如何實(shí)現(xiàn)Javabean與JSP的購物車功能

本篇內(nèi)容介紹了“如何實(shí)現(xiàn)Javabean與JSP的購物車功能”的有關(guān)知識(shí)，在實(shí)際案例的操作過程中，不少人都會(huì)遇到這樣的困境，接下來就讓小編帶領(lǐng)大家學(xué)習(xí)一下如何處理這些情況吧！希望大家仔細(xì)閱讀，能夠?qū)W有所成！

首先呢，在買了東西之后要放在購物車?yán)铮?dāng)車子里的物品有相同時(shí)就疊加，不再創(chuàng)建物品對(duì)象，有了物品之后肯 定要有價(jià)格，數(shù)量等等對(duì)象。這些對(duì)象我們要封裝在JAVABEAN 中的！有了Javabean就需要建立SERVLET來進(jìn)行與業(yè)務(wù)層連接，我們就需要有，增加購物車，刪除購物車，清楚購物車等一系列的Servlet和SERVICE層連接！SERVICE層調(diào)用DAO層，這些步驟正體現(xiàn)出了MVC的設(shè)計(jì)模式！下面我們看具體的實(shí)現(xiàn)基于Javabean與JSP的購物車功能吧！

(1) 1. 代表購物車的ShoppingCart 類

public class ShoppingCart {   //裝載 ShoppingCartItem 的數(shù)據(jù)結(jié)構(gòu): Map, 鍵： 書的 id, 值: 書對(duì)應(yīng)的 ShoppingCartItem   private Map<String, ShoppingCartItem> books = null;      public ShoppingCart(){    books = new HashMap<String, ShoppingCartItem>();   }     public Map<String, ShoppingCartItem> getBooks() {    return books;   }      public Book getBook(String bookId){    Book book = null;        ShoppingCartItem sci = this.books.get(bookId);    if (sci == null)     return null;        return sci.getBook ();   }      public float getTotalPrice(){    float totalPrice = 0.0f;        //對(duì) books 中的 value 進(jìn)行遍歷, 取其 price 屬性的和     Iterator<ShoppingCartItem> iterator = books.values().iterator ();    while(iterator.hasNext()){     ShoppingCartItem sci = iterator.next();     totalPrice += sci.getPrice();    }         return totalPrice;   }      public int getTotalQuantity(){    int quantity = 0;        //對(duì) books 中的 value 進(jìn)行遍歷, 取其 quantity 屬性的和    Iterator<ShoppingCartItem> iterator = books.values().iterator();    while(iterator.hasNext()) {     ShoppingCartItem sci = iterator.next();     quantity += sci.getQuantity();    }        return quantity;   }       public boolean isExistInShoppingCart(String bookId){    return this.books.get(bookId) != null;   }      public ShoppingCartItem getShoppingCartItemByBookId(String bookId){    return this.books.get(bookId);   }       public void addNewItemToShoppingCart(ShoppingCartItem sci) {    this.books.put(sci.getBook().getId(), sci);   }  }

2. 代表購物車中的物品

public class ShoppingCartItem {   //具體指向某本書   private Book book;      //當(dāng)前商品在購物車中的數(shù)量   private int quantity;      public ShoppingCartItem(Book book) {    this.book = book;    this.quantity = 1;   }    //當(dāng)前商品的總價(jià)格   private float price;      public void incrementQuantity(){    this.quantity++;   }    public Book getBook() {    return book;   }    public void setBook(Book book) {    this.book = book;   }    public int getQuantity() {    return quantity;   }    public void setQuantity(int quantity) {    this.quantity = quantity;   }     public float getPrice() {    return this.book.getPrice() * this.quantity;   }   }

(2)建立DAO,此時(shí)有人會(huì)問，這次DAO為什么沒有購物車呢，因?yàn)橘徫镘囀菦]有數(shù)據(jù)的，而是里面的物品才有 數(shù)據(jù)的，當(dāng)有更新購物車?yán)锩娴奈锲窌r(shí)才會(huì)早DAO里面寫方法！

public class BookDAO {      //   public void upadateBookQuantityByBookId(Connection conn, String bookId, int quantity){    String sql = "UPDATE books SET saleAmount = saleAmount + ? WHERE id = ?";    Object [] params = new Object[]{quantity, bookId};        QueryRunner queryRunner = new QueryRunner ();        try {     queryRunner.update(conn, sql, params);    } catch (SQLException e) {     // TODO Auto-generated catch block     e.printStackTrace();     throw new RuntimeException (MyBookStoreConstants.UPDATE_BOOK_SALEAMOUNT_BY_BOOK_ID_EXCEPTION);    }   }

(3) 建立業(yè)務(wù)層,涉及到添加，清空等方法！這邊佟剛老師的代碼都有詳細(xì)的解釋！

public class BookService {   //根據(jù)給定的 ShoppingCart 對(duì)象, 調(diào)用 DAO 方法進(jìn)行數(shù)據(jù)庫更新操作   public void buyBooks(ShoppingCart sc){    //對(duì) sc 中的 ShoppingCartItem 對(duì)象進(jìn)行遍歷, 調(diào)用 BookDAO.upadateBookQuantityByBookId 方法    Connection conn = null;    conn = DBHelper.getConnection();        try {     Iterator<ShoppingCartItem> shoppingCartItemSet = sc.getBooks().values ().iterator();     BookDAO bookDAO = new BookDAO ();          while(shoppingCartItemSet.hasNext()) {      ShoppingCartItem sci = shoppingCartItemSet.next ();            String bookId = sci.getBook().getId ();      int quantity = sci.getQuantity ();            bookDAO.upadateBookQuantityByBookId(conn, bookId, quantity);     }    }finally {     DBHelper.releaseDBSource(null, null, conn);    }            }      //參數(shù) items 中的鍵為 書的 id 號(hào), 值為購 物車中對(duì)應(yīng)的 數(shù)量   public void updateShoppingCart(Map<String,Integer> items, ShoppingCart sc){    Set<String> keySet = null;    keySet = items.keySet ();        for(Iterator<String> it = keySet.iterator(); it.hasNext(); ) {     String bookId = it.next();     int quantity = items.get (bookId);          if(quantity <= 0) {      sc.getBooks().remove(bookId);     }else {      sc.getShoppingCartItemByBookId(bookId).setQuantity (quantity);     }          }   }       //清空購物車   public void clearShoppingCart(ShoppingCart sc) {    sc.getBooks().clear();   }      public void deleteShoppingCartItemById(String id, ShoppingCart sc){    //刪除 sc 中的 id 元素     sc.getBooks().remove(id);   }      //把 id 對(duì)應(yīng)的 ShoppingCartItem 對(duì)象放入購物車 ShoppingCart 對(duì)象中   public void addToShoppingCart(String id, ShoppingCart sc) {        //1. 查看 sc 中有沒有 id 對(duì)應(yīng)的 ShoppingCartItem 對(duì)象     if(sc.isExistInShoppingCart(id)){     //1.1 有: 把該對(duì)象取出, 使其數(shù)量 + 1, 調(diào)用 sci.increseQuantity(); 方法     ShoppingCartItem scsci = sc.getShoppingCartItemByBookId(id);     sci.incrementQuantity();    }     //1.2 沒有: 創(chuàng)建一個(gè)新的 ShoppingCartItem 對(duì)象, 并將其放入 sc 中, 以書的 id 作為鍵     else{     //1.2.1 根據(jù) id 獲取相應(yīng)的 Book 對(duì)象, 調(diào)用 BookDAO 的 selectBookByBookId() 方法     Book book = null;     BookDAO bookDAO = null;          bookDAO = new BookDAO();     book = bookDAO.selectBookByBookId(id);          ShoppingCartItem sci = null;     sci = new ShoppingCartItem (book);          sc.addNewItemToShoppingCart(sci);    }    }  }

(4)這段是 檢查購物車是有對(duì)象的，這里單獨(dú)拿出來是可以很好的在WEB開發(fā)中很好的進(jìn)行重用 的。

public class MyBookStoreUtils {   private MyBookStoreUtils(){}      public static  ShoppingCart getShppingCartForCreateOrExist(HttpServletRequest request) {    ShoppingCart sc = null;    //2.1 檢查在 HttpSession 對(duì)象中有沒有購物車對(duì)象 , 即檢查 session 中是否有 MyBookStoreConstants.SHOOPING_CART_KEY 屬性    //   若 已經(jīng)存在, 說明購物車存在, 直接取出    HttpSession session = null;    session = request.getSession();        Object obj = session.getAttribute (MyBookStoreConstants.SHOOPING_CART_KEY);        if(obj != null) {     sc = (ShoppingCart) obj;    }    //2.2 若不存在 MyBookStoreConstants.SHOOPING_CART_KEY 屬性, 創(chuàng)建一個(gè)購物車對(duì)象, 并把該對(duì)象放入 Session 中     else{     sc = new ShoppingCart ();     session.setAttribute(MyBookStoreConstants.SHOOPING_CART_KEY, sc);    }        return sc;   }      public static  ShoppingCart getShppingCartForExist(HttpServletRequest request) {    ShoppingCart sc = null;    //2.1 檢查在 HttpSession 對(duì)象中有沒有購物車對(duì)象 , 即檢查 session 中是否有 MyBookStoreConstants.SHOOPING_CART_KEY 屬性    //   若 已經(jīng)存在, 說明購物車存在, 直接取出    HttpSession session = null;    session = request.getSession();        Object obj = session.getAttribute (MyBookStoreConstants.SHOOPING_CART_KEY);        if(obj != null) {     sc = (ShoppingCart) obj;    }    //2.2 若不存在 MyBookStoreConstants.SHOOPING_CART_KEY 屬性, 拋出異常, 提示用戶還不存在購物車.    else {     throw new RuntimeException (MyBookStoreConstants.NO_SHOPPING_CART_EXCETPION);    }         return sc;   }  }

(5)這里是所有與購物車相關(guān)的SERVLET.

這個(gè)是更新數(shù)據(jù)的，需要在SERVICE中調(diào)用DAO的!

public class UpdateShoppingCartServlet extends HttpServlet {    public void doPost(HttpServletRequest request, HttpServletResponse response)      throws ServletException, IOException {    //獲取表單信息     // request.getParameter(""); 方法行不通,　因?yàn)楸韱蔚摹ame 是隨時(shí)變化的         //獲取表單中的所有 name    Enumeration<String> nameEnums = request.getParameterNames();        Map items = new HashMap<String, Integer>();    //遍歷 nameEnums, 再取出對(duì)應(yīng)的 Value, 封裝到 items 中         try {     while(nameEnums.hasMoreElements()) {      String bookId = nameEnums.nextElement();      String quantity = request.getParameter (bookId);            items.put(bookId, Integer.parseInt (quantity));     }    } catch (NumberFormatException e) {     // TODO Auto-generated catch block     e.printStackTrace ();     throw new RuntimeException (MyBookStoreConstants.QUANTITY_FORMAT_EXCEPTION);    }        //獲 取購物車對(duì)象    ShoppingCart sc = null;    sc = MyBookStoreUtils.getShppingCartForExist(request);        //調(diào)用 Service 方法     BookService bookService = new BookService ();    bookService.updateShoppingCart(items, sc);        //派發(fā)頁面 : showShoppingCart.jsp 頁面    String forwardPage = "/WEB- INF/jsp/showShoppingCart.jsp";    request.getRequestDispatcher(forwardPage).forward (request, response);   }   }   public class ShowShoppingCartServlet extends HttpServlet {    public void doGet(HttpServletRequest request, HttpServletResponse response)      throws ServletException, IOException {    //做一個(gè)轉(zhuǎn)發(fā)     String forwardPage = null;        forwardPage = "/WEB- INF/jsp/showShoppingCart.jsp";        RequestDispatcher dispatcher = null;    dispatcher = request.getRequestDispatcher (forwardPage);    dispatcher.forward(request, response);   }   }  public class ReceiptServlet extends HttpServlet {    public void doPost(HttpServletRequest request, HttpServletResponse response)      throws ServletException, IOException {    //1. 獲取表單信息: name 和 cardId        //2. 調(diào)用 Service 方法, 更新 books 表各條 book 的 saleAmount 字段         //2.1 獲取購物車    ShoppingCart sc = MyBookStoreUtils.getShppingCartForExist(request);        BookService bookService = new BookService();    bookService.buyBooks (sc);        //2.1 使 Session 失效    HttpSession session = null;    session = request.getSession();    session.invalidate ();        //3. 派發(fā)頁面: receipt.jsp 頁面     request.getRequestDispatcher("/WEB-INF/jsp/receipt.jsp").forward(request, response);    }  }

這段我先開始很納悶老師為什么會(huì)這樣寫呢，其實(shí)很簡(jiǎn)單，寫個(gè)專門的轉(zhuǎn)發(fā)的SERVLET這樣，在每次轉(zhuǎn)發(fā)的時(shí)候就只連接一個(gè)servlet比連接多個(gè)更來的簡(jiǎn)潔！提高了效率！

public class ForwardServlet extends HttpServlet {    public void doGet(HttpServletRequest request, HttpServletResponse response)      throws ServletException, IOException {    //1. 獲取 path    String path = request.getParameter("path");        //2. 派 發(fā)頁面    request.getRequestDispatcher(path).forward(request, response);   }   }  public class DeleteShoppingCartItemServlet extends HttpServlet {    public void doGet(HttpServletRequest request, HttpServletResponse response)      throws ServletException, IOException {    //1. 獲取 id 號(hào)     String id = request.getParameter("bookid");        //2. 調(diào)用 BookService 方法 deleteShoppingCartItemById：, 進(jìn)行刪除操作    ShoppingCart sc = MyBookStoreUtils.getShppingCartForExist(request);        String bookTitle = sc.getBook(id).getTitle();        BookService bookService = new BookService ();    bookService.deleteShoppingCartItemById(id, sc);        //3. 派發(fā)頁面    request.setAttribute(MyBookStoreConstants.DELETE_FROM_SHOPPING_CART_BOOK_TITLE, bookTitle);        String forwardPage = "/WEB- INF/jsp/showShoppingCart.jsp";    //4. 判斷購物車是否為空,　若為空則派發(fā)到　emptyCart.jsp 頁面    if(sc.getBooks().isEmpty())     forwardPage = "/WEB- INF/jsp/emptyCart.jsp";        RequestDispatcher dispatcher = null;    dispatcher = request.getRequestDispatcher (forwardPage);    dispatcher.forward(request, response);   }   }

這里是清空購物車的SERVLET.

public class ClearShoppingCartServlet extends HttpServlet {    public void doGet(HttpServletRequest request, HttpServletResponse response)      throws ServletException, IOException {    //1. 調(diào)用方法     BookService bookService = new BookService ();        ShoppingCart sc = null;    sc = MyBookStoreUtils.getShppingCartForExist (request);        bookService.clearShoppingCart (sc);        //2. 派發(fā)頁面    String forwardPage = null;    forwardPage = "/WEB- INF/jsp/emptyCart.jsp";        RequestDispatcher dispatcher = request.getRequestDispatcher(forwardPage);    dispatcher.forward(request, response);   }   }  public class AddToShoppingCartServlet extends HttpServlet {    public void doGet(HttpServletRequest request, HttpServletResponse response)      throws ServletException, IOException {            //1. 獲取書的 id 號(hào)    String bookId = null;    bookId = request.getParameter("bookId");        //2. 獲取 購物車對(duì)象: 調(diào)用 getShppingCart 方法    ShoppingCart sc = null;    sc = MyBookStoreUtils.getShppingCartForCreateOrExist(request);        //3. 調(diào)用 Service 方法把 id 對(duì)應(yīng)的 ShoppingCartItem 對(duì)象放入購物車 ShoppingCart 對(duì)象中： addToShoppingCart(id, shoppingCart);    BookService bookService = null;    bookService = new BookService();        bookService.addToShoppingCart(bookId, sc);        //4. 派發(fā)頁面    String forwardPage = "/index.jsp";        //4.1 獲取書名    String bookTitle = null;    //bookTitle = sc.getBooks().get(bookId).getBook().getTitle ();    bookTitle = sc.getBook(bookId).getTitle();        //4.2 將書 名放入請(qǐng)求域中, 以讓頁面進(jìn)行顯示    request.setAttribute (MyBookStoreConstants.ADD_TO_SHOPPING_CART_BOOK_TITLE, bookTitle);        RequestDispatcher dispatcher = null;    dispatcher = request.getRequestDispatcher (forwardPage);    dispatcher.forward(request, response);   }   }

(6)下面是顯示層，對(duì)應(yīng)著其相應(yīng)的SERVLET.下面的JSP頁面運(yùn)用到了我們前段時(shí)間學(xué)的JSTL，EL表示.
'cashier.jsp'

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"% >  <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html>   <head>     <title>My JSP 'cashier.jsp' starting page</title>   </head>      <body>     <center>      <br><br>      您一共購買 了 ${sessionScope.shoppingcartkey.totalQuantity} 本書       <br><br>      您應(yīng)付金額 是:${sessionScope.shoppingcartkey.totalPrice} 元。       <br><br>      <form action="receiptServlet" method="POST">       <table>        <tr>         <td>信用卡用戶 名:</td>         <td><input type="text" name="userName"/></td>        </tr>        <tr>         <td>信用卡帳號(hào):</td>         <td><input type="text" name="cardId"/></td>                 </tr>        <tr align="center">         <td colspan="2">          <input type="submit" value="遞交 "/>         </td>        </tr>       </table>      </form>     </center>   </body> </html>  'receipt.jsp'  <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>  <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html>   <head>     <title>My JSP 'emptyCart.jsp' starting page</title>   </head>      <body>     <center>      <br><br>      您的購物車 為空<br><br>      <a href="${pageContext.request.contextPath }/index.jsp">繼續(xù)購物<a>     </center>   </body> </html> <%@ page language="java" import="java.util.*" pageEncoding="UTF- 8"%>  <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html>   <head>     <title>My JSP 'receipt.jsp' starting page</title>   </head>      <body>     再見: ${param.userName }<br><br>    <a href="${pageContext.request.contextPath }/index.jsp">繼續(xù)購物</a>&nbsp;&nbsp;    </body> </html>  'showShoppingCart.jsp'  <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"% > <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>  <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html>   <head>     <title>My JSP 'showShoppingCart.jsp' starting page</title>   </head>      <body>     <center>      <c:if test="${requestScope.deleteToShoppingCartBookTitle != null}">       <br><br>        您已經(jīng)把 ${requestScope.deleteToShoppingCartBookTitle} 從購物車中刪除了！       </c:if>      <br><br>        您的購物車中一共有 ${sessionScope.shoppingcartkey.totalQuantity} 本書       <br><br>      <form action="updateShoppingCartServlet" method="POST">       <table cellpadding="10" cellspacing="0">        <tr>         <th>書名</th>         <th>價(jià) 格</th>         <th>數(shù)量 </th>         <td></td>        </tr>        <c:forEach items="${sessionScope.shoppingcartkey.books}" var="sci">         <tr>          <td>${sci.value.book.title }</td>          <td>${sci.value.book.price }</td>          <td><input type="text" value="${sci.value.quantity }" name="${sci.key }" size="2" /></td>          <td><a href="${pageContext.request.contextPath }/deleteShoppingCartItemServlet?bookid=${sci.key }">刪除 </a></td>         <td></td>        </tr>        </c:forEach>       </table>       <input type="submit" value="保存修 改">      </form>      <br>      總價(jià)格： ${sessionScope.shoppingcartkey.totalPrice}        <br><br>      <a href="${pageContext.request.contextPath }/index.jsp">繼續(xù)購物 </a>&nbsp;&nbsp;       <a href="${pageContext.request.contextPath }/clearShoppingCartServlet">清空購物車 </a>&nbsp;&nbsp;       <a href="${pageContext.request.contextPath }/forwardServlet?path=cashier.jsp">付賬 </a>     </center>   </body> </html>

“如何實(shí)現(xiàn)Javabean與JSP的購物車功能”的內(nèi)容就介紹到這里了，感謝大家的閱讀。如果想了解更多行業(yè)相關(guān)的知識(shí)可以關(guān)注億速云網(wǎng)站，小編將為大家輸出更多高質(zhì)量的實(shí)用文章！