␡
- Monitoring Creation and Destruction of the Servlet Context
- Example: Initializing Commonly Used Data
- Detecting Changes in Servlet Context Attributes
- Example: Monitoring Changes to Commonly Used Data
- Packaging Listeners with Tag Libraries
- Example: Packaging the Company Name Listeners
- Recognizing Session Creation and Destruction
- Example: A Listener That Counts Sessions
- Watching for Changes in Session Attributes
- Example: Monitoring Yacht Orders
- Using Multiple Cooperating Listeners
- The Complete Events Deployment Descriptor
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This chapter is from the book
This chapter is from the book
This chapter is from the book
This chapter is from the book
10.12 The Complete Events Deployment Descriptor
The previous sections showed various excerpts of the web.xml file for the application events examples. This section shows the file in its entirety.
Listing 10.39 web.xml (Complete version for events examples)
<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE web-app PUBLIC
"-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
"http://java.sun.com/dtd/web-app_2_3.dtd">
<web-app>
<!-- Order matters in web.xml! For the elements
used in this example, this order is required:
context-param
listener
servlet
servlet-mapping
session-config
welcome-file-list
taglib
security-constraint
login-config
-->
<!-- Since the company name changes so frequently,
supply it as a servlet context parameter instead
of embedding it into lots of different servlets and
JSP pages. The InitialCompanyNameListener will
read this value and store it in the servlet context. -->
<context-param>
<param-name>companyName</param-name>
<param-value>not-dot-com.com</param-value>
</context-param>
<!-- Also store the previous company name. -->
<context-param>
<param-name>formerCompanyName</param-name>
<param-value>hot-dot-com.com</param-value>
</context-param>
<!-- Declare the names of the session attributes that
are used to store items that customers are
purchasing. The daily special listener will
track changes to the values of these attributes. -->
<context-param>
<param-name>order-attribute-names</param-name>
<param-value>
orderedItem
purchasedItem
</param-value>
</context-param>
<!-- The item names of the current daily specials. -->
<context-param>
<param-name>daily-special-item-names</param-name>
<param-value>
chalet
car
</param-value>
</context-param>
<!-- Register the listener that sets up the
initial company name. -->
<!-- Listener declaration moved to tag library...
<listener>
<listener-class>
moreservlets.listeners.InitialCompanyNameListener
</listener-class>
</listener>
-->
<!-- Register the listener that monitors changes to
the company name.
-->
<!-- Listener declaration moved to tag library...
<listener>
<listener-class>
moreservlets.listeners.ChangedCompanyNameListener
</listener-class>
</listener>
-->
<!-- Register the session counting event listener. -->
<listener>
<listener-class>
moreservlets.listeners.SessionCounter
</listener-class>
</listener>
<!-- Register the yacht-watching event listener. -->
<listener>
<listener-class>
moreservlets.listeners.YachtWatcher
</listener-class>
</listener>
<!-- Register the listener that sets up the entries
that will be used to monitor orders for the daily
special. -->
<listener>
<listener-class>
moreservlets.listeners.DailySpecialRegistrar
</listener-class>
</listener>
<!-- Register the listener that counts orders for the daily
special. -->
<listener>
<listener-class>
moreservlets.listeners.DailySpecialWatcher
</listener-class>
</listener>
<!-- Register the listener that resets the order counts
when the names of the daily specials change. -->
<listener>
<listener-class>
moreservlets.listeners.ChangedDailySpecialListener
</listener-class>
</listener>
<!-- Assign the name ChangeCompanyName to
moreservlets.ChangeCompanyName. -->
<servlet>
<servlet-name>ChangeCompanyName</servlet-name>
<servlet-class>moreservlets.ChangeCompanyName</servlet-class>
</servlet>
<!-- Assign the name OrderHandlingServlet to
moreservlets.OrderHandlingServlet. -->
<servlet>
<servlet-name>OrderHandlingServlet</servlet-name>
<servlet-class>
moreservlets.OrderHandlingServlet
</servlet-class>
</servlet>
<!-- Assign the name ChangeDailySpecial to
moreservlets.ChangeDailySpecial. -->
<servlet>
<servlet-name>ChangeDailySpecial</servlet-name>
<servlet-class>
moreservlets.ChangeDailySpecial
</servlet-class>
</servlet>
<!-- Give a name to the servlet that redirects users
to the home page.
-->
<servlet>
<servlet-name>Redirector</servlet-name>
<servlet-class>moreservlets.RedirectorServlet</servlet-class>
</servlet>
<!-- Assign the URL /admin/ChangeCompanyName to the
servlet that is named ChangeCompanyName.
-->
<servlet-mapping>
<servlet-name>ChangeCompanyName</servlet-name>
<url-pattern>/admin/ChangeCompanyName</url-pattern>
</servlet-mapping>
<!-- Assign the URL /HandleOrders to the
servlet that is named OrderHandlingServlet.
-->
<servlet-mapping>
<servlet-name>OrderHandlingServlet</servlet-name>
<url-pattern>/HandleOrders</url-pattern>
</servlet-mapping>
<!-- Assign the URL /admin/ChangeDailySpecial to the
servlet that is named ChangeDailySpecial.
-->
<servlet-mapping>
<servlet-name>ChangeDailySpecial</servlet-name>
<url-pattern>/admin/ChangeDailySpecial</url-pattern>
</servlet-mapping>
<!-- Turn off invoker. Send requests to index.jsp. -->
<servlet-mapping>
<servlet-name>Redirector</servlet-name>
<url-pattern>/servlet/*</url-pattern>
</servlet-mapping>
<!-- Set the default session timeout to two minutes. -->
<session-config>
<session-timeout>2</session-timeout>
</session-config>
<!-- If URL gives a directory but no filename, try index.jsp
first and index.html second. If neither is found,
the result is server specific (e.g., a directory
listing). Order of elements in web.xml matters.
welcome-file-list needs to come after servlet but
before error-page.
-->
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
<welcome-file>index.html</welcome-file>
</welcome-file-list>
<!-- Register the company-name tag library. -->
<taglib>
<taglib-uri>
/company-name-taglib.tld
</taglib-uri>
<taglib-location>
/WEB-INF/company-name-taglib.tld
</taglib-location>
</taglib>
<!-- Protect everything within the "admin" directory.
Direct client access to this directory requires
authentication.
-->
<security-constraint>
<web-resource-collection>
<web-resource-name>Admin</web-resource-name>
<url-pattern>/admin/*</url-pattern>
</web-resource-collection>
<auth-constraint>
<role-name>ceo</role-name>
</auth-constraint>
</security-constraint>
<!-- Tell the server to use form-based authentication. -->
<login-config>
<auth-method>FORM</auth-method>
<form-login-config>
<form-login-page>/admin/login.jsp</form-login-page>
<form-error-page>/admin/login-error.jsp</form-error-page>
</form-login-config>
</login-config>
</web-app>
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