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A.15 Integrating Servlets and JSP

543

Request Forwarding Syntax

String url = "/path/presentation1.jsp";

RequestDispatcher dispatcher =

getServletContext().getRequestDispatcher(url);

dispatcher.forward();

Forwarding to Regular HTML Pages

  If initial servlet handles 

GET

 requests only, no change is necessary.

  If initial servlet handles 

POST

, then change destination page from 

SomePage.html to SomePage.jsp so that it, too, can handle 

POST

.

Setting Up Globally Shared Beans

  Initial servlet: 

Type1 value1 = computeValueFromRequest(request);

getServletContext().setAttribute("key1", value1);

  Final JSP document: 

Setting Up Session Beans

  Initial servlet: 

Type1 value1 = computeValueFromRequest(request);

HttpSession session = request.getSession(true);

session.putValue("key1", value1);

  Final JSP document: 

Interpreting Relative URLs in the Destination 

Page

  URL of original servlet is used for forwarded requests. Browser does 

not know real URL, so it will resolve relative URLs with respect to 

original servlet's URL.

Getting a RequestDispatcher by Alternative 

Means (2.2 Only)

  By name: use 

getNamedDispatcher

 method of 

ServletContext

.

  By path relative to initial servlet's location: use the 

getRequestDispatcher

 method of 

HttpServletRequest

 rather than 

the one from 

ServletContext

. 

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

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