How do I could add additional header on Response B

问题:

Just see the code snippet of SpringMVC-3.2.x controller action method. Its quite easy to generate JSON but unable to add addtional custom header only for this action/specific action method for specific controller. not common for all JSON @ResponseBody action method .

@RequestMapping(value="ajaxDenied", method = RequestMethod.GET)
public @ResponseBody Map<String, Object> ajaxDenied(ModelMap model) {

    Map<String, Object> message = new HashMap<String, Object>();
    message.put("severity", "error");
    message.put("summary", "Restricted access only");
    message.put("code", 200);

    Map<String, Object> json = new HashMap<String, Object>();
    json.put("success", false);
    json.put("message", message);

    return json;
}

In the different way I could add additional headers as my demand but here is some problem in generating pure JSON. Its generate buggy JSON and able to parse few browser.

@RequestMapping(value="ajaxSuccess", method = RequestMethod.GET)
public ResponseEntity<String> ajaxSuccess(){
    Map<String, Object> message = new HashMap<String, Object>();

    message.put("severity", "info");
    message.put("location", "/");
    message.put("summary", "Authenticated successfully.");
    message.put("code", 200);

    Map<String, Object> json = new HashMap<String, Object>();
    json.put("success", true);
    json.put("message", message);

    String data = "";
    try {
        ObjectMapper mapper = new ObjectMapper();
        data  = mapper.writeValueAsString(json);
    } catch (Exception e) { //TODO
    }
    HttpHeaders headers = new HttpHeaders();
    headers.add("Content-Type", "application/json; charset=UTF-8");
    headers.add("X-Fsl-Location", "/");
    headers.add("X-Fsl-Response-Code", "302");
    return (new ResponseEntity<String>(data, headers, HttpStatus.OK));
}

this action method could generate JSON String with escape character rather than pure JSON so depend on browser how it will be parse, Its cause failure for chrome. The output just look like

"{\"message\":{\"summary\":\"Authenticated successfully.\",\"location\":\"/\",\"severity\":\"info\",\"code\":\"200\"},\"success\":true}"

but our desired output

{
  "message":{
    "summary": "Authenticated successfully.",
    "location":"/",
    "severity":"info",
    "code":"200"
  },
  "success":true
}

I want to generate pure JSON with additional headers based on conditions for specific action of specific controller.

回答1:

You can add headers to the ResponseEntity builder. I think it is cleaner this way.

import org.springframework.http.HttpHeaders;
import org.springframework.http.ResponseEntity;

// ...

@GetMapping("/my/endpoint")
public ResponseEntity myEndpointMethod() {

    HttpHeaders headers = new HttpHeaders();
    headers.add(HttpHeaders.CONTENT_TYPE, "application/json; charset=UTF-8");

    return ResponseEntity.ok()
            .headers(headers)
            .body(data);
}

回答2:

Here is the solution as the suggestion of M. Deinum

@RequestMapping(value="ajaxSuccess", method = RequestMethod.GET)
public ResponseEntity<Map<String, Object>> ajaxSuccess(){
    Map<String, Object> message = new HashMap<String, Object>();

    message.put("severity", "info");
    message.put("location", "/");
    message.put("summary", "Authenticated successfully.");
    message.put("code", 200);

    Map<String, Object> json = new HashMap<String, Object>();
    json.put("success", true);
    json.put("message", message);

    HttpHeaders headers = new HttpHeaders();
    headers.add("Content-Type", "application/json; charset=UTF-8");
    headers.add("X-Fsl-Location", "/");
    headers.add("X-Fsl-Response-Code", "302");
    return (new ResponseEntity<Map<String, Object>>(json, headers, HttpStatus.OK));
}

回答3:

You can also use HttpServletResponse for adding your status and headers in a more easy way:

@RequestMapping(value="ajaxSuccess", method = RequestMethod.GET)
@ResponseBody
public String ajaxSuccess(HttpServletResponse response) {
  response.addHeader("header-name", "value");
  response.setStatus(200);
  return "Body";
}

Therefore you need to add following maven dependency as provided:

<dependency>
    <groupId>org.apache.tomcat</groupId>
    <artifactId>tomcat-servlet-api</artifactId>
    <version>7.0.53</version>
    <scope>provided</scope>
</dependency>