This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
RWS is fundamentally a book about design, so most of it can be applied to any programming language. My model was "Design Patterns". The examples in that book are all in C++, but it's not a C++ book.
The chapters with the most Ruby code are 3 and 7, which go in-depth to design and build a complex web service client and web service, respectively. The design comes before the implementation, so even if you want to skip all the Ruby the beginnings of those chapters are worthwhile.
As for Java-specific coverage: chapter 2 has a discussion of writing web service clients in Java, and chapter 12 covers the Restlet framework. It includes part of a Restlet implementation of the Ruby service from chapter 7 (the rest is in the sample zipfile).
I should also mention that the Restlet developers went through the book and ported most of the Ruby code to Java (also in the sample zipfile). So even in chapter 3, you might be able to follow the implementation section without reading the Ruby.
It's certainly not a book about web services in Java, but we tried to make it accessible to Java programmers.