如何始终如一地处理球衣和tomcat错误？

Question

I have implemented some (REST) service with jersey. If there is a bad request jersey handles the error and answers with some JSON content. There is an ExceptionMapper that should catch everything:

public class MyExceptionMapper implements ExceptionMapper<Throwable>

But if there is an invalid HTTP request - eg invalid content type - tomcat handles the exception before jersey has a chance to do so. The resulting response is some ugly tomcat HTML error page instead of the desired JSON.

I know that it is possible to set an <error-page> in the deployment descriptor but there I have no access to any error details.

Is there a way to prevent tomcat from catching this error? If so, jersey could catch it with its ExceptionMapper and return the correct response.

Answer 1

You know you can set an "error page", but what are you pointing it to? If it's just a static webpage, then yes, you won't have access to error details. But if you forward it to a servlet that is made for handling errors, then you should have details on your your error, and can pass control back to jersey, etc.

ie

web.xml:

  <error-page>
    <error-code>415</error-code>
    <location>/InvalidContentHandler</location>
  </error-page>
  <error-page>
    <exception-type>java.lang.Throwable</exception-type>
    <location>/InvalidContentHandler</location>
  </error-page>

NOTE: in the above web.xml, you should replace java.lang.Throwable with the actual exception type you are encountering, which you can get with the "javax.servlet.error.exception" attribute, shown below.

InvalidContentHandler.java:

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    processError(request, response);
}

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    processError(request, response);
}

private void processError(HttpServletRequest request, HttpServletResponse response) throws IOException {

    // Pass control to Jersey, or get some info:
    Throwable throwable = (Throwable) request.getAttribute("javax.servlet.error.exception");
    Integer statusCode = (Integer) request.getAttribute("javax.servlet.error.status_code");
    String servletName = (String) request.getAttribute("javax.servlet.error.servlet_name");
    String requestUri = (String) request.getAttribute("javax.servlet.error.request_uri");
    ...
}