Javaweb学习笔记day10、11---项目四阶段_黑马javaweb 2023学习笔记day10-优快云博客

本文链接：https://blog.youkuaiyun.com/Wynb1020/article/details/121864685

本文详细介绍了JavaWeb项目中购物车功能的实现，包括保持登录状态、注销登录、Kaptcha验证码的配置与刷新、购物车模型如CartItem和Cart的设计以及相关操作。同时讲解了从注册到购物车管理的全过程，如添加商品、显示购物车列表、清空购物车、修改购物车项数量等操作，并涉及到BigDecimal的精度调整问题。

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项目四阶段搭建

项目搭建
- v3 -> v4

保持登录状态

需求
- 登录成功之后，在login_success.html、index.html页面，显示用户信息。
分析
- ServeltRequest：登录成功之后，使用的是重定向，而重定向是新的请求
- ServletContext : 登录成功之后，所有人都可以拿到你的个人的用户信息
- Cookie：登录成功之后，将个人信息存储到浏览器的缓存文件，存在一定的安全问题
- Session：登录成功之后，将个人信息存储到服务器
代码实现

public void login(HttpServletRequest request, HttpServletResponse response) {
    //处理请求
    String username = request.getParameter("username");
    String password = request.getParameter("password");
    UserService userService = new UserServiceImpl();
    try {
        User user = userService.login(username, password);
        //调度页面
        if (null != user) {
            //登录成功 ,将用户信息存储到session, 跳转到login_success.html (重定向)
            request.getSession().setAttribute("existUser", user);
            response.sendRedirect(request.getContextPath() + "/user?method=toLoginSuccessPage");
        } else {
            //登录失败 , 跳转回login.html (请求转发)
            String errorMsg = "账户或密码错误!";
            request.setAttribute("errorMsg", errorMsg);
            toLoginPage(request, response);
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
}

//index.html

<!--          登录前风格-->
<div class="topbar-right" th:if="${null == session.existUser}">
    <a th:href="@{/user(method=toLoginPage)}" class="login">登录</a>

    <a th:href="@{/user(method=toRegistPage)}" class="register">注册</a>
    <a
            href="pages/cart/cart.html"
            class="cart iconfont icon-gouwuche">
        购物车
        <div class="cart-num">3</div>
    </a>
    <a th:href="@{/manager.html}" class="admin">后台管理</a>
</div>
<!--          登录后风格-->
<div class="topbar-right" th:if="${null != session.existUser}">
    <span>欢迎你<b th:text="${session.existUser.userName}">张总</b></span>
    <a href="#" class="register">注销</a>
    <a
            href="pages/cart/cart.jsp"
            class="cart iconfont icon-gouwuche
         ">
        购物车
        <div class="cart-num">3</div>
    </a>
    <a href="pages/manager/book_manager.html" class="admin">后台管理</a>
</div>

注销登录功能

需求
- 在index.html、login_success.html页面，点击注销按钮，完成注销功能，回到index.html
代码实现

/**
 * 注销登录功能
 * @param request
 * @param response
 */
public void logout(HttpServletRequest request,HttpServletResponse response){
    //将保存在session的用户信息移除
    request.getSession().removeAttribute(BookstoreConstant.SESSION_KEY_USER);
    //移除成功之后
    try {
        response.sendRedirect(request.getContextPath() + "/index.html");
    } catch (IOException e) {
        e.printStackTrace();
    }
}

<a th:href="@{/user(method=logout)}">注销</a>&nbsp;&nbsp;

图片验证码Kaptcha

概述
- 通过让用户填写验证码并在服务器端检查，防止浏览器端使用程序恶意访问。
开发步骤
- ①引入Kaptcha的相关jar包
- ②配置一个KaptchaServlet
  - 用于生成一个图片验证码 , 该图片验证码的内容存储到了Session中(KAPTCHA_SESSION_KEY)
- ③测试匹配图片验证码
①引入Kaptcha的相关jar包
②配置一个KaptchaServlet

<!--图片验证码-->
<servlet>
    <servlet-name>KaptchaServlet</servlet-name>
    <servlet-class>com.google.code.kaptcha.servlet.KaptchaServlet</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>KaptchaServlet</servlet-name>
    <url-pattern>/kaptcha</url-pattern>
</servlet-mapping>

③测试匹配图片验证码

@WebServlet("/demo01")
public class Demo01Servlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //获取用户输入的验证码
        String inputCode = req.getParameter("code");
        //获取图片验证码的内容
        Object existCode = req.getSession().getAttribute("KAPTCHA_SESSION_KEY");
        //两个验证码匹配
        System.out.println(inputCode.equals(existCode) ? "验证码正确!" :"验证码错误!");
    }

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

Kaptcha相关配置

代码实现

<!--图片验证码-->
<servlet>
    <servlet-name>KaptchaServlet</servlet-name>
    <servlet-class>com.google.code.kaptcha.servlet.KaptchaServlet</servlet-class>

    <!--设置边框-->
    <init-param>
        <param-name>kaptcha.border</param-name>
        <param-value>yes</param-value>
    </init-param>
    <!--设置边框颜色-->
    <init-param>
        <param-name>kaptcha.border.color</param-name>
        <param-value>red</param-value>
    </init-param>
    <!--设置边框粗细-->
    <init-param>
        <param-name>kaptcha.border.thickness</param-name>
        <param-value>10</param-value>
    </init-param>

    <!--设置内容-->
    <init-param>
        <param-name>kaptcha.textproducer.char.string</param-name>
        <param-value>0123456789</param-value>
    </init-param>

    <!--设置验证码长度-->
    <init-param>
        <param-name>kaptcha.textproducer.char.length</param-name>
        <param-value>4</param-value>
    </init-param>

    <!--设置字体样式-->
    <init-param>
        <param-name>kaptcha.textproducer.font.names</param-name>
        <param-value>楷体</param-value>
    </init-param>
    <!--设置字体大小-->
    <init-param>
        <param-name>kaptcha.textproducer.font.size</param-name>
        <param-value>45</param-value>
    </init-param>

    <!--设置字体颜色-->
    <init-param>
        <param-name>kaptcha.textproducer.font.color</param-name>
        <param-value>green</param-value>
    </init-param>
    <!--设置字符间距-->
    <init-param>
        <param-name>kaptcha.textproducer.char.space</param-name>
        <param-value>5</param-value>
    </init-param>
    <!--设置干扰线-->
    <init-param>
        <param-name>kaptcha.noise.impl</param-name>
        <param-value>com.google.code.kaptcha.impl.DefaultNoise</param-value>
    </init-param>

    <!--设置干扰线颜色-->
    <init-param>
        <param-name>kaptcha.noise.color</param-name>
        <param-value>red</param-value>
    </init-param>
    <!--设置背景起始颜色-->
    <init-param>
        <param-name>kaptcha.background.clear.from</param-name>
        <param-value>pink</param-value>
    </init-param>
    <!--设置背景结束颜色-->
    <init-param>
        <param-name>kaptcha.background.clear.to</param-name>
        <param-value>red</param-value>
    </init-param>

</servlet>

注册功能引入kaptcha

需求
- 在regist.html页面，引入kaptcha图片验证码
代码实现

//regist.html

<div class="form-item">
    <div>
        <label>验证码:</label>
        <div class="verify">
            <input type="text" placeholder="请输入验证码" @change="checkCode()" v-model="code" name="code"/>
            <!--访问KaptchaServlet-->
            <img th:src="@{/kaptcha}" alt="无法获取验证码!" style="margin-left: 10px;width: 150px;height: 50px"/>
        </div>
    </div>
    <span class="errMess" v-text="codeErrorMsg">请输入正确的验证码</span>
</div>

public void regist(HttpServletRequest req, HttpServletResponse resp) {
    //使用BeanUtils自动封装
    User inputUser = new User();
    try {
        //校验图片验证码
        //获取用户输入的图片验证码
        String inputCode = req.getParameter("code");
        //获取图片验证码的内容
        Object existCode = req.getSession().getAttribute("KAPTCHA_SESSION_KEY");
        if (!inputCode.equals(existCode)) {
            //图片验证码校验失败
            String codeErrorMsg = "验证码错误!";
            req.setAttribute("codeErrorMsg", codeErrorMsg);
            toRegistPage(req, resp);
            return;
        }

        BeanUtils.populate(inputUser, req.getParameterMap());
        System.out.println("inputUser = " + inputUser);
        UserService userService = new UserServiceImpl();
        //校验用户名是否存在
        User dbUser = userService.selectUserByUsername(inputUser.getUserName());
        if (null != dbUser) {
            //注册失败，用户名已经存在 , 跳转回regist.html (转发)
            resp.setContentType("text/html;charset=utf-8");
            String errorMsg = "用户名已经存在!";
            req.setAttribute("errorMsg", errorMsg);
            toRegistPage(req, resp);
            return;
        }

        int addUser = userService.addUser(inputUser);
        if (addUser > 0) {
            //添加成功 , 跳转到regist_success.html (重定向)
            resp.sendRedirect(req.getContextPath() + "/user?method=toRegistSuccessPage");
        } else {
            //添加失败 , 跳转回regist.html (转发)
            toLoginPage(req, resp);
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
}

刷新图片验证码(掌握)

需求
- 点击图片验证码并刷新
代码实现

<img id="codeImg" @click="refreshImg()" th:src="@{/kaptcha}" alt="无法获取验证码!" style="margin-left: 10px;width: 150px;height: 50px"/>

<script>
    /**
    * 刷新图片验证码
    */
    refreshImg(){
        var imgEle = document.getElementById("codeImg");
        imgEle.setAttribute("src","kaptcha");
    }
</script>

跳转到购物车

需求
- 在index.html页面，点击购物车按钮，跳转到cart.html页面。
代码实现

@WebServlet("/protected/cart")
public class ProtectedCartServlet extends ModelBaseServlet {

    /**
     * 转发到cart.html
     *
     * @param request
     * @param response
     */
    public void toCartPage(HttpServletRequest request, HttpServletResponse response) {
        try {
            processTemplate("pages/cart/cart", request, response);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }


}

//index.html

<!--          登录前风格-->
<div class="topbar-right" th:if="${null == session.existUser}">
    <a th:href="@{/user(method=toLoginPage)}" class="login">登录</a>

    <a th:href="@{/user(method=toRegistPage)}" class="register">注册</a>
    <a
            th:href="@{/protected/cart(method=toCartPage)}"
            class="cart iconfont icon-gouwuche">
        购物车
        <div class="cart-num">3</div>
    </a>
    <a th:href="@{/manager.html}" class="admin">后台管理</a>
</div>
<!--          登录后风格-->
<div class="topbar-right" th:if="${null != session.existUser}">
    <span>欢迎你<b th:text="${session.existUser.userName}">张总</b></span>
    <a th:href="@{/user(method=logout)}" class="register">注销</a>
    <a
            th:href="@{/protected/cart(method=toCartPage)}"
            class="cart iconfont icon-gouwuche">
        购物车
        <div class="cart-num">3</div>
    </a>
    <a href="pages/manager/book_manager.html" class="admin">后台管理</a>
</div>

购物车模型之CartItem

成员变量
- bookId : 图书编号
- imgPath ：图书图片
- bookName : 图书名称
- count : 图书数量
- price : 图书价格
- amount : 小计
  - amount = count * price
成员方法
- countIncrease() : 购物车项数量加一
- countDecrease() : 购物车项数量减一
代码实现

/**
 * 购物车模型之购物车项
 */
public class CartItem {

    private Integer bookId;//图书编号
    private String imgPath;//图书图片
    private String bookName;//图书名称
    private Integer count;//图书数量
    private Double price;//图书价格
    private Double amount;//小计

    public CartItem() {
    }

    public CartItem(Integer bookId, String imgPath, String bookName, Integer count, Double price, Double amount) {
        this.bookId = bookId;
        this.imgPath = imgPath;
        this.bookName = bookName;
        this.count = count;
        this.price = price;
        this.amount = amount;
    }


    public Integer getBookId() {
        return bookId;
    }

    public void setBookId(Integer bookId) {
        this.bookId = bookId;
    }

    public String getImgPath() {
        return imgPath;
    }

    public void setImgPath(String imgPath) {
        this.imgPath = imgPath;
    }

    public String getBookName() {
        return bookName;
    }

    public void setBookName(String bookName) {
        this.bookName = bookName;
    }

    public Integer getCount() {
        return count;
    }

    public void setCount(Integer count) {
        this.count = count;
    }

    public Double getPrice() {
        return price;
    }

    public void setPrice(Double price) {
        this.price = price;
    }

    public Double getAmount() {
        return this.count * this.price;
    }

    public void setAmount(Double amount) {
        this.amount = amount;
    }

    public void countIncrease(){
        this.count++;
    }

    public void countDecrease() {
        this.count--;
    }

    @Override
    public String toString() {
        return "CartItem{" +
                "bookId=" + bookId +
                ", imgPath='" + imgPath + '\'' +
                ", bookName='" + bookName + '\'' +
                ", count=" + count +
                ", price=" + price +
                ", amount=" + amount +
                '}';
    }
}

购物车模型之Cart

成员变量
- 商品总数量
- 商品总金额
- 购物车项列表
成员方法
- 获取商品总数量
- 获取商品总金额
- 获取购物车项列表
- 指定购物车项数量减一
- 指定购物车项数量加一
- 修改指定购物车项数量
- 删除指定购物车项
- 将图书添加到购物车
代码实现

/**
 * 购物车模型之Cart
 */
public class Cart {

    private Integer totalCount;//商品总数量

    private Double totalAmount;//商品总金额(总计)

    private Map<Integer,CartItem> cartItemMap = new HashMap<>();  //购物车项列表


    /**
     * 获取商品总数量 = 购物车项数量相加
     * @return
     */
    public Integer getTotalCount() {
        Collection<CartItem> cartItems = cartItemMap.values();
        Integer totalCount = 0 ;
        for (CartItem cartItem : cartItems) {
            totalCount = totalCount +  cartItem.getCount();
        }
        this.totalCount = totalCount;
        return this.totalCount;
    }


    /**
     * 获取商品总金额 = 购物车项小计相加
     * @return
     */
    public Double getTotalAmount() {
        Collection<CartItem> cartItems = cartItemMap.values();
        Double totalAmount = 0.0;
        for (CartItem cartItem : cartItems) {
            Double amount = cartItem.getAmount();
            totalAmount = totalAmount + amount;
        }
        this.totalAmount = totalAmount;
        return this.totalAmount;
    }


    /**
     * 获取购物车项列表
     * @return
     */
    public Map<Integer, CartItem> getCartItemMap() {
        return cartItemMap;
    }


    /**
     * 指定购物车项数量减一
     * @param bookId
     */
    public void cartItemCountDecrease(Integer bookId){
        CartItem cartItem = cartItemMap.get(bookId);
        cartItem.countDecrease();
    }

    /**
     * 指定购物车项数量加一
     * @param bookId
     */
    public void cartItemCountIncrease(Integer bookId){
        CartItem cartItem = cartItemMap.get(bookId);
        cartItem.countIncrease();
    }

    /**
     * 修改指定购物车项的数量
     * @param bookId
     * @param newCount ： 新数量
     */
    public void updateCartItemCount(Integer bookId , Integer newCount){
        CartItem cartItem = cartItemMap.get(bookId);
        cartItem.setCount(newCount);
    }

    /**
     * 删除指定购物车项
     * @param bookId
     */
    public void removeCartItem(Integer bookId){
        cartItemMap.remove(bookId);
    }

    /**
     * 将图书添加到购物车
     * @param book
     */
    public void addBook2Cart(Book book){
        //判断购物车是否包含该图书
        Integer bookId = book.getBookId();
        if (cartItemMap.containsKey(bookId)) {
            //包含该图书,在原来的购物车项数量加一
            cartItemCountIncrease(bookId);

        } else {
            //不包含该图书,创建新的购物车项
            CartItem cartItem = new CartItem(
                    bookId,
                    book.getImgPath(),
                    book.getBookName(),
                    1,
                    book.getPrice(),
                    1 * book.getPrice()
            );
            cartItemMap.put(bookId,cartItem);

        }
    }


}

public class Demo01 {

    public static void main(String[] args) {
        Book book1 = new Book(
                1,
                "java",
                "oldqiu",
                100.0,
                1000,
                10000,
                "girl.jpg"
        );

        Book book2 = new Book(
                2,
                "javase",
                "搞死你",
                100.0,
                10000,
                100000,
                "girl2.jpg"
        );

        Book book3 = new Book(
                3,
                "linux",
                "linux",
                100.0,
                20000,
                200000,
                "girl3.jpg"
        );

        Cart cart = new Cart();
        cart.addBook2Cart(book1);
        cart.addBook2Cart(book1);
        cart.addBook2Cart(book1);
        cart.addBook2Cart(book1);
        cart.addBook2Cart(book2);
        cart.addBook2Cart(book3);

        System.out.println("总数量 : " + cart.getTotalCount());
        System.out.println("总金额 : " + cart.getTotalAmount());
        System.out.println("购物车项列表 : " + cart.getCartItemMap());

    }

}

添加商品进购物车

需求
- 在index.html，点击加入购物车按钮，加入购物车成功后，跳转到index.html，显示商品总数量
代码实现

//index.html

<a th:href="@{/protected/cart(method=addBook2Cart,bookId=${book.bookId})}">
    加入购物车
</a>

@WebServlet("/protected/cart")
public class ProtectedCartServlet extends ModelBaseServlet {



    /**
     * 将图书添加到购物车
     *
     * @param request
     * @param response
     */
    public void addBook2Cart(HttpServletRequest request, HttpServletResponse response) {
        try {
            Integer bookId = Integer.parseInt(request.getParameter("bookId"));
            System.out.println("bookId = " + bookId);
            BookService bookService = new BookServiceImpl();
            Book book = bookService.selectBookById(bookId);
            //判断之前有没有购物车
            Cart cart = (Cart) request.getSession().getAttribute(BookstoreConstant.SESSION_KEY_CART);
            if (null == cart) {
                //之前没有购物车
                cart = new Cart();
            } else {
                //之前有购物车
            }
            cart.addBook2Cart(book);
            request.getSession().setAttribute(BookstoreConstant.SESSION_KEY_CART, cart);

            //购物车添加完成 , 跳转到index.html (重定向)
            response.sendRedirect(request.getContextPath() + "/index.html");

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


}

//index.html

<!--          登录前风格-->
<div class="topbar-right" th:if="${null == session.existUser}">
    <a th:href="@{/user(method=toLoginPage)}" class="login">登录</a>

    <a th:href="@{/user(method=toRegistPage)}" class="register">注册</a>
    <a
            th:href="@{/protected/cart(method=toCartPage)}"
            class="cart iconfont icon-gouwuche">
        购物车
        <div class="cart-num"
             th:if="${session.existCart==null||session.existCart.totalCount==0}">
            0
        </div>
        <div class="cart-num"
             th:unless="${session.existCart==null||session.existCart.totalCount==0}"
             th:text="${session.existCart.totalCount}">
            0
        </div>
    </a>
    <a th:href="@{/manager.html}" class="admin">后台管理</a>
</div>
<!--          登录后风格-->
<div class="topbar-right" th:if="${null != session.existUser}">
    <span>欢迎你<b th:text="${session.existUser.userName}">张总</b></span>
    <a th:href="@{/user(method=logout)}" class="register">注销</a>
    <a
            th:href="@{/protected/cart(method=toCartPage)}"
            class="cart iconfont icon-gouwuche">
        购物车
        <div class="cart-num"
             th:if="${session.existCart==null||session.existCart.totalCount==0}">
            0
        </div>
        <div class="cart-num"
             th:unless="${session.existCart==null||session.existCart.totalCount==0}"
             th:text="${session.existCart.totalCount}">
            0
        </div>
    </a>
    <a href="pages/manager/book_manager.html" class="admin">后台管理</a>
</div>

显示购物车列表

需求
- 在index.html，点击购物车按钮，跳转到cart.html，并展示购物车列表。
代码实现

@WebServlet("/protected/cart")
public class ProtectedCartServlet extends ModelBaseServlet {

    /**
     * 转发到cart.html
     *
     * @param request
     * @param response
     */
    public void toCartPage(HttpServletRequest request, HttpServletResponse response) {
        try {
            //获取购物车信息
            //Object existCart = request.getSession().getAttribute(BookstoreConstant.SESSION_KEY_CART);

            processTemplate("pages/cart/cart", request, response);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

//cart.html

<div class="w">

    <!--购物车项列表-->
    <table>
        <thead>
        <tr>
            <th>图片</th>
            <th>商品名称</th>

            <th>数量</th>
            <th>单价</th>
            <th>金额</th>
            <th>操作</th>
        </tr>
        </thead>
        <!-- 购物车为空时 -->
        <tbody th:if="${session.existCart==null||session.existCart.totalCount==0}">
        <tr>
            <td colspan="6">
                <a href="index.html">购物车空空如也，请抓紧购物吧!!!!</a>
            </td>
        </tr>
        </tbody>
        <!-- 购物车不为空时 -->
        <tbody th:unless="${session.existCart==null||session.existCart.totalCount==0}">
        <!--cartItemEntry : 键值对对象(键:bookId, 值:CartItem对象)-->
        <tr th:each="cartItemEntry : ${session.existCart.cartItemMap}">
            <td>
                <img th:src="${cartItemEntry.value.imgPath}" alt=""/>
            </td>
            <td th:text="${cartItemEntry.value.bookName}">活着</td>
            <td>
                <span class="count">-</span>
                <input class="count-num" type="text" th:value="${cartItemEntry.value.count}"/>
                <span class="count">+</span>
            </td>
            <td th:text="${cartItemEntry.value.price}">36.8</td>
            <td th:text="${cartItemEntry.value.amount}">36.8</td>
            <td><a href="">删除</a></td>
        </tr>

        </tbody>
    </table>
    <!--展示商品总数量、总金额-->
    <div class="footer">
        <div class="footer-left">
            <a href="#" class="clear-cart">清空购物车</a>
            <a href="#">继续购物</a>
        </div>

        <!--购物车为空-->
        <div class="footer-right" th:if="${session.existCart==null||session.existCart.totalCount==0}">
            <div>共<span>0</span>件商品</div>
            <div class="total-price">总金额<span>0.0</span>元</div>
            <a class="pay" href="checkout.html">去结账</a>
        </div>
        <!--购物车不为空-->
        <div class="footer-right" th:unless="${session.existCart==null||session.existCart.totalCount==0}">
            <div>共<span th:text="${session.existCart.totalCount}">3</span>件商品</div>
            <div class="total-price">总金额<span th:text="${session.existCart.totalAmount}">99.9</span>元</div>
            <a class="pay" href="checkout.html">去结账</a>
        </div>
    </div>
</div>

清空购物车

需求
- 在cart.html中，点击清空购物车按钮，将Session域中的Cart对象移除，从而实现清空购物车功能。
代码实现

<a th:href="@{/protected/cart(method=clearCart)}" class="clear-cart">清空购物车</a>

public void clearCart(HttpServletRequest request, HttpServletResponse response){
    request.getSession().removeAttribute(BookstoreConstant.SESSION_KEY_CART);
    //清空购物车完成，跳转到cart.html(重定向)
    try {
        //response.sendRedirect("/bookstore/protected/cart?method=toCartPage");
        System.out.println(request.getContextPath() + File.separator
                + request.getServletPath() + "?method=toCartPage");
        response.sendRedirect(request.getContextPath()
                + request.getServletPath() + "?method=toCartPage");
    } catch (IOException e) {
        e.printStackTrace();
    }
}

购物车项减一

需求
- 在cart.html中，点击减号按钮,如果当前购物车项数量为1时删除；如果当前购物车项数量大于1时减一。
代码实现

<a th:href="@{/protected/cart(method=cartItemCountDecrease,bookId=${cartItemEntry.key})}">
    -
</a>

/**
 * 指定购物车项数量减一
 * @param request
 * @param response
 */
public void cartItemCountDecrease(HttpServletRequest request, HttpServletResponse response){
    Integer bookId = Integer.parseInt(request.getParameter("bookId"));
    //获取指定bookId的购物车项数量
    Cart cart  = (Cart) request.getSession().getAttribute(BookstoreConstant.SESSION_KEY_CART);
    CartItem cartItem = cart.getCartItemMap().get(bookId);
    if (cartItem.getCount() <= 1) {
        //直接移除购物车项
        cart.removeCartItem(bookId);
    } else {
        //购物车项数量减一
        cart.cartItemCountDecrease(bookId);
    }
    //
    try {
        response.sendRedirect(request.getContextPath()
                + request.getServletPath() + "?method=toCartPage");
    } catch (IOException e) {
        e.printStackTrace();
    }

}

购物车项加一

需求
- 在cart.html中，点击加号按钮，在原有商品数量基础上加1
代码实现

<a th:href="@{/protected/cart(method=cartItemCountIncrease,bookId=${cartItemEntry.key})}">
    +
</a>

/**
 * 指定购物车项数量加一
 * @param request
 * @param response
 */
public void cartItemCountIncrease(HttpServletRequest request, HttpServletResponse response){
    Integer bookId = Integer.parseInt(request.getParameter("bookId"));
    //获取指定bookId的购物车项数量
    Cart cart  = (Cart) request.getSession().getAttribute(BookstoreConstant.SESSION_KEY_CART);
    cart.cartItemCountIncrease(bookId);
    //
    try {
        response.sendRedirect(request.getContextPath()
                + request.getServletPath() + "?method=toCartPage");
    } catch (IOException e) {
        e.printStackTrace();
    }

}

删除购物车项

需求
- 在cart.html中，点击删除按钮，删除指定购物车项
代码实现

<a th:href="@{/protected/cart(method=removeCartItem,bookId=${cartItemEntry.key})}">
    删除
</a>

public void removeCartItem(HttpServletRequest request, HttpServletResponse response){
    Integer bookId = Integer.parseInt(request.getParameter("bookId"));
    //获取指定bookId的购物车项数量
    Cart cart  = (Cart) request.getSession().getAttribute(BookstoreConstant.SESSION_KEY_CART);
    cart.removeCartItem(bookId);
    //
    try {
        response.sendRedirect(request.getContextPath()
                + request.getServletPath() + "?method=toCartPage");
    } catch (IOException e) {
        e.printStackTrace();
    }

}

修改购物车项数量

需求
- 在cart.html中，用户在文本框输入新数据后，根据用户输入修改购物车项数量
代码实现

<input class="count-num" type="text" th:value="${cartItemEntry.value.count}"
       @change="updateCartItemCount()"/>
<!--隐藏的input，value为bookId-->
<input type="hidden" th:value="${cartItemEntry.key}">

<script>

    var vue = new Vue({
        el: "#app",
        data: {},
        methods: {
            updateCartItemCount() {
                //console.log(bookId);//?
                var bookId = event.target.nextElementSibling.value;
                var newCount = event.target.value;
                console.log("newCount : " + newCount);
                if (newCount <= 0) {
                    location.href = "protected/cart?method=removeCartItem&bookId=" + bookId;
                } else {
                    //请求ProtectedCartServlet中的updateCartItemCount方法， 并传递bookId、newCount两个参数
                    location.href = "protected/cart?method=updateCartItemCount&bookId=" + bookId + "&newCount=" + newCount;
                }

            }
        }
    })

</script>

/**
 * 修改购物车项数量
 * @param request
 * @param response
 */
public void updateCartItemCount(HttpServletRequest request, HttpServletResponse response) {
    Integer bookId = Integer.parseInt(request.getParameter("bookId"));
    Integer newCount = Integer.parseInt(request.getParameter("newCount"));
    Cart cart = (Cart) request.getSession().getAttribute(BookstoreConstant.SESSION_KEY_CART);
    if (newCount <= 0) {
        //直接删除购物车项
        cart.removeCartItem(bookId);
    } else {
        //修改购物车项数量
        cart.updateCartItemCount(bookId, newCount);
    }
    try {
        response.sendRedirect(request.getContextPath()
                + request.getServletPath() + "?method=toCartPage");
    } catch (IOException e) {
        e.printStackTrace();
    }

}

BigDecimal精度调整

代码实现

public Double getAmount() {
    BigDecimal countBig = new BigDecimal(this.count + "");
    BigDecimal priceBig = new BigDecimal(this.price + "");
    this.amount = countBig.multiply(priceBig).doubleValue();
    return this.amount ;
}

public Double getTotalAmount() {
    Collection<CartItem> cartItems = cartItemMap.values();
    BigDecimal totalAmountBig = new BigDecimal(0.0 + "");
    for (CartItem cartItem : cartItems) {
        BigDecimal amountBig = new BigDecimal(cartItem.getAmount() + "");
        totalAmountBig = totalAmountBig.add(amountBig);

    }
    this.totalAmount = totalAmountBig.doubleValue();
    return this.totalAmount;
}