How to Properly Handle Exceptions in a JSP/Servlet App?

Question

How do you properly handle errors encountered in a servlet? Right now, the app that I inherited (uses only plain JSP/Servlet) has a superclass called Controller

Answer 1

The standard thing to do is have your Servlet's doXxx() method (eg. doGet(), doPost(), etc.) throw a ServletException and allow the container to catch and handle it. You can specify a custom error page to be shown in WEB-INF/web.xml using the tag:

    500
    /error.jsp

If you end up catching an Exception you can't elegantly handle, just wrap it in a ServletException like this:

try {
    // code that throws an Exception
} catch (Exception e) {
    throw new ServletException(e);
}