Java 会话跟踪CoreServlet购物车示例
我正在学习Marty Hall的“核心servlet和JavaServer页面”。我试图学习第9章第节中“使用购物车和会话跟踪的在线商店”的示例。4. 我已经下载并编译了所有代码。我试图使其运行，但收到HTTP状态404-/OrderPage 类型状态报告 消息/订单页 说明请求的资源不可用 ApacheTomcat/7.0.34 我试图通过在order page servlet中添加@WebServlet（“OrderPage”）来解决这个问题，但这并不能解决这个问题。那么，有什么想法会导致这个问题吗Java 会话跟踪CoreServlet购物车示例,java,session,servlets,Java,Session,Servlets,我正在学习Marty Hall的“核心servlet和JavaServer页面”。我试图学习第9章第节中“使用购物车和会话跟踪的在线商店”的示例。4. 我已经下载并编译了所有代码。我试图使其运行，但收到HTTP状态404-/OrderPage 类型状态报告 消息/订单页 说明请求的资源不可用 ApacheTomcat/7.0.34 我试图通过在order page servlet中添加@WebServlet（“OrderPage”）来解决这个问题，但这并不能解决这个问题。那么，有什么想法会导致这
1. CatalogPage.java
package coreservlets;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;
/** Base class for pages showing catalog entries.
* Servlets that extend this class must specify
* the catalog entries that they are selling and the page
* title <I>before</I> the servlet is ever accessed. This
* is done by putting calls to setItems and setTitle
* in init.
* <P>
* Taken from Core Servlets and JavaServer Pages
* from Prentice Hall and Sun Microsystems Press,
* http://www.coreservlets.com/.
* © 2000 Marty Hall; may be freely used or adapted.
*/
public abstract class CatalogPage extends HttpServlet {
private Item[] items;
private String[] itemIDs;
private String title;
/** Given an array of item IDs, look them up in the
* Catalog and put their corresponding Item entry
* into the items array. The Item contains a short
* description, a long description, and a price,
* using the item ID as the unique key.
* <P>
* Servlets that extend CatalogPage <B>must</B> call
* this method (usually from init) before the servlet
* is accessed.
*/
protected void setItems(String[] itemIDs) {
this.itemIDs = itemIDs;
items = new Item[itemIDs.length];
for(int i=0; i<items.length; i++) {
items[i] = Catalog.getItem(itemIDs[i]);
}
}
/** Sets the page title, which is displayed in
* an H1 heading in resultant page.
* <P>
* Servlets that extend CatalogPage <B>must</B> call
* this method (usually from init) before the servlet
* is accessed.
*/
protected void setTitle(String title) {
this.title = title;
}
/** First display title, then, for each catalog item,
* put its short description in a level-two (H2) heading
* with the price in parentheses and long description
* below. Below each entry, put an order button
* that submits info to the OrderPage servlet for
* the associated catalog entry.
* <P>
* To see the HTML that results from this method, do
* "View Source" on KidsBooksPage or TechBooksPage, two
* concrete classes that extend this abstract class.
*/
public void doGet(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html");
if (items == null) {
response.sendError(response.SC_NOT_FOUND,
"Missing Items.");
return;
}
PrintWriter out = response.getWriter();
out.println(ServletUtilities.headWithTitle(title) +
"<BODY BGCOLOR=\"#FDF5E6\">\n" +
"<H1 ALIGN=\"CENTER\">" + title + "</H1>");
Item item;
for(int i=0; i<items.length; i++) {
out.println("<HR>");
item = items[i];
// Show error message if subclass lists item ID
// that's not in the catalog.
if (item == null) {
out.println("<FONT COLOR=\"RED\">" +
"Unknown item ID " + itemIDs[i] +
"</FONT>");
} else {
out.println();
String formURL =
"/servlet/coreservlets.OrderPage";
// Pass URLs that reference own site through encodeURL.
formURL = response.encodeURL(formURL);
out.println
("<FORM ACTION=\"" + formURL + "\">\n" +
"<INPUT TYPE=\"HIDDEN\" NAME=\"itemID\" " +
" VALUE=\"" + item.getItemID() + "\">\n" +
"<H2>" + item.getShortDescription() +
" ($" + item.getCost() + ")</H2>\n" +
item.getLongDescription() + "\n" +
"<P>\n<CENTER>\n" +
"<INPUT TYPE=\"SUBMIT\" " +
"VALUE=\"Add to Shopping Cart\">\n" +
"</CENTER>\n<P>\n</FORM>");
}
}
out.println("<HR>\n</BODY></HTML>");
}
/** POST and GET requests handled identically. */
public void doPost(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
2. KidsBookPage.java
package coreservlets;
/** A specialization of the CatalogPage servlet that
* displays a page selling three famous kids-book series.
* Orders are sent to the OrderPage servlet.
* <P>
* Taken from Core Servlets and JavaServer Pages
* from Prentice Hall and Sun Microsystems Press,
* http://www.coreservlets.com/.
* © 2000 Marty Hall; may be freely used or adapted.
*/
public class KidsBooksPage extends CatalogPage {
public void init() {
String[] ids = { "lewis001", "alexander001", "rowling001" };
setItems(ids);
setTitle("All-Time Best Children's Fantasy Books");
}
}
3. TechBooksPage.java
package coreservlets;
/** A specialization of the CatalogPage servlet that
* displays a page selling two famous computer books.
* Orders are sent to the OrderPage servlet.
* <P>
* Taken from Core Servlets and JavaServer Pages
* from Prentice Hall and Sun Microsystems Press,
* http://www.coreservlets.com/.
* © 2000 Marty Hall; may be freely used or adapted.
*/
public class TechBooksPage extends CatalogPage {
public void init() {
String[] ids = { "hall001", "hall002" };
setItems(ids);
setTitle("All-Time Best Computer Books");
}
}
4. OrderPage.java
package coreservlets;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;
import java.text.NumberFormat;
/** Shows all items currently in ShoppingCart. Clients
* have their own session that keeps track of which
* ShoppingCart is theirs. If this is their first visit
* to the order page, a new shopping cart is created.
* Usually, people come to this page by way of a page
* showing catalog entries, so this page adds an additional
* item to the shopping cart. But users can also
* bookmark this page, access it from their history list,
* or be sent back to it by clicking on the "Update Order"
* button after changing the number of items ordered.
* <P>
* Taken from Core Servlets and JavaServer Pages
* from Prentice Hall and Sun Microsystems Press,
* http://www.coreservlets.com/.
* © 2000 Marty Hall; may be freely used or adapted.
*/
public class OrderPage extends HttpServlet {
public void doGet(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException {
HttpSession session = request.getSession(true);
ShoppingCart cart;
synchronized(session) {
cart = (ShoppingCart)session.getValue("shoppingCart");
// New visitors get a fresh shopping cart.
// Previous visitors keep using their existing cart.
if (cart == null) {
cart = new ShoppingCart();
session.putValue("shoppingCart", cart);
}
String itemID = request.getParameter("itemID");
if (itemID != null) {
String numItemsString =
request.getParameter("numItems");
if (numItemsString == null) {
// If request specified an ID but no number,
// then customers came here via an "Add Item to Cart"
// button on a catalog page.
cart.addItem(itemID);
} else {
// If request specified an ID and number, then
// customers came here via an "Update Order" button
// after changing the number of items in order.
// Note that specifying a number of 0 results
// in item being deleted from cart.
int numItems;
try {
numItems = Integer.parseInt(numItemsString);
} catch(NumberFormatException nfe) {
numItems = 1;
}
cart.setNumOrdered(itemID, numItems);
}
}
}
// Whether or not the customer changed the order, show
// order status.
response.setContentType("text/html");
PrintWriter out = response.getWriter();
String title = "Status of Your Order";
out.println(ServletUtilities.headWithTitle(title) +
"<BODY BGCOLOR=\"#FDF5E6\">\n" +
"<H1 ALIGN=\"CENTER\">" + title + "</H1>");
synchronized(session) {
Vector itemsOrdered = cart.getItemsOrdered();
if (itemsOrdered.size() == 0) {
out.println("<H2><I>No items in your cart...</I></H2>");
} else {
// If there is at least one item in cart, show table
// of items ordered.
out.println
("<TABLE BORDER=1 ALIGN=\"CENTER\">\n" +
"<TR BGCOLOR=\"#FFAD00\">\n" +
" <TH>Item ID<TH>Description\n" +
" <TH>Unit Cost<TH>Number<TH>Total Cost");
ItemOrder order;
// Rounds to two decimal places, inserts dollar
// sign (or other currency symbol), etc., as
// appropriate in current Locale.
NumberFormat formatter =
NumberFormat.getCurrencyInstance();
String formURL =
"/OrderPage";
// Pass URLs that reference own site through encodeURL.
formURL = response.encodeURL(formURL);
// For each entry in shopping cart, make
// table row showing ID, description, per-item
// cost, number ordered, and total cost.
// Put number ordered in textfield that user
// can change, with "Update Order" button next
// to it, which resubmits to this same page
// but specifying a different number of items.
for(int i=0; i<itemsOrdered.size(); i++) {
order = (ItemOrder)itemsOrdered.elementAt(i);
out.println
("<TR>\n" +
" <TD>" + order.getItemID() + "\n" +
" <TD>" + order.getShortDescription() + "\n" +
" <TD>" +
formatter.format(order.getUnitCost()) + "\n" +
" <TD>" +
"<FORM ACTION=\"" + formURL + "\">\n" +
"<INPUT TYPE=\"HIDDEN\" NAME=\"itemID\"\n" +
" VALUE=\"" + order.getItemID() + "\">\n" +
"<INPUT TYPE=\"TEXT\" NAME=\"numItems\"\n" +
" SIZE=3 VALUE=\"" +
order.getNumItems() + "\">\n" +
"<SMALL>\n" +
"<INPUT TYPE=\"SUBMIT\"\n "+
" VALUE=\"Update Order\">\n" +
"</SMALL>\n" +
"</FORM>\n" +
" <TD>" +
formatter.format(order.getTotalCost()));
}
String checkoutURL =
response.encodeURL("/Checkout.html");
// "Proceed to Checkout" button below table
out.println
("</TABLE>\n" +
"<FORM ACTION=\"" + checkoutURL + "\">\n" +
"<BIG><CENTER>\n" +
"<INPUT TYPE=\"SUBMIT\"\n" +
" VALUE=\"Proceed to Checkout\">\n" +
"</CENTER></BIG></FORM>");
}
out.println("</BODY></HTML>");
}
}
/** POST and GET requests handled identically. */
public void doPost(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
5. ShoppingCart.java
package coreservlets;
import java.util.*;
/** A shopping cart data structure used to track orders.
* The OrderPage servlet associates one of these carts
* with each user session.
* <P>
* Taken from Core Servlets and JavaServer Pages
* from Prentice Hall and Sun Microsystems Press,
* http://www.coreservlets.com/.
* © 2000 Marty Hall; may be freely used or adapted.
*/
public class ShoppingCart {
private Vector itemsOrdered;
/** Builds an empty shopping cart. */
public ShoppingCart() {
itemsOrdered = new Vector();
}
/** Returns Vector of ItemOrder entries giving
* Item and number ordered.
*/
public Vector getItemsOrdered() {
return(itemsOrdered);
}
/** Looks through cart to see if it already contains
* an order entry corresponding to item ID. If it does,
* increments the number ordered. If not, looks up
* Item in catalog and adds an order entry for it.
*/
public synchronized void addItem(String itemID) {
ItemOrder order;
for(int i=0; i<itemsOrdered.size(); i++) {
order = (ItemOrder)itemsOrdered.elementAt(i);
if (order.getItemID().equals(itemID)) {
order.incrementNumItems();
return;
}
}
ItemOrder newOrder = new ItemOrder(Catalog.getItem(itemID));
itemsOrdered.addElement(newOrder);
}
/** Looks through cart to find order entry corresponding
* to item ID listed. If the designated number
* is positive, sets it. If designated number is 0
* (or, negative due to a user input error), deletes
* item from cart.
*/
public synchronized void setNumOrdered(String itemID,
int numOrdered) {
ItemOrder order;
for(int i=0; i<itemsOrdered.size(); i++) {
order = (ItemOrder)itemsOrdered.elementAt(i);
if (order.getItemID().equals(itemID)) {
if (numOrdered <= 0) {
itemsOrdered.removeElementAt(i);
} else {
order.setNumItems(numOrdered);
}
return;
}
}
ItemOrder newOrder =
new ItemOrder(Catalog.getItem(itemID));
itemsOrdered.addElement(newOrder);
}
}
6. Item.java
package coreservlets;
/** Describes a catalog item for on-line store. The itemID
* uniquely identifies the item, the short description
* gives brief info like the book title and author,
* the long description describes the item in a couple
* of sentences, and the cost gives the current per-item price.
* Both the short and long descriptions can contain HTML
* markup.
* <P>
* Taken from Core Servlets and JavaServer Pages
* from Prentice Hall and Sun Microsystems Press,
* http://www.coreservlets.com/.
* © 2000 Marty Hall; may be freely used or adapted.
*/
public class Item {
private String itemID;
private String shortDescription;
private String longDescription;
private double cost;
public Item(String itemID, String shortDescription,
String longDescription, double cost) {
setItemID(itemID);
setShortDescription(shortDescription);
setLongDescription(longDescription);
setCost(cost);
}
public String getItemID() {
return(itemID);
}
protected void setItemID(String itemID) {
this.itemID = itemID;
}
public String getShortDescription() {
return(shortDescription);
}
protected void setShortDescription(String shortDescription) {
this.shortDescription = shortDescription;
}
public String getLongDescription() {
return(longDescription);
}
protected void setLongDescription(String longDescription) {
this.longDescription = longDescription;
}
public double getCost() {
return(cost);
}
protected void setCost(double cost) {
this.cost = cost;
}
}
7. ItemOrder.java
package coreservlets;
/** Associates a catalog Item with a specific order by
* keeping track of the number ordered and the total price.
* Also provides some convenience methods to get at the
* Item data without first extracting the Item separately.
* <P>
* Taken from Core Servlets and JavaServer Pages
* from Prentice Hall and Sun Microsystems Press,
* http://www.coreservlets.com/.
* © 2000 Marty Hall; may be freely used or adapted.
*/
public class ItemOrder {
private Item item;
private int numItems;
public ItemOrder(Item item) {
setItem(item);
setNumItems(1);
}
public Item getItem() {
return(item);
}
protected void setItem(Item item) {
this.item = item;
}
public String getItemID() {
return(getItem().getItemID());
}
public String getShortDescription() {
return(getItem().getShortDescription());
}
public String getLongDescription() {
return(getItem().getLongDescription());
}
public double getUnitCost() {
return(getItem().getCost());
}
public int getNumItems() {
return(numItems);
}
public void setNumItems(int n) {
this.numItems = n;
}
public void incrementNumItems() {
setNumItems(getNumItems() + 1);
}
public void cancelOrder() {
setNumItems(0);
}
public double getTotalCost() {
return(getNumItems() * getUnitCost());
}
}
8. Catalog.java
package coreservlets;
/** A catalog listing the items available in inventory.
* <P>
* Taken from Core Servlets and JavaServer Pages
* from Prentice Hall and Sun Microsystems Press,
* http://www.coreservlets.com/.
* © 2000 Marty Hall; may be freely used or adapted.
*/
public class Catalog {
// This would come from a database in real life
private static Item[] items =
{ new Item("hall001",
"<I>Core Servlets and JavaServer Pages</I> " +
" by Marty Hall",
"The definitive reference on servlets " +
"and JSP from Prentice Hall and \n" +
"Sun Microsystems Press. Nominated for " +
"the Nobel Prize in Literature.",
39.95),
new Item("hall002",
"<I>Core Web Programming, Java2 Edition</I> " +
"by Marty Hall, Larry Brown, and " +
"Paul McNamee",
"One stop shopping for the Web programmer. " +
"Topics include \n" +
"<UL><LI>Thorough coverage of Java 2; " +
"including Threads, Networking, Swing, \n" +
"Java2D, and Collections\n" +
"<LI>A fast introduction to HTML 4.01, " +
"including frames, style sheets, layers,\n" +
"and Netscape and Internet Explorer " +
"extensions.\n" +
"<LI>A fast introduction to HTTP 1.1, " +
"servlets, and JavaServer Pages.\n" +
"<LI>A quick overview of JavaScript 1.2\n" +
"</UL>",
49.95),
new Item("lewis001",
"<I>The Chronicles of Narnia</I> by C.S. Lewis",
"The classic children's adventure pitting " +
"Aslan the Great Lion and his followers\n" +
"against the White Witch and the forces " +
"of evil. Dragons, magicians, quests, \n" +
"and talking animals wound around a deep " +
"spiritual allegory. Series includes\n" +
"<I>The Magician's Nephew</I>,\n" +
"<I>The Lion, the Witch and the " +
"Wardrobe</I>,\n" +
"<I>The Horse and His Boy</I>,\n" +
"<I>Prince Caspian</I>,\n" +
"<I>The Voyage of the Dawn " +
"Treader</I>,\n" +
"<I>The Silver Chair</I>, and \n" +
"<I>The Last Battle</I>.",
19.95),
new Item("alexander001",
"<I>The Prydain Series</I> by Lloyd Alexander",
"Humble pig-keeper Taran joins mighty " +
"Lord Gwydion in his battle against\n" +
"Arawn the Lord of Annuvin. Joined by " +
"his loyal friends the beautiful princess\n" +
"Eilonwy, wannabe bard Fflewddur Fflam," +
"and furry half-man Gurgi, Taran discovers " +
"courage, nobility, and other values along\n" +
"the way. Series includes\n" +
"<I>The Book of Three</I>,\n" +
"<I>The Black Cauldron</I>,\n" +
"<I>The Castle of Llyr</I>,\n" +
"<I>Taran Wanderer</I>, and\n" +
"<I>The High King</I>.",
19.95),
new Item("rowling001",
"<I>The Harry Potter Trilogy</I> by " +
"J.K. Rowling",
"The first three of the popular stories " +
"about wizard-in-training Harry Potter\n" +
"topped both the adult and children's " +
"best-seller lists. Series includes\n" +
"<I>Harry Potter and the " +
"Sorcerer's Stone</I>,\n" +
"<I>Harry Potter and the " +
"Chamber of Secrets</I>, and\n" +
"<I>Harry Potter and the " +
"Prisoner of Azkaban</I>.",
25.95)
};
public static Item getItem(String itemID) {
Item item;
if (itemID == null) {
return(null);
}
for(int i=0; i<items.length; i++) {
item = items[i];
if (itemID.equals(item.getItemID())) {
return(item);
}
}
return(null);
}
}
9. CheckOut.html
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
<HEAD>
<TITLE>Checkout</TITLE>
</HEAD>
<BODY BGCOLOR="#FDF5E6">
<H2 ALIGN="CENTER">Checkout</H2>
We're sorry, but we are unable to handle credit card orders
at this time. Please make out a check to Marty Hall,
Research and Technology Development Center, Johns Hopkins
Applied Physics Lab, 11100 Johns Hopkins Rd.,
Laurel, MD 20723.
<P>
To expedite your order, please do <I>not</I> fill in the amount.
I'll do that after I decide where I want to take my next
vacation.
</BODY>
</HTML>
1。CatalogPage.java
包coreservlet；
导入java.io.*；
导入javax.servlet.*；
导入javax.servlet.http.*；
导入java.util.*；
/**显示目录项的页面的基类。
*扩展此类的servlet必须指定
*他们正在销售的目录条目和页面
*在访问servlet之前的标题。这
*通过调用setItems和setTitle来完成
*在init中。
*
*取自核心servlet和JavaServer页面
*来自普伦蒂斯大厅和太阳微系统出版社，
* http://www.coreservlets.com/.
*&复制；2000年马蒂厅；可以自由使用或改编。
*/
公共抽象类CatalogPage扩展了HttpServlet{
私人物品[]项；
私有字符串[]itemIDs；
私有字符串标题；
/**给定一个项目ID数组，在
*编目并放入相应的项目条目
*进入items数组。该项包含一个
*描述、详细描述和价格，
*使用项目ID作为唯一键。
*
*扩展CatalogPage的servlet必须调用
*此方法（通常来自init）在servlet之前
*访问。
*/
受保护的无效集合项（字符串[]项ID）{
this.itemIDs=itemIDs；
items=新项目[ItemId.length]；
对于（inti=0；i您使用哪个版本的servlet？
如果2.5或更低版本，则不支持批注。您需要在web-INF中创建web.xml文件，并设置如下：
<servlet>
<servlet-name>SecondServlet</servlet-name>
<servlet-class>ru.bmstu.SecondServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>SecondServlet</servlet-name>
<url-pattern>/1.do</url-pattern>
</servlet-mapping>
第二个servlet
ru.bmstu.SecondServlet
第二个servlet
/1.do
好的，我发现OrderPage和CatalogPage中有一个表单操作标记，它保存着servlet的URL字符串formURL=
“/OrderPage”；
//通过encodeURL传递引用自己站点的URL。
formURL=response.encodeURL（formURL）；…“\n”…
这不能包括斜杠，所以当我删除斜杠时，我有来自服务器的响应，所以“/OrderPage”必须更改为“OrderPage”。我在查看其他Servlet工作示例时发现了这一点。我认为要使此代码按设计方式工作，我必须删除/以所有形式删除动作标记。多亏viartemev的回答，我正在使用apache的3.0版本7@user3396201您需要这样的web.xml：。您使用的url是什么？当我将此代码粘贴到web.xml中时，我就知道了ve：元素类型“web app”后面必须跟属性规范“>”或“/>”。该web.xml实际做什么？？？@user3396201/web-INF/web.xml文件是应用程序的web应用程序部署描述符。该文件是一个xml文档，定义了服务器需要了解的有关应用程序的所有信息（上下文路径除外，该路径在部署应用程序时由应用程序部署人员和管理员分配）：servlet和其他组件，如筛选器或侦听器、初始化参数、容器管理的安全约束、资源、欢迎页面等。