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15.5 Forwarding Requests From JSP Pages

381

where. For example, a request might go to a JSP page that normally presents

results of a certain type and that forwards the request elsewhere only when it

receives unexpected values.

Sending requests to servlets instead of JSP pages requires no changes

whatsoever in the use of the 

RequestDispatcher

. However, there is special

syntactic support for forwarding requests from JSP pages. In JSP, the

jsp:forward

 action is simpler and easier to use than wrapping up 

Request 

Dispatcher

 code in a scriptlet. This action takes the following form:

The 

page

 attribute is allowed to contain JSP expressions so that the desti 

nation can be computed at request time. For example, the following sends

about half the visitors to 

http://host/examples/page1.jsp

 and the oth 

ers to 

http://host/examples/page2.jsp

.

<% String destination;

if (Math.random() > 0.5) {

destination = "/examples/page1.jsp";

} else {

destination = "/examples/page2.jsp";

}

%>

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