Tài liệu XML by Example- P9 docx

Figure 12.1: Creating the Data Source in ODBC Before you can use the XML server, you need to create the database schema and insert a few products in the database. This is what XMLServerConsole is for. Point your browser to localhost:81/console . First click Create Tables, (see Figure 12.2). Enter the product information, as shown in Figure 12.3. 385 Building XCommerce Figure 12.2: Creating the database schema 14 2429 CH12 2.29.2000 2:25 PM Page 385 Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. Figure 12.3: Creating products in the database The Middle Tier As explained in Chapter 11, “N-Tiered Architecture and XML,” the middle tier server is a servlet that manages various XML documents. There is a document for the list of merchants or another for the list of products, and more. The servlet applies style sheets to them. The middle tier server is made of the Shop class, shown in Listing 12.5. Shop decodes the URL and routes the requests to the appropriate object. Listing 12.5: Shop.java package com.psol.xcommerce; import java.io.*; import java.util.*; import org.w3c.dom.*; import javax.servlet.*; import javax.servlet.http.*; /** * Shop manages the shop, using XSL for any output. * * @version Sep 10, 1999 386 Chapter 12: Putting It All Together: An e-Commerce Example 14 2429 CH12 2.29.2000 2:25 PM Page 386 Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. * @author Benoît Marchal <bmarchal@pineapplesoft.com> */ public class Shop extends HttpServlet { /** * the merchant list and the shopping cart */ protected MerchantCollection merchants; protected Comlet checkout; /** * return the list of merchants */ public MerchantCollection getMerchants() { return merchants; } /** * initializes the servlet */ public void init() throws ServletException { merchants = new MerchantCollection(this); checkout = new Checkout(this); } /** * handle GET request * @param request the request received from the client * @param response interface to the client * @exception IOException error writing the reply * @exception ServletException error in processing the request */ 387 The Middle Tier continues 14 2429 CH12 2.29.2000 2:25 PM Page 387 Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. protected void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException { Comlet comlet = translateURL(request); if(null != comlet) comlet.doGet(request,response); else response.sendError(HttpServletResponse.SC_NOT_FOUND); } /** * handle POST request * @param request the request received from the client * @param response interface to the client * @exception IOException error writing the reply * @exception ServletException error in processing the request */ protected void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException { Comlet comlet = translateURL(request); if(null != comlet) comlet.doPost(request,response); else response.sendError(HttpServletResponse.SC_NOT_FOUND); } /** * Returns the time it was last modified. * @param request the request received from the client * @return time in milliseconds since January 1, 1970 midnight */ protected long getLastModified(HttpServletRequest request) { try 388 Chapter 12: Putting It All Together: An e-Commerce Example Listing 12.5: continued 14 2429 CH12 2.29.2000 2:25 PM Page 388 Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. { Comlet comlet = translateURL(request); if(null != comlet) return comlet.getLastModified(); else return -1; } catch(ServletException e) { return -1; } } /** * decode the URL and select the Comlet that will * handle the request * @param request the request received from the client * @return the Comlet identified in the request * @exception problem loading one of the object */ protected Comlet translateURL(HttpServletRequest request) throws ServletException { String merchantID = null, pathInfo = request.getPathInfo(); StringTokenizer tokenizer = null; if(null != pathInfo) { tokenizer = new StringTokenizer(pathInfo,”/”); if(tokenizer.hasMoreTokens()) merchantID = tokenizer.nextToken(); } if(null == merchantID) return merchants; if(merchantID.equals(“checkout”)) return checkout; Merchant merchant = merchants.getMerchant(merchantID); 389 The Middle Tier continues 14 2429 CH12 2.29.2000 2:25 PM Page 389 Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. String productID = null; if(tokenizer.hasMoreTokens()) productID = tokenizer.nextToken(); if(null == merchant || null == productID) return merchant; else return merchant.getProduct(productID); } } The objects that really handle the request are derived from Comlet , defined in Listing 12.6. Comlet defines methods for the GET and POST requests. Listing 12.6: Comlet.java package com.psol.xcommerce; import java.io.*; import java.util.*; import javax.servlet.*; import javax.servlet.http.*; /** * Comlet is a subset of the servlet interface, Shop * delegates HTTP requests to Comlet descendants. * * @version Sep 10, 1999 * @author Benoît Marchal <bmarchal@pineapplesoft.com> */ public class Comlet implements ServletConfig { /** * properties */ protected ServletConfig servletConfig; protected long lastModified = -1; protected Shop shop; 390 Chapter 12: Putting It All Together: An e-Commerce Example Listing 12.5: continued 14 2429 CH12 2.29.2000 2:25 PM Page 390 Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. /** * creates a new Comlet * @param shop the shop it is part of */ public Comlet(Shop shop) { this.shop = shop; } /** * return the servlet config */ public ServletConfig getServletConfig() { return shop.getServletConfig(); } /** * return the shop it is part of */ public Shop getShop() { return shop; } /** * convenience: implements ServletConfig * @param name the parameter whose value is requested * @return the parameter value */ public String getInitParameter(String name) { return shop.getInitParameter(name); } /** 391 The Middle Tier continues 14 2429 CH12 2.29.2000 2:25 PM Page 391 Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. * convenience: implements ServletConfig * @return an enumeration of names */ public Enumeration getInitParameterNames() { return shop.getInitParameterNames(); } /** * convenience: implements ServletConfig * @return the config object */ public ServletContext getServletContext() { return shop.getServletContext(); } /** * handle GET request * @param request the request received from the client * @param response interface to the client * @exception IOException error writing the reply * @exception ServletException error in processing the request */ public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException { response.sendError(HttpServletResponse.SC_BAD_REQUEST); } /** * handle POST request * @param request the request received from the client * @param response interface to the client * @exception IOException error writing the reply * @exception ServletException error in processing the request 392 Chapter 12: Putting It All Together: An e-Commerce Example Listing 12.6: continued 14 2429 CH12 2.29.2000 2:25 PM Page 392 Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. */ public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException { response.sendError(HttpServletResponse.SC_BAD_REQUEST); } /** * return the time the data was last modified */ public long getLastModified() { return lastModified; } /** * data has changed, update lastModified */ public void freshened() { lastModified = System.currentTimeMillis(); } } MerchantCollection URLs in the form /shop are handled by MerchantCollection , which man- ages a list of merchants in XML. See Listing 12.7. Listing 12.8 is the list of merchants and Listing 12.9 is the style sheet. Listing 12.7: MerchantCollection.java package com.psol.xcommerce; import java.io.*; import java.util.*; import org.w3c.dom.*; import javax.servlet.*; import javax.servlet.http.*; 393 The Middle Tier EXAMPLE continues 14 2429 CH12 2.29.2000 2:25 PM Page 393 Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. /** * represents a list of merchants * * @version Sep 10, 1999 * @author Benoît Marchal <bmarchal@pineapplesoft.com> */ public class MerchantCollection extends Comlet { /** * properties */ protected Dictionary merchants = new Hashtable(); protected Document merchantsDocument = null, merchantsXSL = null; /** * creates a new Merchant object * @param shop the shop it is part of * @param ServletException error reading the merchant list */ public MerchantCollection(Shop shop) throws ServletException { super(shop); String fname = getInitParameter(“merchants.xml”); if(null != fname) merchantsDocument = XMLUtil.parse(fname); if(null == merchantsDocument) throw new UnavailableException(shop,”merchants.xml”); freshened(); Element topLevel = merchantsDocument.getDocumentElement(); Enumeration enumeration = XMLUtil.extract(topLevel,”merchant”); while(enumeration.hasMoreElements()) { 394 Chapter 12: Putting It All Together: An e-Commerce Example Listing 12.7: continued 14 2429 CH12 2.29.2000 2:25 PM Page 394 Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. [...]... HttpServletResponse response) throws IOException, ServletException { XMLUtil.transform(getDocument(), getXSL(), response.getWriter(), response.getCharacterEncoding()); } } Listing 12.8: Merchants .xml < ?xml version=”1.0”?> XMLi Your specialist for XML products! Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark 14 2429 CH12 2.29.2000 2:25 PM Page 397 The Middle Tier 397 Listing 12.9: Merchants.xsl < ?xml version=”1.0”... XMLUtil is the only class that needs updating XMLUtil is defined in Listing 12.14 Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark 14 2429 CH12 418 2.29.2000 2:25 PM Page 418 Chapter 12: Putting It All Together: An e-Commerce Example Listing 12.14: XMLUtil.java package com.psol.xcommerce; import java.io.*; import java.util.*; import org .xml. sax.*; import org.w3c.dom.*; import... productsElement.getAttribute(“href”); String update = productsElement.getAttribute(“update”); if(!XMLUtil.isEmpty(fname)) { productsDocument = XMLUtil.parse(fname); freshened(); productXSL = null; productsXSL = null; Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark 14 2429 CH12 2.29.2000 2:25 PM Page 401 The Middle Tier 401 } if(!XMLUtil.isEmpty(update)) { long u = Long.parseLong(update) * 1000; expire . id=”xmli”> <name>XMLi</name> <description>Your specialist for XML products!</description> <products href=”./data/xmli .xml />. ServletException { XMLUtil.transform(getDocument(), getXSL(), response.getWriter(), response.getCharacterEncoding()); } } Listing 12.8: Merchants .xml < ?xml version=”1.0”?>