More Servlets and JavaServer Pages™

9.3. Accessing the Servlet Context from Filters

The ReportFilter of the previous section prints a report on the standard output whenever the designated servlet or JSP page is invoked. A report on the standard output is fine during development—when you run a server on your desktop you typically have a window that displays the standard output. During deployment, however, you are unlikely to have access to this window. So, a natural enhancement is to write the reports into the servlet log file instead of to the standard output.

The servlet API provides two log methods: one that takes a simple String and another that takes a String and a Throwable. These two methods are available from either the GenericServlet or ServletContext classes. Check your ...