We will allow third-party clients to retrieve the search results via a REST API. These results will be available either in JSON or XML.

We want to handle requests of the /api/search/mixed;keywords=springFramework form. This is really similar to the search form we already made, except that the request path begins with api. Every URI found in this namespace should return binary results.

Let's create a new SearchApiController class in the search.api package:

package masterSpringMvc.search.api;

import masterSpringMvc.search.SearchService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.social.twitter.api.Tweet;
import org.springframework.web.bind.annotation.*;

import java.util.List;

@RestController
@RequestMapping("/api/search")
public class SearchApiController {
    private SearchService searchService;

    @Autowired
    public SearchApiController(SearchService searchService) {
        this.searchService = searchService;
    }

    @RequestMapping(value = "/{searchType}", method = RequestMethod.GET)
    public List<Tweet> search(@PathVariable String searchType, @MatrixVariable List<String> keywords) {
        return searchService.search(searchType, keywords);
    }
}

This is quite similar to our previous controller, with three subtle differences:

The RestController is a shortcut to declare controllers that will return each response as if it were annotated with the @ResponseBody annotation. It tells Spring to serialize the return type to the appropriate format, which is JSON by default.

When working with a REST API, a good practice is to always specify the method you will respond to. It's rather unlikely that a request can be handled the same way for a GET or a POST method.

If you go to http://localhost:8080/api/search/mixed;keywords=springFramework, you should get a really large result, as follows:

Indeed, Spring handled the serialization of the whole Tweet class' attributes automatically, using Jackson.