How to inherit RequestMappings in a Spring 3 MVC REST API

Question

I'm trying to build a RESTful API using Spring MVC. I'm shooting for clean and manageable code where the package structure follows the url structure.

So here is what I've got:

// com.test.api.library
@RequestMapping("/library/{libraryId}")
public Library getLibrary(@PathVariable long libraryId) {
   return service.getLibraryById(libraryId);
}

// com.test.api.library.book
@RequestMapping("/library/{libraryId}/book/{bookId}")
public Book getBook(@PathVariable long libraryId, @PathVariable long bookId) {
   Library library service.getLibraryById(libraryId);
   return library.getBookById(bookId);
}

While this works, I find it messy and error-prone to have to repeat "/library/{libraryId}" in all inherited @RequestMappings, /library is likely to be to root of a big part of the API and it should be written once and reused instead of written everywhere.

I would like to rewrite the book-class to something like this:

// com.test.api.library.book
@RequestMapping("/book/{bookId}")
public Book getBook(@PathVariable long bookId) {
   // long libraryId magically given to me from the library-class's getLibrary()

   Library library service.getLibraryById(libraryId);
   return library.getBookById(bookId);
}

Is there any way Spring can help me here? It is acceptable for me to use normal java inheritance, spring annotation or anything else that helps me to not write "/library/{libraryId}" as a part of every url I ever write.

Answer 1

I believe this question has been asked & answered before: Spring MVC @RequestMapping Inheritance

That said, here is one way to reduce the amount of duplicate information. I don't actually do this in my own code because I think having the URI right next to the code is more maintainable, even if it means a little duplication.

@RequestMapping(URI_LIBRARY)
public interface LibraryNamespace {
  public static String URI_LIBRARY = "/library/{libraryId}";
}

@RequestMapping(URI_BOOK)
public interface BookNamespace {
  public static String URI_BOOK = LibraryNamespace.URI_LIBRARY + "/book/{bookId}";
}

@Controller
public class LibraryController implements LibraryNamespace {
  @RequestMapping("")
  public Library get(@PathVariable long libraryId) {
    return service.getLibraryById(libraryId);
  }
}

@Controller
public class BookController implements BookNamespace {
  @RequestMapping("")
  public Book get(@PathVariable long libraryId, @PathVariable long bookId) {
    Library library service.getLibraryById(libraryId);
    return library.getBookById(bookId);
  }
}

Since I wouldn't take this approach myself, I haven't actually tried this solution! Based on my understanding of Spring, I think it should work though...