Java - HttpUrlConnection

Question

Hi I've started using HttpUrlConnection and I have a question regarding on when the Http Request is actually sent.

I read somewhere that the actual request is sent when getInputStream() is called. However, I've written some test code to play around with this for a POST request:

In this version I'm calling on getResponseCode() before getInputStream()

URL obj = new URL(myUrl);
HttpURLConnection httpclient = (HttpURLConnection) obj.openConnection();
httpclient.setRequestMethod("POST");
**int responseCode = httpclient.getResponseCode();** 
    try { 
        inStream = httpclient.getInputStream(); 
    }
    catch (IOException ie) { 
        inStream = httpclient.getErrorStream(); 
    }
System.out.println("response code = " + responseCode);

I receive a response code of 200. So this got me thinking that the request is not being sent at getInputStream(), but at an earlier method. Does anyone have any insight on this?

Thanks!

Subhrajyoti Majumder · Accepted Answer · 2014-06-19 07:51:51Z

1

Code Insight for HttpURLConnection#getResponseCode() - openJDK 7

public int getResponseCode() throws IOException {
454        /*
455         * We're got the response code already
456         */
457        if (responseCode != -1) {
458            return responseCode;
459        }
460
461        /*
462         * Ensure that we have connected to the server. Record
463         * exception as we need to re-throw it if there isn't
464         * a status line.
465         */
466        Exception exc = null;
467        try {
468            getInputStream();
469        } catch (Exception e) {
470            exc = e;
471        }
472        ...

Basically response code will -1 at initialization which means we have not got any response code. So It will establish a connection URL#getInputStream() and get the response code.

edited Jun 19, 2014 at 7:51

answered Jun 19, 2014 at 6:58

Subhrajyoti Majumder

41.3k13 gold badges84 silver badges103 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

EpicPandaForce Over a year ago

This is indeed the case, reading the source of java.net.HttpURLConnection in JDK8. Afterwards, it reads the status line from the header and obtains the code.

Subhrajyoti Majumder Over a year ago

umm... Actually it makes the connection.

user7702 Over a year ago

So at the very core, it is getInputStream() that will be making the connection/sending the request? Looks like getResponseCode() uses getInputStream to make the connection.

Bruno Grieder · Accepted Answer · 2014-06-19 06:56:34Z

0

getResponseCode() does the the same thing: it flushes the request and starts reading the response.

Actually, you MUST try to start reading the response (code or stream) for the request to be totally sent to the server.

answered Jun 19, 2014 at 6:56

Bruno Grieder

30k10 gold badges73 silver badges104 bronze badges

2 Comments

user7702 Over a year ago

So does getResponseCode() and getInputStream() both flush the request? in my code I commented out getResponseCode(), so I never call on getResponseCode. Yet, I'm still getting a proper response...so is getResponseCode required for the request to be completely sent?

Bruno Grieder Over a year ago

Either one or the other

Collectives™ on Stack Overflow

Java - HttpUrlConnection

2 Answers 2

3 Comments

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

3 Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related