JavaSercer Pages application = pageContext.getServletContext( ); config = pageContext.getServletConfig( ); session = pageContext.getSession( ); out = pageContext.getOut( ); out.write(”rn rn rn rn” + ” rn

Hello World

rn” + ” It’s “); out.print( new java.util.Date( ).toString( ) ); out.write(” and all is well.rn rn” + “rn”); } catch (Exception ex) { if (out.getBufferSize( ) != 0) out.clear( ); pageContext.handlePageException(ex); } finally { out.flush( ); _ jspxFactory.releasePageContext(pageContext); } } } The generated servlet in Example 3.3 looks a lot more complex than the hand-coded version in Example 3.1. That’s because a number of objects you can use in a JSP page must always be initialized (the hand-coded version doesn’t need this generic initialization). These details are not important now; programming examples later in the book will show you how to use all objects of interest. Instead, you should note that the servlet generated from the JSP page is a regular servlet. The _jspService( ) method corresponds to the service( ) method in the hand-coded servlet; it’s called every time the page is requested. The request and response objects are passed as arguments to the method, so the JSP page has access to all the same information as does a regular servlet. This means it can read user input passed as request parameters, adjust the response based on header values (like the ones described in Chapter 2), get access to the session state, etc. - just like a regular servlet. The highlighted code section in Example 3.3 shows how the static HTML from the JSP page in Example 3.2 has been embedded in the resulting code. Also note that the Java code to retrieve the current date and time has been inserted in the servlet as-is. By letting the JSP container convert the JSP page into a servlet that combines code for adding HTML to the response with small pieces of Java code for dynamic content, you get the best of both worlds. You can use familiar web page development tools to design the static parts of the web page, drop in JSP elements that generate the dynamic parts, and still enjoy all the benefits of servlets. page 31
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