Re: Passing external URL for DTD reference

<!DOCTYPE EXAMPLE_DTD SYSTEM "xxx.dtd"> is there in the source xml. And
xxx.dtd is at http://myserver.com/xsl/xxx.dtd (the file name in the url can
be different - it can be named as yyy.dtd!). Can I know how to make the
transformer look at this url?

I was passing in this URL to the StreamSource constructor - like
new StreamSource(new StringReader(stylesheetStream),this.dtdURL)

This sets the URL for the stylesheet. You don't want to do this,
looking up relative hrefs to imported style sheets will be botched.

Can we achieve this in any other way? I was trying to use EntityResolver

This would be correct. You have to create a parser explicitely use
it in a SAX source to take effect.

 public class MyResolver implements EntityResolver {
   public InputSource resolveEntity (String publicId, String systemId)
   {
     if (systemId.equals("xxx.dtd")) {
              // return a special input source
       MyReader reader = new MyReader();
       return new InputSource(http://myserver.com/xsl/xxx.dtd);
     } else {
              // use the default behaviour
       return null;
     }
   }
 }

Here we don't know that the file name would be "xxx.dtd". Can we say return
new InputSource(http://myserver.com/xsl/xxx.dtd); no matter what the xxx.dtd
in the xml source is?

Yes. However, the entity resolver will be invoked for every entity, and
some processors will it also invoke for the main input source. Therefore,
the default should be
  return new InputSource(systemId);
instead of returning null.