Spring MVC - How to return simple String as JSON in Rest Controller

Either return text/plain (as in Return only string message from Spring MVC 3 Controller) OR wrap your String is some object

public class StringResponse {

    private String response;

    public StringResponse(String s) { 
       this.response = s;
    }

    // get/set omitted...
}

Set your response type to MediaType.APPLICATION_JSON_VALUE (= "application/json")

@RequestMapping(value = "/getString", method = RequestMethod.GET,
                produces = MediaType.APPLICATION_JSON_VALUE)

and you'll have a JSON that looks like

{  "response" : "your string value" }