[SOLVED] How do I customize embedded Tomcat’s error pages programmatically?

How do I customize embedded Tomcat’s error pages programmatically?

I am using programmatic configuration of an Embedded Tomcat server very similar to Heroku’s example here.

I supply my own Servlet class to Tomcat using this approach.

How can I customize the error pages that Tomcat renders?

Solution

  public void configureErrorPages(StandardContext ctx) {
    ErrorPage error404 = new ErrorPage();
    error404.setLocation("/errors/404");
    error404.setErrorCode(HttpServletResponse.SC_NOT_FOUND);
    ctx.addErrorPage(error404);

    ErrorPage error500 = new ErrorPage();
    error500.setLocation("/errors/500");
    error500.setErrorCode(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
    ctx.addErrorPage(error500);
  }

This is using org.apache.catalina.core.StandardContext, org.apache.tomcat.util.descriptor.web.ErrorPage, and jakarta.servlet.http.HttpServletResponse. With the above configuration, on a 404, Tomcat will dispatch a second request to /errors/404. Your servlet can react to it with a custom error page. Similarly with the 500 error. This was adapted from some spring-boot code.

There are no xmls to write with this approach.