Thursday, February 1, 2007

Can I invoke a JSP error page from a servlet?

Yes, you can invoke the JSP error page and pass the exception object to it from within a servlet. The trick is to create a request dispatcher for the JSP error page, and pass the exception object as a javax.servlet.jsp.jspException request attribute. However, note that you can do this from only within controller servlets.If your servlet opens an OutputStream or PrintWriter; the JSP engine will throw the following translation error:
Java.lang.IllegalStateException: Cannot forward as OutputStream or Writer has already been obtained the following code snippet demonstrates the invocation of a JSP error page from within a controller servlet:

protected void sendErrorRedirect(HttpServletRequest request,
HttpServletResponse response, String errorPageURL, Throwable e) throws
ServletException, IOException {
request.setAttribute ("javax.servlet.jsp.jspException", e);
getServletConfig().getServletContext().
getRequestDispatcher(errorPageURL).forward(request, response);
}
public void doPost(HttpServletRequest request, HttpServletResponse
response)
{
try {
// do something
} catch (Exception ex) {
try {
sendErrorRedirect(request,response,"/jsp/MyErrorPage.jsp",ex);
} catch (Exception e) {
e.printStackTrace();
}
}
}


SOURCE : www.referjava.com

No comments: