How do I not log a particular type of Exception in Logback?

Question

How do I configure Logback to ignore logging on exceptions of a particular type?

Answer 1

This question is 5 years old, but I'm supplying the solution I found just to keep it up to date.

I found a solution in the offical docs: http://logback.qos.ch/manual/layouts.html

For my particular situation, which is a 17 year old web site running plain old servlets (ah, the days), the servlet is now throwing an exception if the user was not logged in. So here's my code snippets:

Servlet

  try {
    InvalidLoginException.throwIfBadLogin(webUser);

    // main logic here

  } catch (InvalidLoginException e) {
    throw e;
  } catch (Throwable t) {
    log.error(t);
    throw new UnhandledException(t);
  }

web.xml

    com.mycompany.servlet.exception.InvalidLoginException
    /servlet/Login

From the setup above, I didn't want to log this exception as it's not really an exception, but rather a break in logic to redirect to login.

So, the start of my logback.xml file is this:

  
    
      throwable != null && throwable instanceof com.mycompany.servlet.exception.InvalidLoginException
    

and further down in the logback.xml file, my appenders:

  
    
      %d{MM-dd HH:mm:ss.SSS} %-5level %logger{36} - %msg %ex{full,InvalidLoginExceptionSuppressor}%n
      false
    

Also note, in order to this work, I had to include janino to handle the expression parsing.