How to get JSON object from HTTP request in Java

Question

I'm now trying to get JSON Object with using HTTP request in Java cord.

I want to know how I can get response or JSON object in the following cord.

Please let me know.

(In this program, I try to get Wikipedia categories of the article "New York". )

 String requestURL = "http://en.wikipedia.org/w/api.php?action=query&prop=categories&format=json&clshow=!hidden&cllimit=10&titles=" + words[i];
 URL wikiRequest = new URL(requestURL);
 URLConnection connection = wikiRequest.openConnection();  
 connection.setDoOutput(true);  

                    /**** I'd like to get response here. ****/

 JSONObject json = Util.parseJson(response);

Do NOT do this. You will get OOM's if the request is relatively big and it will be very hard to fix. — Edison
– Edison, Commented May 19, 2013 at 22:46

Tunaki · Accepted Answer · 2016-03-27 13:56:02Z

4

Just 2 lines of code with JSONTokener

JSONTokener tokener = new JSONTokener(wikiRequest.openStream());
JSONObject root = new JSONObject(tokener);

edited Mar 27, 2016 at 13:56

Tunaki

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answered Mar 27, 2016 at 13:55

ShaileshAher

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1 Comment

dasjanik Over a year ago

URL.openStream() returns an InputStream... JSONTokener expects an String though?

kgautron · Accepted Answer · 2012-08-10 12:48:31Z

3

Scanner scanner = new Scanner(wikiRequest.openStream());
String response = scanner.useDelimiter("\\Z").next();
JSONObject json = Util.parseJson(response);
scanner.close();

answered Aug 10, 2012 at 12:48

kgautron

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2 Comments

Mike Stoddart Over a year ago

What library contains the Util class you are using? This answer might force the developer to include a new dependency that they might not want.

kgautron Over a year ago

It was in the original question. I do not know what is behind. I reused it in my answer because if this method does what its name suggests then there is no reason to change it to something else (at least in the scope of this question).

markus · Accepted Answer · 2012-08-10 12:44:15Z

0

If you are using URLConnection you should be able to read the stream instead of getting a response object:

BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));

see: http://docs.oracle.com/javase/tutorial/networking/urls/readingWriting.html

answered Aug 10, 2012 at 12:44

markus

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Comments

Serhat · Accepted Answer · 2013-05-19 22:40:51Z

Sample implementation with corn-httpclient & corn-converter

HttpClient client = new HttpClient(new URI(http://en.wikipedia.org/w/api.php?action=query&prop=categories&format=json&clshow=!hidden&cllimit=10&titles=" + words[i]));
HttpResponse response = client.sendData(HTTP_METHOD.GET);
if (! response.hasError()) {
String jsonString = response.getData();
JsTypeComplex jsonResponse =  (JsTypeComplex) JsonStringParser.parseJsonString(jsonString);
JsTypeList resultsArr = (JsTypeList) jsonResponse.get("results");

Maven dependencies:

<dependency>
    <groupId>net.sf.corn</groupId>
    <artifactId>corn-httpclient</artifactId>
    <version>1.0.0</version>
</dependency>
<dependency>
    <groupId>net.sf.corn</groupId>
    <artifactId>corn-converter</artifactId>
    <version>1.0.0</version>
</dependency>

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