Understanding The Translation Process

JSP translators generate standard Java code for a JSP page implementation class. This class is essentially a servlet class wrapped with features for JSP functionality.

Translator generates servlet code in the page implementation class, it automatically handles some of the standard programming overhead. For both the on-demand translation model and the pre-translation model, generated code automatically includes the following features:

• JSP container that implements the standard javax.servlet.jsp.HttpJspPage interface (which extends the more generic javax.servlet.jsp.JspPage interface, which in turn extends the standard javax.servlet.Servlet interface).
• It implements the _jspService() method specified by the HttpJspPage interface. This method, often referred to generically as the "service" method, is the central method of the page implementation class. Code from any Java scriptlets and expressions in the JSP page is incorporated into this method implementation.
• It includes code to request an HTTP session, unless your JSP source code specifically sets session=false (which can be done in a page directive).

The service method, _jspService(), of the page implementation class includes print commands--out.print() calls on the implicit out object--to print any static text in the JSP page. The OracleJSP translator, however, places the static text itself in an inner class within the page implementation class. The service method out.print() statements reference attributes of the inner class to print the text.

For example, translating MyPage.jsp will always result in the string "MyPage" being part of the page implementation class name, Java source file name, and class file name. Translating MyPage.jsp results in page implementation class _MyPage in source file _MyPage.java, which is compiled into _MyPage.class.

 

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