将 POST 从一个 api 转发到另一个时出现错误代码 415

Question

I'm sending an application/json type from the postman client to a java API that forwards all the requests to the specific API for that case. On this concrete case, I have a login API and I want to center code heard this JSON:

JSON from the postman

{
    "name": "random name",
    "password": "random passwd"
}

The API that does the forward

@RequestMapping(produces = MediaType.APPLICATION_JSON_UTF8_VALUE)
public String redirectHttpRequest(HttpServletRequest request, @Value("${endpoint}") String newURL,
        HttpServletResponse response) throws IOException {

    try {

        RestTemplate restTemplate = new RestTemplate();
        String result = null;


        String body = IOUtils.toString(request.getReader());

        if (request.getMethod().equals("GET")) {
            // result = restTemplate.getForObject(redirectUrl.toString(), String.class);
        } else if (request.getMethod().equals("POST")) {
            result = restTemplate.postForObject(newURL, body, String.class);

        }
        return result;

    } catch (HttpClientErrorException e) {
        System.out.println(e);
        return "OLA";
    }

}

That new URL is the URL were the other API is (which, in this case, is localhost:8080 and is from the application.properties file).

I've tested the login API through postman and it works, but when I try to connect it to that forward API I got the following error:

org.springframework.web.client.HttpClientErrorException: 415 null.

I would like to know what I am doing wrong or an alternative way to do it.

Postman call

Second endpoint code

The value of the body passed to the second endpoint

The User class

public class User {

private String name;

private String password;

private List<String> groups;

public User(String name, String password) {
    this.name = name;
    this.password = password;
    this.groups = new ArrayList<String>();
}

public User() {

}

public String getName() {
    return this.name;
}

public String getPassword() {
    return this.password;
}

public List<String> getGroups() {
    return this.groups;
}

public String toString() {
    return "User: " + this.name + "\nGroups: " + this.groups;
}

Answer 1

The problem is that you are getting the 415 error code. That means that your /login endpoint is not expecting the payload type you are sending him, see here

415 (Unsupported Media Type)

The 415 error response indicates that the API is not able to process the client's supplied media type, as indicated by the Content-Type request header. For example, a client request including data formatted as application/xml will receive a 415 response if the API is only willing to process data formatted as application/json.

For example, the client uploads an image as image/svg+xml, but the server requires that images use a different format.

I think is this because when you call postForObject , you are not telling the media type of your payload. So instead of sending the json String alone, you need to wrap it into an HttpEntity that holds the body and also a header that specifies the media type of the payload you are forwarding. Try this out:

...
} else if (request.getMethod().equals("POST")) {
    HttpHeaders headers = new HttpHeaders();
    headers.setContentType(MediaType.APPLICATION_JSON_UTF8_VALUE);
    HttpEntity<String> entity = new HttpEntity<>(body, headers);
    result = restTemplate.postForObject(newURL, entity, String.class);
}
...