google-http-java-client json更新现有对象

Question

i'm trying to use google-http-java-client on android and parse JSON responses from my server. do do that i'm using the following code (provided by the examples of the project)

    private static final HttpTransport HTTP_TRANSPORT = AndroidHttp.newCompatibleTransport();
    private static final JsonFactory JSON_FACTORY = new JacksonFactory();
    HttpRequestFactory requestFactory = HTTP_TRANSPORT
                .createRequestFactory(new HttpRequestInitializer() {
                    @Override
                    public void initialize(HttpRequest request) {
                        request.setParser(new JsonObjectParser(JSON_FACTORY));
                    }
                });
    HttpRequest request = requestFactory.buildGetRequest(new GenericUrl(url + paramsList));
    HttpResponse response = request.execute();

and everything works fine for new objects with

result = response.parseAs(PxUser.class);

but i need to update an existing object with the data from the json string. with jackson only i can use the following code but with the google client i cannot find any solution.

InputStream in = -get-http-reponse-
ObjectMapper mapper = new ObjectMapper();
ObjectReader reader = mapper.readerForUpdating(MySingleton.getInstance());
reader.readValue(InputStream in);

so i need a way to update an existing object just like with this jackson example but by using the client.

is there a way? do i have to use jackson-databind.jar? how can i accomplish this? thanks in advance

PS: i can switch to gson if its needed, no problem

Answer 1

It depends on whatever endpoint is receiving the API call, and what it expects the request to look like.

The Google HTTP Java Client simply handles the processes like making the call, encoding and decoding an object, exponential backoff, etc for you. It's up to you to create the request that does what you want and how the server expects it to look.

Likely, the API you're making the request to expects an object update to be made with a PUT request. The updated object is likely going to be the content of the request, encoded in some specific format. Let's assume JSON, since you're parsing JSON responses. So for the purpose of example, let's say you're going to request an object, modify it, then send it back.

First, you get the resource and parse it into your object:

PxUser myUser = response.parseAs(PxUser.class);

Then you modify the object somehow

myUser.setName("Frodo Baggins");

Now you want to send it back to the server as a JSON object in a PUT request:

// httpbin.org is a wonderful URL to test API calls against as it returns whatever if received.
GenericUrl url = new GenericUrl("http://httpbin.org/put");
JsonHttpContent content = new JsonHttpContent(new JacksonFactory(), myUser);
HttpRequest request = requestFactory.buildPutRequest(url, content);
HttpResponse response = request.execute();
System.out.println(response.parseAsString());

The specifics of how you encode and update your content is totally up to you and the API's specification. This is especially easy if you're creating the server receiving the call too.

If you're working with a preexisting API, you may want to update the question with the specific problem (API "x" requires a response that looks like Blah; how do I do that in the google-http-java-client).

If you're working with a Google API, you'll want to be using the google-api-java-client which does all of this work for you.