.

Alternative Means of Getting a 

RequestDispatcher

In servers that support version 2.2 of the servlet specification, there are

two additional ways of obtaining a 

RequestDispatcher

 besides the 

get 

RequestDispatcher

 method of 

ServletContext

. 

First, since most servers let you give explicit names to servlets or JSP

pages, it makes sense to access them by name rather than by path. Use the

getNamedDispatcher

 method of 

ServletContext

 for this task.

Second, you might want to access a resource by a path relative to the cur 

rent servlet's location, rather than relative to the server root. This approach is

not common when servlets are accessed in the standard manner

(

http://host/servlet/ServletName

), because JSP files would not be

accessible by means of 

http://host/servlet/...

 since that URL is

reserved especially for servlets. However, it is common to register servlets

under another path, and in such a case you can use the 

getRequest 

Dispatcher

 method of 

HttpServletRequest

 rather than the one from

ServletContext

. For example, if the originating servlet is at

http://host/travel/TopLevel

,

getServletContext().getRequestDispatcher("/travel/cruises.jsp")

could be replaced by

request.getRequestDispatcher("cruises.jsp");

15.2 Example:  An On Line Travel 

Agent

Consider the case of an on line travel agent that has a quick search page, as

shown in Figure 15 1 and Listing 15.2. Users need to enter their e mail

address and password to associate the request with their previously established

customer account. Each request also includes a trip origin, trip destination,

start date, and end date. However, the action that will result will vary substan 

Second edition of this book: www.coreservlets.com; Sequel: www.moreservlets.com.

Servlet and JSP training courses by book's author: courses.coreservlets.com.