Java™ Application Development on Linux - Dator

Chapter 19JSP:Servlets Turned Inside OutIn our last chapter, the BudgetPro servlet example spent a lot of code generatingthe HTML output for the servlet to send back to the browser. If you want tochange the HTML for any page (for example, add a background color), youwould have to modify the Java code (obviously)—but you’re not really wantingto modify the logic of the servlet, you only want to tweak its output. TheHTML that a servlet generates can be scattered among output statements, stringconcatenations, classes, and method calls. Servlets, we might say, bury theHTML deep inside the code. We’re now going to take a look at JavaServerPages (JSP) which do the opposite—they expose the HTML and hide the codedown inside.This technique has been given the fancy description, document-centricserver-side programs. They are “document-centric” because the HTML code isso visible—JSP content looks like (and is) HTML with some additions. Theyare “server-side” because all the work is done on the server and all the additionsand special features of JSP are boiled down to a simple stream of HTML bythe time it gets to the browser.423