content-length in HttpURLConnection

Question

I'm trying to send a body in x-www-form-urlencoded to my local Web API. I can make GET without any problems. Here is what I do:

    String urlParameters = "user=User&label=GPU+Temp&file=src%2FDataSource0.txt&backgroundColor=rgb(255%2C255%2C255%2C0)&borderColor=rgb(255%2C255%2C255%2C0)&pointBorderColor=rgb(255%2C255%2C255%2C0)&pointHoverBackgroundColor=rgb(255%2C255%2C255%2C0)&pointHoverBorderColor=rgb(255%2C255%2C255%2C0)&min=0&max=100&stepSize=50";

    byte[] postData = urlParameters.getBytes(Charset.forName("UTF-8"));
    int postDataLength = postData.length;
    String request = "http://192.168.1.30:6262/api/values";
    URL url = new URL(request);
    con = (HttpURLConnection) url.openConnection();
    con.setDoOutput(true);
    con.setInstanceFollowRedirects(false);
    con.setRequestMethod("POST");
    con.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
    con.setRequestProperty("charset", "utf-8");
    con.setRequestProperty("Content-Length", Integer.toString(postDataLength));
    con.connect();

java.net.ProtocolException: content-length promised 598 bytes, but received 0

So it means that I'm not sending any data in my POST, how come?

you need to send your postData like con.getOutputStream().write(postData) — Mick, Dec 01 '17 at 13:39

score 3 · Accepted Answer · answered Dec 01 '17 at 13:37

3

Using con.setRequestProperty("Content-Length", Integer.toString(postDataLength)); you're just sending the lenght of your postDataLength, you're not actually setting it's body. In order to actually send your variable to the webservice you need to do this before calling the connect():

OutputStream os = con.getOutputStream();
os.write(urlParameters.getBytes("UTF-8"));
os.close();

answered Dec 01 '17 at 13:37

LS_

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That what i thought, body sent was empty. Thank you for you time. – BeGreen Dec 01 '17 at 13:38
@BeGreen No problem! Glad I could help :) – LS_ Dec 01 '17 at 13:40

score 0 · Answer 2 · answered Aug 08 '19 at 15:47

You need do this:

            body = datos.toString();
            content_bytes = body.getBytes("UTF-8");
            content_length = content_bytes.length;



            // establecer headers.
            connection.setRequestProperty( "Content-Type", "application/json; charset=utf-8" );
            connection.setRequestProperty( "Content-Length", Integer.toString( content_length  ) );

.....

            dataOutputStream = new DataOutputStream( connection.getOutputStream() );
            dataOutputStream.write(body.getBytes("UTF-8"));

Hi, welcome to Stack Overflow! Please [edit] your answer to elaborate a bit on how this code works and how it will solve the problem. Thank you! — grooveplex, Aug 08 '19 at 16:08

content-length in HttpURLConnection

2 Answers2