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ECLIPSE WEB TOOLS PLATFORM developing java web applications PHẦN 5

Chúng tôi thảo luận các khía cạnh kiến trúc của bộ phận này trong Chương 5. Chúng tôi thảo luận về WTP hỗ trợ cho logic trình bày trong chương này và cho doanh nghiệp logic trong Chương, tiếp theo 8. Việc phân chia giữa trình bày và logic kinh doanh đặc biệt quan trọng trong các ứng dụng web vì hai lý do. | 274 CHAPTER 7 The Presentation Tier import javax.xml.transform.Result import javax.xml.transform.Source import javax.xml.transform.Templates import javax.xml.transform.Transformer import javax.xml.transform.TransformerException import javax.xml.transform.TransformerFactory import javax.xml.transform.stream.StreamResult import javax.xml.transform.stream.StreamSource Servlet implementation class for Servlet ScheduleServlet public class ScheduleServlet extends HttpServlet implements javax.servlet.Servlet private static final long serialVersionUID 1L protected void doGet HttpServletRequest request HttpServletResponse response throws ServletException IOException try ServletContext context getServletContext InputStream xsl context.getResourceAsStream schedule.xsl Source xslSource new StreamSource xsl TransformerFactory factory TransformerFactory.newInstance Templates templates factory.newTemplates xslSource Transformer transformer templates.newTransformer InputStream xml context.getResourceAsStream schedule.xml Source xmlSource new StreamSource xml PrintWriter out response.getWriter Result htmlResult new StreamResult out transformer.transform xmlSource htmlResult response.flushBuffer out.flush catch TransformerException e throw new ServletException e The servlet uses TrAX to apply schedule.xsl to schedule.xml. TrAX uses the AbstractFactory creational pattern as described in Chapter 3 of Design Patterns Gamma1995 by Erich Gamma et al. This pattern lets you create a transformer without specifying the concrete implementation class. There are several Java XSLT implementations such as Xalan and Saxon so using the AbstractFactory pattern lets your code be independent of the particular Iteration 6 Servers Dynamic Web Projects and Servlets 275 implementation that is configured in your JDK. Using TrAX therefore makes your code more portable. The servlet uses the servlet context to get input streams for schedule.xml and schedule.xsl. This technique is preferred to directly .