It is often helpful to have diagnostic information about the pages in our web application for analyzing and resolving issues. Aside from the usual error reporting mechanism of our web container, the JSF framework lacks a reliable means of obtaining detailed and precise error information about the pages in our JSF application.
Fortunately, the Facelets framework provides comprehensive diagnostic information to simplify debugging our JSF pages. For example, Facelets can provide detailed information about invalid EL expressions in our views. First, we must set the facelets.DEVELOPMENT
initialization parameter to true in web.xml
to enable detailed error reporting.
The following Facelets page example contains an unbalanced EL expression. When the page is rendered, a Facelets error page will be displayed indicating the view ID, line, and column number on which an unbalanced EL expression was declared.
error01.jsf
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional...