cURL and HttpURLConnection - Post JSON Data

Question

How to post JSON data using HttpURLConnection? I am trying this:

HttpURLConnection httpcon = (HttpURLConnection) ((new URL("a url").openConnection()));
httpcon.setDoOutput(true);
httpcon.setRequestProperty("Content-Type", "application/json");
httpcon.setRequestProperty("Accept", "application/json");
httpcon.setRequestMethod("POST");
httpcon.connect();

StringReader reader = new StringReader("{'value': 7.5}");
OutputStream os = httpcon.getOutputStream();

char[] buffer = new char[4096];
int bytes_read;    
while((bytes_read = reader.read(buffer)) != -1) {
    os.write(buffer, 0, bytes_read);// I am getting compilation error here
}
os.close();

I am getting compilation error in line 14.

The cURL request is:

curl -H "Accept: application/json" \
-H "Content-Type: application/json" \
-d "{'value': 7.5}" \
"a URL"

Is this the way to handle cURL request? Any information will be very helpful to me.

Thanks.

You should post the compilation error – ykaganovich Mar 08 '12 at 19:08 — ykaganovich, Mar 08 '12 at 19:08

score 31 · Accepted Answer · answered Mar 08 '12 at 19:08

31

OutputStream expects to work with bytes, and you're passing it characters. Try this:

HttpURLConnection httpcon = (HttpURLConnection) ((new URL("a url").openConnection()));
httpcon.setDoOutput(true);
httpcon.setRequestProperty("Content-Type", "application/json");
httpcon.setRequestProperty("Accept", "application/json");
httpcon.setRequestMethod("POST");
httpcon.connect();

byte[] outputBytes = "{'value': 7.5}".getBytes("UTF-8");
OutputStream os = httpcon.getOutputStream();
os.write(outputBytes);

os.close();

answered Mar 08 '12 at 19:08

ykaganovich

14,736
8
59
96

Is it not possible to send a complex json object in this manner? For instance ... "{"points":[{"point":{"latitude":40.8195085182092,"longitude":-73.75127574479318},"description":"test"},{"point":{"latitude":40.2195085182092,"longitude":-74.75127574479318},"description":"test2"}],"mode":"WALKING"}" ... is an object that I'm sending via this method and I get an HTTP Response Code of 500. – crowmagnumb Dec 03 '13 at 04:30
@CrowMagnumb You should post a separate question. 500 means that the server has an internal error trying to process your request. – ykaganovich Dec 03 '13 at 19:59
OK, I've done so [here](http://stackoverflow.com/questions/20452366/http-response-code-500-sending-complex-json-object-using-httpurlconnection) Thanks for the suggestion. – crowmagnumb Dec 08 '13 at 10:34

score 9 · Answer 2 · answered Mar 26 '12 at 23:15

9

You may want to use the OutputStreamWriter class.

final String toWriteOut = "{'value': 7.5}";
final OutputStreamWriter osw = new OutputStreamWriter(connection.getOutputStream());
osw.write(toWriteOut);
osw.close();

answered Mar 26 '12 at 23:15

Anthony Chuinard

1,028
10
17

what would be the benefit over `OutputStream`? – Darpan Jul 30 '15 at 07:15

cURL and HttpURLConnection - Post JSON Data

2 Answers2

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