: 20pt; margin-left: 10px;"></span>
                    //jquery的属性过滤器
                    $("span[class = 'errorMsg']").text("用户格式不对 需要6-10字符");
                    return false;//不提交 需要返回false 不返回false会导致页面跳转
                }
                var password = $("#password").val();
                var passwordPattern = /^\w{6,10}$/;
                if(!passwordPattern.test(password)){
                    //jquery的基本过滤器
                    $("span.errorMsg").text("密码格式不对 需要6-10字符");
                    return false;
                }
                //验证两次密码是否正确
                var repwd = $("#repwd").val();
                if(repwd != password){
                    $("span.errorMsg").text("输入的两次密码不同");
                    return false;
                }
                var email = $("#email").val();
                var emailPattern = /^[\w-]+@([a-zA-Z]+\.)+[a-zA-Z]+$/;
                if(!emailPattern.test(email)){
                    $("span[class = 'errorMsg']").text("电子邮件格式不对");
                    return false;
                }
                //到这里就全部过关 => 我们暂时不提交
                $("span.errorMsg").text("验证通过");
                return false;
            })
        })
    </script>

四、实现功能03 - 会员注册后端

导入mhl使用的BasicDAO以及JDBCbyDruid 测试是否成功

BasicDAO

package com.yinhai.furns.dao;


import com.yinhai.furns.utils.JDBCUtilsByDruid;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanHandler;
import org.apache.commons.dbutils.handlers.BeanListHandler;
import org.apache.commons.dbutils.handlers.ScalarHandler;

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

/**
 * @author 韩顺平
 * @version 1.0
 * 开发BasicDAO , 是其他DAO的父类
 */
public class BasicDAO<T> { //泛型指定具体类型

    private QueryRunner qr =  new QueryRunner();

    //开发通用的dml方法, 针对任意的表
    public int update(String sql, Object... parameters) {

        Connection connection = null;

        try {
            //这里从数据库连接池获取connection
            //老师说明: 每次从连接池中取出Connection , 不能保证是同一个
            //1.我们目前已经是从当前线程关联的ThreadLocal获取的connection
            //2.所以我们可以保证是同一个连接(在同一个线程/同一个请求)
            connection = JDBCUtilsByDruid.getConnection();
            int update = qr.update(connection, sql, parameters);
            return  update;
        } catch (SQLException e) {
           throw  new RuntimeException(e); //将编译异常->运行异常 ,抛出
        }

    }

    //返回多个对象(即查询的结果是多行), 针对任意表

    /**
     *
     * @param sql sql 语句，可以有 ?
     * @param clazz 传入一个类的Class对象 比如 Actor.class
     * @param parameters 传入 ? 的具体的值，可以是多个
     * @return 根据Actor.class 返回对应的 ArrayList 集合
     */
    public List<T> queryMulti(String sql, Class<T> clazz, Object... parameters) {

        Connection connection = null;
        try {
            connection = JDBCUtilsByDruid.getConnection();
            return qr.query(connection, sql, new BeanListHandler<T>(clazz), parameters);

        } catch (SQLException e) {
            throw  new RuntimeException(e); //将编译异常->运行异常 ,抛出
        }

    }

    //查询单行结果 的通用方法
    public T querySingle(String sql, Class<T> clazz, Object... parameters) {

        Connection connection = null;
        try {
            connection = JDBCUtilsByDruid.getConnection();
            return  qr.query(connection, sql, new BeanHandler<T>(clazz), parameters);

        } catch (SQLException e) {
            throw  new RuntimeException(e); //将编译异常->运行异常 ,抛出
        }
    }

    //查询单行单列的方法,即返回单值的方法

    public Object queryScalar(String sql, Object... parameters) {

        Connection connection = null;
        try {
            connection = JDBCUtilsByDruid.getConnection();
            return  qr.query(connection, sql, new ScalarHandler(), parameters);

        } catch (SQLException e) {
            throw  new RuntimeException(e); //将编译异常->运行异常 ,抛出
        } 
    }

}

JDBC工具类

package com.yinhai.furns.utils;

import com.alibaba.druid.pool.DruidDataSourceFactory;

import javax.sql.DataSource;
import java.io.FileInputStream;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;

/**
 * @author 韩顺平
 * @version 1.0
 * 基于druid数据库连接池的工具类
 */
public class JDBCUtilsByDruid {

    private static DataSource ds;
    //定义属性ThreadLocal, 这里存放一个Connection
    private static ThreadLocal<Connection> threadLocalConn =
            new ThreadLocal<>();

    //在静态代码块完成 ds初始化
    static {
        Properties properties = new Properties();
        try {
            //因为我们是web项目，他的工作目录在out, 文件的加载，需要使用类加载器
            //找到我们的工作目录
            properties.load(JDBCUtilsByDruid.class.getClassLoader()
                    .getResourceAsStream("druid.properties"));
            //properties.load(new FileInputStream("src\\druid.properties"));
            ds = DruidDataSourceFactory.createDataSource(properties);
        } catch (Exception e) {
            e.printStackTrace();
        }

    }

    //编写getConnection方法
    //public static Connection getConnection() throws SQLException {
    //    return ds.getConnection();
    //}

    /**
     * 从ThreadLocal获取connection, 从而保证在同一个线程中，
     * 获取的是同一个Connection
     * @return
     * @throws SQLException
     */
    public static Connection getConnection()  {

        Connection connection = threadLocalConn.get();
        if (connection == null) {//说明当前的threadLocalConn没有连接
            //就从数据库连接池中,取出一个连接放入, threadLocalConn
            try {
                connection = ds.getConnection();
                //将连接设置为手动提交, 即不要自动提交
                connection.setAutoCommit(false);
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
            threadLocalConn.set(connection);

        }
        return connection;
    }

    /**
     * 提交事务, java基础 mysql事务+线程+过滤器机制+ThreadLocal
     */
    public static  void commit() {

        Connection connection = threadLocalConn.get();
        if(connection != null) {//确保该连接是有效

            try {
                connection.commit();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            } finally {
                try {
                    connection.close();//关闭连接
                } catch (SQLException throwables) {
                    throwables.printStackTrace();
                }
            }
        }

        //老师说明
        //1. 当提交后，需要把connection从 threadLocalConn 清除掉
        //2. 不然，会造成 threadLocalConn 长时间持有该连接, 会影响效率
        //3. 也因为我们Tomcat底层使用的是线程池技术
        threadLocalConn.remove();

    }

    /**
     * 老师说明:  所谓回滚，是回滚/撤销和 connection管理的操作删掉，修改，添加
     */
    public static  void rollback() {

        Connection connection = threadLocalConn.get();
        if(connection != null) {//保证当前的连接是有效

            try {
                connection.rollback();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            } finally {
                try {
                    connection.close();
                } catch (SQLException throwables) {
                    throwables.printStackTrace();
                }
            }
        }

        threadLocalConn.remove();
    }



    //关闭连接, 老师再次强调： 在数据库连接池技术中，close 不是真的断掉连接
    //而是把使用的Connection对象放回连接池
    public static void close(ResultSet resultSet, Statement statement, Connection connection) {

        try {
            if (resultSet != null) {
                resultSet.close();
            }
            if (statement != null) {
                statement.close();
            }
            if (connection != null) {
                connection.close();
            }
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
    }
}

实现Member的功能查询等

一个规范接口

package com.yinhai.furns.dao;

import  com.yinhai.furns.javabean.Member;

/**
 * @author 银小海
 * @version 1.0
 * @email yinhai14@qq.com
 */
public interface MemberDAO {

    //小伙伴要自己分析，需要哪些方法
    //提供一个通过用户名返回对应的Member
    public Member queryMemberByUsername(String username);

    //提供一个保存Member对象到数据库/表member表
    public int saveMember(Member member);

    /**
     * 根据用户名和密码返回Member
     * @param username 用户名
     * @param password 密码
     * @return 返回的对象，如果不存在，返回null
     *
     */
    public Member queryMemberByUsernameAndPassword
    (String username, String password);
}

实现Member的功能查询添加等

package com.yinhai.furns.dao.impl;

import com.yinhai.furns.dao.BasicDAO;
import com.yinhai.furns.dao.MemberDAO;

import  com.yinhai.furns.javabean.Member;


/**
 * @author 银小海
 * @version 1.0
 * @email yinhai14@qq.com
 */
public class MemberDAOImpl extends BasicDAO<Member> implements MemberDAO {
    /**
     * 通过用户名返回对应的Member
     *
     * @param username 用户名
     * @return 对应的Member, 如果没有该Member, 返回 null
     */
    @Override
    public Member queryMemberByUsername(String username) {
        //老师提示，sql 先在sqlyog 测试，然后再拿到程序中
        //这里可以提高我们的开发效率，减少不必要的bug
        String sql = "SELECT `id`,`username`,`password`,`email` FROM `member`\n" +
                "WHERE `username` = ?";
        return querySingle(sql, Member.class, username);
    }

    /**
     * 保存一个会员
     *
     * @param member 传入Member对象
     * @return 返回-1 就是失败，返回其它的数字就是受影响的行数
     */
    @Override
    public int saveMember(Member member) {
        String sql = "INSERT INTO `member`(`username`,`password`,`email`) " +
                " VALUES(?,MD5(?), ?)";
        return update(sql, member.getUsername(),
                member.getPassword(), member.getEmail());
    }

    @Override
    public Member queryMemberByUsernameAndPassword(String username, String password) {

        String sql = "SELECT `id`,`username`,`password`,`email` FROM `member` " +
                " WHERE `username`=? and `password`=md5(?)";
        return querySingle(sql, Member.class, username, password);
    }


}

测试

package com.yinhai.furns.test;

import com.yinhai.furns.dao.MemberDAO;
import com.yinhai.furns.dao.impl.MemberDAOImpl;
import com.yinhai.furns.javabean.Member;

/**
 * @author 银小海
 * @version 1.0
 * @email yinhai14@qq.com
 */
public class MemberTest {
    public static void main(String[] args) {
        MemberDAO memberDAO = new MemberDAOImpl();
        if (memberDAO.queryMemberByUsername("admin") == null){
            System.out.println("null");
        }else {
            System.out.println("exist");
        }
        Member member = new Member(null,"jack","jack","135465@qq.com");
        if(memberDAO.saveMember(member) == 0){
            System.out.println("添加失败");
        }else{
            System.out.println("添加成功");
        }
    }
}

服务端提供注册

package com.yinhai.furns.test;

import com.yinhai.furns.javabean.Member;
import com.yinhai.furns.service.MemberService;
import com.yinhai.furns.service.impl.MemberServiceImpl;
import com.yinhai.furns.utils.JDBCUtilsByDruid;
import org.junit.jupiter.api.Test;

/**
 * @author 银小海
 * @version 1.0
 * @email yinhai14@qq.com
 */
public class MemberServiceTest {
    public static void main(String[] args) {
        MemberService memberService = new MemberServiceImpl();
        if (memberService.isExistsUsername("admin")){
            System.out.println("用户存在");
        }else{
            System.out.println("用户不存在");
        }
    }
    @Test
    public void test(){
        Member member = new Member(null, "tom", "tom", "643013242@qq.com");
        MemberService memberService = new MemberServiceImpl();
        boolean b = memberService.registerMember(member);
        if (b){
            System.out.println("注册成功");
        }else{
            System.out.println("注册失败");
        }
        JDBCUtilsByDruid.commit();
    }
}

一个Servlet提供前后端交流

注册成功请求转发到注册完成的页面

package com.yinhai.furns.web;

import com.yinhai.furns.javabean.Member;
import com.yinhai.furns.service.MemberService;
import com.yinhai.furns.service.impl.MemberServiceImpl;
import com.yinhai.furns.utils.JDBCUtilsByDruid;

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;

/**
 * @author 银小海
 * @version 1.0
 * @email yinhai14@qq.com
 */
@WebServlet(name = "RegisterServlet",urlPatterns = "/registerServlet")
public class RegisterServlet extends HttpServlet {
    private MemberService memberService = new MemberServiceImpl();
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String username = request.getParameter("user-name");
        String password = request.getParameter("user-password");
        String email = request.getParameter("user-email");
        if(!memberService.isExistsUsername(username)){
            System.out.println(username + "用户可用" + password + email);
            Member member = new Member(null,username,password,email);
            if (memberService.registerMember(member)) {
                request.getRequestDispatcher("/views/member/register_ok.jsp").forward(request,response);
                JDBCUtilsByDruid.commit();
            }else {
                request.getRequestDispatcher("/views/member/login_ok.jsp").forward(request,response);
            }
        }else{
            // System.out.println("用户不存在 返回注册页面");
            request.getRequestDispatcher("/views/member/register_fail.jsp").forward(request,response);
        }
    }

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

五、实现功能04-会员登录

1.输入用户名、密码后提交

2.判断会员是否存在

3.会员存在(数据库),显示登录成功页面

在DAO类编写对数据库操作也需要在父类以及接口内写该方法

public class MemberDAOImpl extends BasicDAO<Member> implements MemberDAO {
    @Override
    public Member queryMemberByUsernameAndPassword(String username, String password) {

        String sql = "SELECT `id`,`username`,`password`,`email` FROM `member` " +
                " WHERE `username`=? and `password`=md5(?)";
        return querySingle(sql, Member.class, username, password);
    }


}

在Service调用该方法

public class MemberServiceImpl implements MemberService {
    @Override
    public Member login(Member member) {
        //返回对象
        return memberDAO.queryMemberByUsernameAndPassword
                (member.getUsername(), member.getPassword());
    }
}

LoginServlet 用于验证前端

package com.yinhai.furns.web;

import com.sun.scenario.effect.impl.sw.sse.SSEBlend_SRC_OUTPeer;
import com.yinhai.furns.javabean.Member;
import com.yinhai.furns.service.MemberService;
import com.yinhai.furns.service.impl.MemberServiceImpl;

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;

/**
 * @author 银小海
 * @version 1.0
 * @email yinhai14@qq.com
 */
@WebServlet(name = "LoginServlet",urlPatterns = "/loginServlet")
public class LoginServlet extends HttpServlet {
    private MemberService memberService = new MemberServiceImpl();
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String username = request.getParameter("user-name");
        String password = request.getParameter("user-password");
        if (!memberService.isExistsUsername(username)){
            System.out.println("不存在 请重新登录");
            request.getRequestDispatcher("/views/member/login.html").forward(request,response);
            return;
        }
        if(memberService.login(new Member(null,username,password,null)) == null){
            System.out.println("密码错误 重新登录");
            request.getRequestDispatcher("/views/member/login.html").forward(request,response);
            return;
        }
        System.out.println("登录成功");
        request.getRequestDispatcher("/views/member/login_ok.jsp").forward(request,response);

    }

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

六、实现功能05 - 登录错误提示表单回显

在LoginServlet内添加回显以及消息提示

@WebServlet(name = "LoginServlet",urlPatterns = "/loginServlet")
public class LoginServlet extends HttpServlet {
    private MemberService memberService = new MemberServiceImpl();
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String username = request.getParameter("user-name");
        String password = request.getParameter("user-password");
        if (!memberService.isExistsUsername(username)){
            System.out.println("用户名或者密码错误");
            request.setAttribute("msg","用户名或者密码错误");
            request.setAttribute("user-name",username);
            request.getRequestDispatcher("/views/member/login.jsp").forward(request,response);
            return;
        }
        if(memberService.login(new Member(null,username,password,null)) == null){
            System.out.println("密码错误 重新登录");
            request.setAttribute("msg","密码错误 重新登录");
            request.setAttribute("user-name",username);
            request.getRequestDispatcher("/views/member/login.jsp").forward(request,response);
            return;
        }
        System.out.println("登录成功");
        request.getRequestDispatcher("/views/member/login_ok.jsp").forward(request,response);

    }

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

将前段页面改为jsp 并使用EL表达式

                        <div id="lg1" class="tab-pane active">
                            <div class="login-form-container">
                                <div class="login-register-form">
                                     <span style="float: right; font-weight: bold; font-size: 20pt; margin-left: 10px;">
                                         ${msg}
                                     </span>

添加动态显示用户名

在对应的地方使用el表达式即可

七、实现功能06 - 合并servlet

1.使用if else解决

使用switch - case进行判断

package com.yinhai.furns.web;

import com.yinhai.furns.javabean.Member;
import com.yinhai.furns.service.MemberService;
import com.yinhai.furns.service.impl.MemberServiceImpl;
import com.yinhai.furns.utils.JDBCUtilsByDruid;

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;

/**
 * @author 银小海
 * @version 1.0
 * @email yinhai14@qq.com
 */
@WebServlet(name = "MemberServlet", urlPatterns = "/memberServlet")
public class MemberServlet extends HttpServlet {
    private MemberService memberService = new MemberServiceImpl();

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String username = request.getParameter("user-name");
        String password = request.getParameter("user-password");
        String email = request.getParameter("user-email");
        String action = request.getParameter("action");
        System.out.println(action);
        switch (action) {
            case "login":
                if (!memberService.isExistsUsername(username)) {
                    System.out.println("用户不存在");
                    request.setAttribute("msg", "用户不存在");
                    request.getRequestDispatcher("/views/member/login.jsp").forward(request, response);
                    return;
                }
                if (memberService.login(new Member(null, username, password, null)) == null) {
                    System.out.println("密码错误 重新登录");
                    request.setAttribute("msg", "密码错误 重新登录");
                    request.setAttribute("username", username);
                    request.getRequestDispatcher("/views/member/login.jsp").forward(request, response);
                    return;
                }
                System.out.println("登录成功");
                request.getRequestDispatcher("/views/member/login_ok.jsp").forward(request, response);
                break;
            case "register":
                if (!memberService.isExistsUsername(username)) {
                    System.out.println(username + "用户可用" + password + email);
                    Member member = new Member(null, username, password, email);
                    if (memberService.registerMember(member)) {
                        request.getRequestDispatcher("/views/member/register_ok.jsp").forward(request, response);
                        JDBCUtilsByDruid.commit();
                    } else {
                        request.getRequestDispatcher("/views/member/register_fail.jsp").forward(request, response);
                    }
                } else {
                    System.out.println("用户存在 无法注册");
                    request.setAttribute("msg", "用户存在 无法注册");
                    request.getRequestDispatcher("/views/member/login.jsp").forward(request, response);
                }
                break;
        }


    }

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

2.反射 + 模版设计 + 动态绑定

package com.yinhai.furns.web;

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.Method;

/**
 * @author 银小海
 * @version 1.0
 * @email yinhai14@qq.com
 */
public abstract class BasicServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //解决接收到的数据中文乱码问题
        request.setCharacterEncoding("utf-8");

        //System.out.println("BasicServlet doPost()");
        //获取到action的值
        //老韩提示：如果我们使用了模板模式+反射+动态绑定，要满足action的value 和 方法名一致!!!
        String action = request.getParameter("action");
        //System.out.println("action=" + action);

        //使用反射,获取当前对象的方法
        //老韩解读
        //1.this 就是请求的Servlet
        //2.declaredMethod 方法对象就是当前请求的servlet对应的"action名字" 的方法, 该方法对象(declaredMethod)
        //  是变化的,根据用户请求
        //3.使用模板模式+反射+动态机制===> 简化多个 if--else if---..
        try {
            Method declaredMethod =
                    this.getClass().getDeclaredMethod(action, HttpServletRequest.class, HttpServletResponse.class);
            System.out.println("declaredMethod=" + declaredMethod);
            //使用方法对象，进行反射调用
            declaredMethod.invoke(this, request, response);

        } catch (Exception e) {
            //java基础->异常机制
            //将发生的异常,继续throw
            //老师心得体会: 异常机制是可以参与业务逻辑
            throw new RuntimeException(e);

        }

    }

}

然后子类servlet继承该Servlet 随后只写login以及register方法即可

package com.yinhai.furns.web;

import com.yinhai.furns.javabean.Member;
import com.yinhai.furns.service.MemberService;
import com.yinhai.furns.service.impl.MemberServiceImpl;
import com.yinhai.furns.utils.JDBCUtilsByDruid;

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;

/**
 * @author 银小海
 * @version 1.0
 * @email yinhai14@qq.com
 */
@WebServlet(name = "MemberServlet", urlPatterns = "/memberServlet")
public class MemberServlet extends BasicServlet {
    private MemberService memberService = new MemberServiceImpl();
    
    /**
     * 处理会员的注册
     *
     * @param request
     * @param response
     * @throws ServletException
     * @throws IOException
     */
    protected void register(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        System.out.println("======MemberServlet register()========");
        //接收用户注册信息-> 一定要去看前端页面字段..
        //用户名
        String username = request.getParameter("user-name");
        String password = request.getParameter("user-password");
        String email = request.getParameter("user-email");
        //获取用户提交验证码
        String code = request.getParameter("code");
        //从session中获取到验证码
        // String token = (String) request.getSession().getAttribute(KAPTCHA_SESSION_KEY);
        //立即删除session验证码->防止该验证码被重复使用
        // request.getSession().removeAttribute(KAPTCHA_SESSION_KEY);
        //如果token为空，并且和用户提交的验证码一致,就继续
        // if (token != null && token.equalsIgnoreCase(code)) {
            //判断这个用户名是不是可用
            if (!memberService.isExistsUsername(username)) {
                //注册
                //System.out.println("用户名 " + username + " 不存在, 可以注册");
                //构建一个Member对象
                Member member = new Member(null, username, password, email);
                if (memberService.registerMember(member)) {
                    //请求转发
                    request.getRequestDispatcher("/views/member/register_ok.jsp")
                            .forward(request, response);
                } else {
                    //请求转发
                    request.getRequestDispatcher("/views/member/register_fail.jsp")
                            .forward(request, response);
                }

            } else {
                //返回注册页面
                //后面可以加入提示信息...
                request.getRequestDispatcher("/views/member/login.jsp")
                        .forward(request, response);
            }
        // } else { //验证码不正确
        //     request.setAttribute("msg", "验证码不正确~");
        //     //如果前端需要回显某些数据
        //     request.setAttribute("username", username);
        //     request.setAttribute("email", email);
        //     //带回一个信息 要显示到注册选项页
        //     request.setAttribute("active", "register");
        //     request.getRequestDispatcher("/views/member/login.jsp").forward(request, response);
        // }

    }

    /**
     * 处理会员登录
     *
     * @param request
     * @param response
     * @throws ServletException
     * @throws IOException
     */
    protected void login(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        System.out.println("======MemberServlet login()========");
        //System.out.println("LoginServlet 被调用..");
        //老韩说明:如果在登录页面, 用户没有输入内容，就直接提交，后台接收到的是""
        String username = request.getParameter("user-name");
        String password = request.getParameter("user-password");
        Member member = memberService.login(new Member(null, username, password, null));
        if (member == null) { //用户没有在DB
            //System.out.println(member + " 登录失败...");
            //把登录错误信息,放入到request域 => 如果忘了，可以看servlet / jsp
            request.setAttribute("msg", "用户名或者密码错误");
            request.setAttribute("username", username);
            //页面转发
            request.getRequestDispatcher("/views/member/login.jsp")
                    .forward(request, response);
        } else { //用户在DB
            //System.out.println(member + " 登录成功~...");

            //将得到member对象放入到session
            request.getSession().setAttribute("member", member);
            //老师做了一个简单处理
            if ("admin".equals(member.getUsername())) {
                request.getRequestDispatcher("/views/manage/manage_menu.jsp")
                        .forward(request, response);
            } else {
                request.getRequestDispatcher("/views/member/login_ok.jsp")
                        .forward(request, response);
            }
        }

    }
}

八、功能07 - 后台管理家具

创建furn表

package com.yinhai.furns.web;

import com.yinhai.furns.dao.BasicDAO;
import com.yinhai.furns.javabean.Furn;
import com.yinhai.furns.service.FurnService;
import com.yinhai.furns.service.impl.FurnServiceImpl;

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.util.List;

/**
 * @author 银小海
 * @version 1.0
 * @email yinhai14@qq.com
 */
@WebServlet(name = "FurnServlet",urlPatterns = "/manager/furnServlet")
public class FurnServlet extends BasicServlet {
    private FurnService furnService = new FurnServiceImpl();
    /**
     * 这里我们使用前面的模板设计模式+反射+动态绑定来的调用到list方法
     *
     * @param req
     * @param resp
     * @throws ServletException
     * @throws IOException
     */
    protected void list(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("FurnServlet list方法被调...");
        List<Furn> furns = furnService.queryFurns();
        //把furns集合放入到request域
        req.setAttribute("furns", furns);
        for (Furn furn : furns) {
            System.out.println(furn);
        }
        //请求转发
        req.getRequestDispatcher("/views/manage/furn_manage.jsp")
                .forward(req, resp);
    }
}

通过jstl标签取出并输出

                            <c:forEach items="${requestScope.furns}" var="furn">
                                <tr>
                                    <td class="product-thumbnail">
                                        <a href="#"><img class="img-responsive ml-3" src="${furn.imgPath}"
                                                         alt=""/></a>
                                    </td>
                                    <td class="product-name"><a href="#">${furn.name}</a></td>
                                    <td class="product-name"><a href="#">${furn.maker}</a></td>
                                    <td class="product-price-cart"><span class="amount">${furn.price}</span></td>
                                    <td class="product-quantity">
                                            ${furn.sales}
                                    </td>
                                    <td class="product-quantity">
                                            ${furn.stock}
                                </tr>

编写admin的DAO

public class AdminDAOImpl extends BasicDAO implements AdminDAO {

    @Override
    public int saveAdmin(Admin admin) {
        String sql = "INSERT INTO `admin`(`username`,`password`) " +
                "VALUES(?,MD5(?))";
        return update(sql, admin.getUsername(),
                admin.getPassword());
    }

    @Override
    public Admin queryAdminByUsernameAndPassword(String username, String password) {
        String sql = "SELECT `id`,`username`,`password` FROM `admin` " +
                " WHERE `username`=? and `password`=md5(?)";
        return (Admin) querySingle(sql, Admin.class,username,password);
    }


}

编写对应的和前端交互的servlet

@WebServlet(name = "AdminServlet",urlPatterns = "/adminServlet")
public class AdminServlet extends BasicServlet {
    private AdminService adminService = new AdminServiceImpl();
    protected void login(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String username = request.getParameter("username");
        String password = request.getParameter("password");
        Admin admin = new Admin(null, username, password);

        if(adminService.login(admin) == null){
            System.out.println("管理员不存在");
            request.getRequestDispatcher("/views/manage/manage_login.jsp").forward(request,response);
            return;
        }
        request.getRequestDispatcher("/views/manage/manage_menu.jsp").forward(request,response);

    }
}

九、功能08 - 后台管理添加家具

@WebServlet(name = "FurnServlet",urlPatterns = "/manage/furnServlet")
public class FurnServlet extends BasicServlet {
    private FurnService furnService = new FurnServiceImpl();
    protected  void add(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
        //获取家居信息
        String uname = request.getParameter("name");
        String maker = request.getParameter("maker");
        String price = request.getParameter("price");
        String sales = request.getParameter("sales");
        String stock = request.getParameter("stock");
        String defaultPath = "assets/images/product-image/default.jpg";
        Furn furn = new Furn(null, uname, maker, new BigDecimal(price), new Integer(sales), new Integer(stock), defaultPath);
        System.out.println(furn);
        furnService.addFurn(furn);
        request.getRequestDispatcher("/manage/furnServlet?action=list")
               .forward(request, response);
    }

public class FurnServiceImpl implements FurnService {
    private FurnDAO furnDAO = new FurnDAOImpl();
    //定义属性FurnDAO对象
    /**
     * 返回家居信息
     * @return
     */
    @Override
    public List<Furn> queryFurns() {
        return furnDAO.queryFurns();
    }

    @Override
    public int addFurn(Furn furn) {
        return furnDAO.addFurn(furn);
    }
}

public class FurnDAOImpl extends BasicDAO implements FurnDAO {
    @Override
    public int addFurn(Furn furn) {
        String sql = "INSERT INTO furn(`id`,`name`,maker,price,sales,stock,img_path)\n" +
                "\tVALUES(NULL,?,?,?,?,?,?)";
        return update(sql,furn.getName(),
                furn.getMaker(),furn.getPrice(),furn.getSales(),furn.getStock(),furn.getImgPath());
    }
}

细节解决中文乱码问题在BasicDAO上设置request response的文本格式

细节解决表重复提交问题使用重定向即可

细节后端验证添加家具的合法性

 //我们可以对获取的到数据, 进行一个校验
        //1. 使用java的正则表达式来验证 sales是一个正整数
        //2. 如果没有通过校验，则直接返回furn_add.jsp -> request.setAttribute("mes","xx")
        //3. 这里可以直接进行转换
        //try {
        //    int i = Integer.parseInt(sales);
        //}catch (NumberFormatException e) {
        //    //System.out.println("转换异常...");
        //    req.setAttribute("mes", "销量数据格式不对...");
        //    //返回到furn_add.jsp
        //    req.getRequestDispatcher("/views/manage/furn_add.jsp")
        //            .forward(req, resp);
        //    return;
        //}

        //String stock = req.getParameter("stock");
        //图片的路径 imgPath 使用默认即可
        //Furn furn = null;
        //try {
        //    furn = new Furn(null, name, maker, new BigDecimal(price),
        //            new Integer(sales), new Integer(stock), "assets/images/product-image/default.jpg");
        //} catch (NumberFormatException e) {
        //    req.setAttribute("mes", "添加数据格式不对...");
        //    //返回到furn_add.jsp
        //    req.getRequestDispatcher("/views/manage/furn_add.jsp")
        //            .forward(req, resp);
        //    return;
        //}

        //后面我们会学习SpringMVC -> 专门的用于数据校验的规则/框架 JSR303... Hibernate Validator

细节使用工具类DataUtils 完成自动封装JavaBean

1. BeanUtils工具类，它可以一次性的把所有请求的参数注入到JavaBean中。

2. BeanUtils工具类，经常用于把Map中的值注入到JavaBean中，或者是对象属性值的拷贝操作

3. BeanUtils不是Jdk的类，需要导入需要的jar包: commons-beanutils-1.8.0.jar

commons-logging-1.1.1.jar

//使用BeanUtils完成javabean对象的自动封装.
        //
        // Furn furn = new Furn();
        // try {
        //    //讲 req.getParameterMap() 数据封装到furn 对象
        //    //使用反射将数据封装, 有一个前提就是表单提交的数据字段名
        //    //<input name="maker" style="width: 90%" type="text" value=""/>
        //    //需要和封装的Javabean的属性名一致
        //    BeanUtils.populate(furn, request.getParameterMap());
        // } catch (Exception e) {
        //    e.printStackTrace();
        // }
        // 自动将提交的数据，封装到Furn对象
        Furn furn =
                DataUtils.copyParamToBean(request.getParameterMap(), new Furn());
        System.out.println(furn);
        furnService.addFurn(furn);

public class DataUtils {
    //将方法，封装到静态方法，方便使用
    public static <T> T copyParamToBean(Map value, T bean) {
        try {
            BeanUtils.populate(bean, value);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return bean;
    }

}

在构造javabean的时候在Furn内赋予一个默认值给这个类自动装入

十、功能09 后台管理删除家具

前端对x图标进行绑定事件弹出是否删除该名字的家具

Servlet增加功能

@WebServlet(name = "FurnServlet",urlPatterns = "/manage/furnServlet")
public class FurnServlet extends BasicServlet {
protected void del(HttpServletRequest request,HttpServletResponse response){
        int id = DataUtils.parseInt(request.getParameter("id"), 0);
        System.out.println(furnService.deleteFurnById(id));
    }
}

Service增加功能

    public int deleteFurnById(int id) {
        return furnDAO.deleteFurnById(id);
    }

DAO类增加功能

public class FurnDAOImpl extends BasicDAO implements FurnDAO {
    public int deleteFurnById(int id) {
        String sql = "DELETE FROM furn WHERE id = ?";
        return update(sql,id);
    }
}

十一、功能实现 10 后台管理修改家具

查询对应的id的家具

protected void showFurn(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
        int id = DataUtils.parseInt(request.getParameter("id"),0);
        Furn furn = furnService.queryFurnById(id);
        System.out.println(furn);
        request.setAttribute("furn",furn);
        //请求转发
        request.getRequestDispatcher("/views/manage/furn_update.jsp").forward(request,response);
    }

以上完成回显操作下一步做修改的操作

  @Override
    public int updateFurn(Furn furn) {
        String sql = "UPDATE furn SET `name` = ? , `maker` = ? , `price` = ? , sales = ?" +
                " , stock = ? , `img_path` = ?" +
                " WHERE id = ?";
        return update(sql,furn.getName(),furn.getMaker(),
                furn.getPrice(),furn.getSales(),furn.getStock(),furn.getImgPath(),furn.getId());
    }

前端页面也调整使用jstl标签拿出

十二、功能实现11 分页显示

将分页作为一个Bean模型

package com.yinhai.furns.javabean;

import java.util.List;

/**
 * @author 银小海
 * @version 1.0
 * @email yinhai14@qq.com
 * 一个分页的数据模型 包含了分页的各种信息
 */
//用一个泛型 分页模型对应的数据类型是不确定的
public class Page<T> {
    //每页显示多少条记录可以在其他地方也用到 建议置为常量
    //ctrl + shift + u 切换大小写
    public static final Integer PAGE_SIZE = 3;

    //表示显示当前页
    private  Integer pageNo;

    //每页显示多少记录
    private  Integer pageSize = PAGE_SIZE;

    //表示共有多少页
    private Integer pageTotalCount;

    //表示的是共有多少条记录 通过totalRow和pageSize计算得到pageTotalCount
    private Integer totalRow;

    //表示当前页要显示的数据
    private List<T> items;

    //分页导航的字符串
    private String url;

    public Integer getPageNo() {
        return pageNo;
    }

    public void setPageNo(Integer pageNo) {
        this.pageNo = pageNo;
    }

    public Integer getPageSize() {
        return pageSize;
    }

    public void setPageSize(Integer pageSize) {
        this.pageSize = pageSize;
    }

    public Integer getPageTotalCount() {
        return pageTotalCount;
    }

    public void setPageTotalCount(Integer pageTotalCount) {
        this.pageTotalCount = pageTotalCount;
    }

    public Integer getTotalRow() {
        return totalRow;
    }

    public void setTotalRow(Integer totalRow) {
        this.totalRow = totalRow;
    }

    public List<T> getItems() {
        return items;
    }

    public void setItems(List<T> items) {
        this.items = items;
    }

    public String getUrl() {
        return url;
    }

    public void setUrl(String url) {
        this.url = url;
    }
}

分析 page的那些属性可以从数据库获取就把对应的属性交给DAO赋值

@Override
    public int getTotalRow() {
        String sql = "SELECT COUNT(*) FROM furn";
        // return (int) queryScalar(sql); => 会报转换异常
        return ((Number) queryScalar(sql)).intValue();
    }

    @Override
    public List<Furn> getPageItems(int begin, int pageSize) {
        String sql = "SELECT `id`,`name`,maker,price,sales,stock,img_path imgPath\n" +
                " FROM furn ";
        return null;
    }

其他的交给Service处理

public class FurnServiceImpl implements FurnService {
    @Override
    public Page<Furn> page(int pageNo, int pageSize) {
        Page<Furn> page = new Page<>();
        page.setPageNo(pageNo);
        page.setPageSize(pageSize);
        int totalRow = furnDAO.getTotalRow();
        page.setTotalRow(totalRow);
        //pageTotalCount最大页数 需要通过算法计算得到
        int pageTotalCount = totalRow / pageSize;
        if(totalRow % pageSize > 0){
            pageTotalCount += 1;
        }
        page.setPageTotalCount(pageTotalCount);
        //private List<T> items
        //计算begin
        //private List<T> items
        //老师开始计算begin-> 小小算法
        //验证: pageNo = 1 pageSize = 3 => begin =0
        //验证: pageNo = 3 pageSize = 2 => begin =4
        //OK => 但是注意这里隐藏一个坑, 现在你看不到, 后面会暴露
        int begin = (pageNo - 1) * pageSize;
        List<Furn> pageItems = furnDAO.getPageItems(begin, pageSize);
        page.setItems(pageItems);
        //还差一个url => 分页导航，先放一放
        return page;
    }
}

Servlet调用

protected void page(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        int pageNo = DataUtils.parseInt(req.getParameter("pageNo"), 1);
        int pageSize = DataUtils.parseInt(req.getParameter("pageSize"), Page.PAGE_SIZE);

        //调用service方法, 获取Page对象
        Page<Furn> page = furnService.page(pageNo, pageSize);
        //将page放入到request域
        req.setAttribute("page", page);
        //请求转发到furn_manage.jsp
        req.getRequestDispatcher("/views/manage/furn_manage.jsp")
                .forward(req, resp);
    }

十三、功能实现 12 - 分页导航

<!--  Pagination Area Start 分页导航条 -->
        <div class="pro-pagination-style text-center mb-md-30px mb-lm-30px mt-6" data-aos="fade-up">
            <ul>
                <%--如果当前页 > 1 , 就显示上一页--%>
                <c:if test="${requestScope.page.pageNo > 1}">
                    <li><a href="manage/furnServlet?action=page&pageNo=${requestScope.page.pageNo - 1}">上一页</a></li>
                </c:if>
                <%--<li><a class="active" href="#">3</a></li>--%>
                <%--<li><a href="#">4</a></li>--%>
                <%--<li><a href="#">5</a></li>--%>
                <%--    显示所有的分页数， 先容易，再困难
                    老师思路: 先确定开始页数 begin 第1页
                            再确定结束页数 end 第pageTotalCount页
                    学生困惑：如果页数很多，怎么办? => 算法最多显示5页[这个规则可以由程序员决定.]
                            希望，小伙伴自己先想一想...=> 后面

                    老师分析
                    1. 如果总页数<=5, 就全部显示
                    2. 如果总页数>5, 按照如下规则显示(这个规则是程序员/业务来确定):
                    2.1 如果当前页是前3页, 就显示1-5
                    2.2 如果当前页是后3页, 就显示最后5页
                    2.3 如果当前页是中间页, 就显示 当前页前2页, 当前页 , 当前页后两页

                    这里的关键就是要根据不同的情况来初始化begin, end
                --%>
                <c:choose>
                    <%--如果总页数<=5, 就全部显示--%>
                    <c:when test="${requestScope.page.pageTotalCount <=5 }">
                        <c:set var="begin" value="1"/>
                        <c:set var="end" value="${requestScope.page.pageTotalCount}"/>
                    </c:when>
                    <%--如果总页数>5--%>
                    <c:when test="${requestScope.page.pageTotalCount > 5}">
                        <c:choose>
                            <%--如果当前页是前3页, 就显示1-5--%>
                            <c:when test="${requestScope.page.pageNo <= 3}">
                                <c:set var="begin" value="1"/>
                                <c:set var="end" value="5"/>
                            </c:when>
                            <%--如果当前页是后3页, 就显示最后5页--%>
                            <c:when test="${requestScope.page.pageNo > requestScope.page.pageTotalCount - 3}">
                                <c:set var="begin" value="${requestScope.page.pageTotalCount - 4}"/>
                                <c:set var="end" value="${requestScope.page.pageTotalCount}"/>
                            </c:when>
                            <%--如果当前页是中间页, 就显示 当前页前2页, 当前页 , 当前页后两页--%>
                            <c:otherwise>
                                <c:set var="begin" value="${requestScope.page.pageNo - 2}"/>
                                <c:set var="end" value="${requestScope.page.pageNo + 2}"/>
                            </c:otherwise>
                        </c:choose>
                    </c:when>
                </c:choose>

                <c:forEach begin="${begin}" end="${end}" var="i">
                    <%--如果i是当前页, 就使用class="active" 修饰--%>
                    <c:if test="${i == requestScope.page.pageNo}">
                        <li><a class="active" href="manage/furnServlet?action=page&pageNo=${i}">${i}</a></li>
                    </c:if>
                    <c:if test="${i != requestScope.page.pageNo}">
                        <li><a href="manage/furnServlet?action=page&pageNo=${i}">${i}</a></li>
                    </c:if>
                </c:forEach>

                <%--如果当前页 < 总页数 , 就显示下一页--%>
                <c:if test="${requestScope.page.pageNo < requestScope.page.pageTotalCount}">
                    <li><a href="manage/furnServlet?action=page&pageNo=${requestScope.page.pageNo + 1}">下一页</a></li>
                </c:if>
                <li><a href="#">共 ${requestScope.page.pageTotalCount} 页</a></li>
            </ul>
        </div>
        <!--  Pagination Area End -->

进行修改删除添加家具之后能够回显到原来操作所在的页面

修改一步步转发到最后重定向到page页面

这几个都这么做都在修改请求转发地址上完成

@WebServlet(name = "FurnServlet", urlPatterns = "/manage/furnServlet")
public class FurnServlet extends BasicServlet {
    protected void add(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //获取家居信息
        // String uname = request.getParameter("name");
        // String maker = request.getParameter("maker");
        // String price = request.getParameter("price");
        // String sales = request.getParameter("sales");
        //
        //
        // String stock = request.getParameter("stock");
        // String defaultPath = "assets/images/product-image/default.jpg";
        // Furn furn = new Furn(null, uname, maker, new BigDecimal(price), new Integer(sales), new Integer(stock), defaultPath);
        //我们可以对获取的到数据, 进行一个校验
        //1. 使用java的正则表达式来验证 sales是一个正整数
        //2. 如果没有通过校验，则直接返回furn_add.jsp -> request.setAttribute("mes","xx")
        //3. 这里可以直接进行转换
        //try {
        //    int i = Integer.parseInt(sales);
        //}catch (NumberFormatException e) {
        //    //System.out.println("转换异常...");
        //    req.setAttribute("mes", "销量数据格式不对...");
        //    //返回到furn_add.jsp
        //    req.getRequestDispatcher("/views/manage/furn_add.jsp")
        //            .forward(req, resp);
        //    return;
        //}

        //String stock = req.getParameter("stock");
        //图片的路径 imgPath 使用默认即可
        //Furn furn = null;
        //try {
        //    furn = new Furn(null, name, maker, new BigDecimal(price),
        //            new Integer(sales), new Integer(stock), "assets/images/product-image/default.jpg");
        //} catch (NumberFormatException e) {
        //    req.setAttribute("mes", "添加数据格式不对...");
        //    //返回到furn_add.jsp
        //    req.getRequestDispatcher("/views/manage/furn_add.jsp")
        //            .forward(req, resp);
        //    return;
        //}

        //后面我们会学习SpringMVC -> 专门的用于数据校验的规则/框架 JSR303... Hibernate Validator
        //这里我们使用第二种方式, 完成将前端提交的数据， 封装成Furn的Javabean对象
        //使用BeanUtils完成javabean对象的自动封装.
        //
        // Furn furn = new Furn();
        // try {
        //    //讲 req.getParameterMap() 数据封装到furn 对象
        //    //使用反射将数据封装, 有一个前提就是表单提交的数据字段名
        //    //<input name="maker" style="width: 90%" type="text" value=""/>
        //    //需要和封装的Javabean的属性名一致
        //    BeanUtils.populate(furn, request.getParameterMap());
        // } catch (Exception e) {
        //    e.printStackTrace();
        // }
        // 自动将提交的数据，封装到Furn对象
        Furn furn =
                DataUtils.copyParamToBean(request.getParameterMap(), new Furn());
        System.out.println(furn);
        furnService.addFurn(furn);

        //老师说明: 因为这里使用请求转发, 当用户刷新页面时, 会重新发出一次添加请求
        // request.getRequestDispatcher("/manage/furnServlet?action=list")
        //        .forward(request, response);
        //就会造成数据重复提交： 解决方案使用 重定向即可.
        //因为重定向实际是让浏览器重新发请求, 所以我们回送的url , 是一个完整url
        // response.sendRedirect(request.getContextPath() + "/manage/furnServlet?action=list");
        //以分页的方式显示
        response.sendRedirect(request.getContextPath()
                + "/manage/furnServlet?action=page&pageNo=" + request.getParameter("pageNo"));
    }

    protected void del(HttpServletRequest request, HttpServletResponse response) throws IOException {
        int id = DataUtils.parseInt(request.getParameter("id"), 0);
        System.out.println(furnService.deleteFurnById(id));

        response.sendRedirect(request.getContextPath()
                + "/manage/furnServlet?action=page&pageNo=" + request.getParameter("pageNo"));
    }

    protected void showFurn(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        int id = DataUtils.parseInt(request.getParameter("id"), 0);
        Furn furn = furnService.queryFurnById(id);
        System.out.println(furn);
        request.setAttribute("furn", furn);
        //再把获取到的showPage再传回去
        // request.setAttribute("pageNo",request.getParameter("pageNo"));
        // 如果是在同一个作用域request内的请求是不需要再转发的 在下个页面可以用param.pageNo获取
        //请求转发
        request.getRequestDispatcher("/views/manage/furn_update.jsp").forward(request, response);
    }

    protected void update(HttpServletRequest request, HttpServletResponse response) throws IOException {
        Furn furn = DataUtils.copyParamToBean(request.getParameterMap(), new Furn());
        System.out.println("update" + furn);
        System.out.println(furnService.updateFurn(furn));
        //请求重定向
        // response.sendRedirect(request.getContextPath() + "/manage/furnServlet?action=list");
        //这里考虑分页转发
        System.out.println(request.getContextPath()
                + "/manage/furnServlet?action=page&pageNo=" + request.getParameter("pageNo"));
        response.sendRedirect(request.getContextPath()
                + "/manage/furnServlet?action=page&pageNo=" + request.getParameter("pageNo"));
    }
    protected void page(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        int pageNo = DataUtils.parseInt(req.getParameter("pageNo"), 1);
        int pageSize = DataUtils.parseInt(req.getParameter("pageSize"), Page.PAGE_SIZE);

        //调用service方法, 获取Page对象
        Page<Furn> page = furnService.page(pageNo, pageSize);
        if(page.getItems().size() == 0){
            page = furnService.page(page.getPageTotalCount(), pageSize);
        }
        //将page放入到request域
        req.setAttribute("page", page);
        //请求转发到furn_manage.jsp
        req.getRequestDispatcher("/views/manage/furn_manage.jsp")
                .forward(req, resp);
    }


}