java类库详细讲解

				
				
				
				Getting a Request Parameter in a JSP Page
				(Java Developers Almanac Example)
				
				
				
				
				
				
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				The Java Developers Almanac 1.4
				
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				    javax.servlet.jsp
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				        Java Server Pages Input
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				    e1052.  
				    Getting a Request Parameter in a JSP Page
				
				In a GET request, the request parameters are taken from the query
				string (the data following the question mark on the URL).  For
				example, the URL http://hostname.com?p1=v1&p2=v2 contains two
				request parameters - p1 and p2.  In a POST request, the
				request parameters are taken from both query string and the posted
				data which is encoded in the body of the request.
				
				 This example demonstrates how to include the value of a request
				parameter in the generated output:
				
				
				
				    Hello <b><%= request.getParameter("name") %></b>!
				
				If the page was accessed with the URL:
				
				
				    http://hostname.com/mywebapp/mypage.jsp?name=John+Smith
				
				the resulting output would be:
				
				
				    Hello <b>John Smith</b>!
				
				If name is not specified on the query string, the output would be:
				
				
				    Hello <b>null</b>!
				
				This example uses the value of a query parameter in a scriptlet:
				
				
				    <%
				        if (request.getParameter("name") == null) {
				            out.println("Please enter your name.");
				        } else {
				            out.println("Hello <b>"+request.getParameter(i)+"</b>!");
				        }
				    %>
				
				See also e1065 Getting a Request Parameter Using JSTL in a JSP Page.
				
				
				
				
				             Related Examples
				        
				
				
				
				
				e1053. 
				    Including a File in a JSP Page
				
				
				
				e1054. 
				    Passing Parameters to Another JSP Page
				
				
				
				e1055. 
				    Using a Bean in a JSP Page
				
				
				
				
				
				
				
				
				        See also: 
				
				    Java Server Pages
				  
				
				
				    Java Server Pages Headers
				  
				
				
				    Java Server Pages Output
				  
				
				
				
				
				
				
				
				
				
				© 2002 Addison-Wesley.