Here’s a little tidbit. If you need to determine what domain a request may have been referred from, such as when doing JSONP work, here’s a code snippet that might help.

def uri = new java.net.URI(request.getHeader("referer"))
def domainName = uri.getHost()

The java.net package contains the URI class which aides in working with URIs and URLs. And in Grails the request processed by the servlet engine is an object named request. That object contains a method called getHeader that allows you to get any header value by name.

Using this little bit of code I am able to check the referring domain of a JSONP request against a MongoDB collection that contains a list of valid domains for a given registered user. Then if the request came from a valid domain I serve up the requested JSON response.

Hope that’s helpful to someone. Happy coding!