Petstore源码追踪记(3)－商业逻辑处理(五

Web tier
当使用者输入http://localhost:8080/petstore/customer.do，MainServlet接收到
Request，转到doProcess()函数：

private void doProcess(HttpServletRequest request, HttpServletResponse response)
                   throws IOException, ServletException {
    // set the locale of the user to default if not set
    if (request.getSession().getAttribute(WebKeys.LOCALE) == null) {
       request.getSession().setAttribute(WebKeys.LOCALE, defaultLocale);
    }
    try {
       getRequestProcessor().processRequest(request);
//进行转导动作(forward)               
getScreenFlowManager().forwardToNextScreen(request,response);
    } catch (Throwable ex) {
       String className = ex.getClass().getName();
       String nextScreen = getScreenFlowManager().getExceptionScreen(ex);
       // put the exception in the request
       request.setAttribute("javax.servlet.jsp.jspException", ex);
       if (nextScreen == null) {
          // send to general error screen
          ex.printStackTrace();
          throw new ServletException("MainServlet: unknown exception: " + 
className);
       }
          context.getRequestDispatcher(nextScreen).forward(request, response);
    }

}

public void forwardToNextScreen(HttpServletRequest request, HttpServletResponse 
response) throws java.io.IOException, FlowHandlerException,
javax.servlet.ServletException {
      // set the presious screen
      String fullURL = request.getRequestURI();
      // get the screen name
      String selectedURL = defaultScreen;
      int lastPathSeparator = fullURL.lastIndexOf("/") + 1;
      if (lastPathSeparator != -1) {
          selectedURL = fullURL.substring(lastPathSeparator, fullURL.length());
      }
      //请加入侦察码，以本例来说，selectedURL=customer.do
      System.out.println("selectURL="+ selectedURL);
      String currentScreen = "";
      URLMapping urlMapping = getURLMapping(selectedURL);
      if (urlMapping != null) {
            if (!urlMapping.useFlowHandler()) {
                currentScreen = urlMapping.getScreen();
　　　　　　　　//请加入侦察码，以本例来说，currentScreen =customer.screen
                System.out.println("currentScreen="+currentScreen);
            } else {
                // load the flow handler
                FlowHandler handler = null;
                String flowHandlerString = urlMapping.getFlowHandler();
                try {
                    handler = (FlowHandler)getClass().getClassLoader()
                       .loadClass(flowHandlerString).newInstance();
                    // invoke the processFlow(HttpServletRequest)
                    handler.doStart(request);
                    String flowResult = handler.processFlow(request);
                    handler.doEnd(request);
                    currentScreen = urlMapping.getResultScreen(flowResult);
                    // if there were no screens by the id then assume that the 
result was
                    //the screen itself
                    if (currentScreen == null) currentScreen = flowResult;
               } catch (Exception ex) {
                   System.err.println("ScreenFlowManager caught loading 
handler: " + ex);
               }
            }
        }
        if (currentScreen == null) {
            System.err.println("ScreenFlowManager: Screen not found for " + 
selectedURL);
            throw new RuntimeException("Screen not found for " + selectedURL);
        }
        //进行转导动作(forward)
        System.out.println("forward to "+ currentScreen);
        context.getRequestDispatcher("/" + currentScreen).forward(request, 
response);

}

<screen name="customer">
  <parameter key="title" value="Customer" direct="true"/>
  <parameter key="banner" value="/banner.jsp" />
  <parameter key="sidebar" value="/sidebar.jsp" />
  <parameter key="body" value="/customer.jsp" />
  <parameter key="mylist" value="/mylist.jsp" />
  <parameter key="footer" value="/footer.jsp" />
</screen>

<table cellpadding="5" cellspacing="0" width="100%" border="0">
<tr>
<td colspan="3"><p class="petstore_title">Contact Information</p></td>
</tr>
<tr>
<td class="petstore_form" align="right"><b>First Name</b></td> 

<td class="petstore_form" align="left"
colspan="2"><c:out value="${customer.account.contactInfo.givenName}"/></td>
</tr>

public void attributeReplaced(HttpSessionBindingEvent se) {
   processEvent(se);
}

private void processEvent(HttpSessionBindingEvent se) {
   HttpSession session = se.getSession();
   String name = se.getName();

   /* check if the value matches the signon attribute
   * if a macth fire off an event to the ejb tier that the user
   * has signed on and load the account for the user
   */
   //判别新增或覆盖属性为”SIGNED_ON_USER”则进行处理，否则略过
   if (name.equals(SignOnFilter.SIGNED_ON_USER)) {
      boolean aSignOn  = ((Boolean)se.getValue()).booleanValue();
      if (aSignOn) {
          String userName = 
(String)session.getAttribute(SignOnFilter.USER_NAME);
//请加入侦察码
System.out.println("SignOnNotifier() userName="+userName);
          // look up the model manager and webclient controller
          PetstoreComponentManager sl = 
(PetstoreComponentManager)session.getAttribute(PetstoreKeys.COMPONENT_MANAGER);
          WebController wc =  sl.getWebController(session);
          SignOnEvent soe = new SignOnEvent(userName);
          // set the EJBAction on the Event
          EventMapping em = getEventMapping(session.getServletContext(), soe);
          if (em != null) {
             soe.setEJBActionClassName(em.getEJBActionClassName());
System.out.println("EJBActionClassName="+
   em.getEJBActionClassName());
          }

          try {
             //更新资料时会用到，以本例来说只需读取，所以没有作用
             wc.handleEvent(soe, session);
          } catch (EventException e) {
             System.err.println("SignOnNotifier Error handling event " + e);
          }
          //取得Customer EJB Local Interface Reference
          CustomerLocal customer =  sl.getCustomer(session);
          // ensure the customer object is put in the session
          //将Customer EJB Local Interface存入Session
          if (session.getAttribute(PetstoreKeys.CUSTOMER) == null) {
             session.setAttribute(PetstoreKeys.CUSTOMER, customer);
          }
          // set the language to the preferred language and other preferences
          ProfileLocal profile = sl.getCustomer(session).getProfile();
          Locale locale = 
I18nUtil.getLocaleFromString(profile.getPreferredLanguage());
          session.setAttribute(PetstoreKeys.LOCALE, locale);
      }
   }
}

D:\petstore1.3.1\src\apps\petstore\src\com\sun\j2ee\blueprints\petstore\controller\web\ 
PetstoreComponentManager.java，约110列：

public CustomerLocal  getCustomer(HttpSession session) {
   ShoppingControllerLocal scEjb = getShoppingController(session);
   try {
　　　//取得ShoppingClientFacade reference
      ShoppingClientFacadeLocal scf = scEjb.getShoppingClientFacade();
      //scf.setUserId(userId);
      //取得CustomerLocal reference
      return scf.getCustomer();
   } catch (FinderException e) {
      System.err.println("PetstoreComponentManager finder error: " + e);
   } catch (Exception e) {
      System.err.println("PetstoreComponentManager error: " + e);
   }
　　return null;
}

ShoppingClientFacadeLocalEJB为Session Bean，源码在
D:\petstore1.3.1\src\apps\petstore\src\com\sun\j2ee\blueprints\petstore\controller\ejb\ 
ShoppingClientFacadeLocalEJB.java，约101列：

/*
 * Asume that the customer userId has been set
 */
public CustomerLocal getCustomer() throws FinderException {
   //请加入侦察码
   System.out.println("ShoppingClientFacadeLocalEJB.getCustomer()");
   if (userId == null) {
      throw new GeneralFailureException("ShoppingClientFacade: failed to look 
up name of customer: userId is not set" );
   }
   try {
       ServiceLocator sl = new ServiceLocator();
       CustomerLocalHome home =(CustomerLocalHome)
           sl.getLocalHome(JNDINames.CUSTOMER_EJBHOME);
       customer = home.findByPrimaryKey(userId);
    } catch (ServiceLocatorException slx) {
       throw new GeneralFailureException("ShoppingClientFacade: failed to look 
up name of customer: caught " + slx);
    }
    return customer;
}