HttpURLConnection.getResponseCode() returns -1 on second invocation

Question

I seem to be running into a peculiar problem on Android 1.5 when a library I\'m using (signpost 1.1-SNAPSHOT), makes two consecutive connections to a remote server. The sec

Answer 1

Can you verify that the connection is not getting closed before you finish reading the response? Maybe HttpClient parses the response code right away, and saves it for future queries, however HttpURLConnection could be returning -1 once the connection is closed?

Answer 2

I've encountered the same problem when I did not read in all the data from the InputStream before closing it and opening a second connection. It was also fixed either with System.setProperty("http.keepAlive", "false"); or simply just looping until I've read the rest of the InputStream.

Not completely related to your issue, but hope this helps anyone else with a similar problem.

Answer 3

Google provided an elegant workaround since it's only happening prior to Froyo:

private void disableConnectionReuseIfNecessary() {
    // HTTP connection reuse which was buggy pre-froyo
    if (Integer.parseInt(Build.VERSION.SDK) < Build.VERSION_CODES.FROYO) {
        System.setProperty("http.keepAlive", "false");
    }
}

Cf. http://android-developers.blogspot.ca/2011/09/androids-http-clients.html

Answer 4

Or, you can set HTTP header in the connection (HttpUrlConnection):

conn.setRequestProperty("Connection", "close");

Answer 5

Try set this property to see if it helps,

http.keepAlive=false

I saw similar problems when server response is not understood by UrlConnection and client/server gets out of sync.

If this solves your problem, you have to get a HTTP trace to see exactly what's special about the response.

EDIT: This change just confirms my suspicion. It doesn't solve your problem. It just hides the symptom.

If the response from first request is 200, we need a trace. I normally use Ethereal/Wireshark to get the TCP trace.

If your first response is not 200, I do see a problem in your code. With OAuth, the error response (401) actually returns data, which includes ProblemAdvice, Signature Base String etc to help you debug. You need to read everything from error stream. Otherwise, it's going to confuse next connection and that's the cause of -1. Following example shows you how to handle errors correctly,

public static String get(String url) throws IOException {

    ByteArrayOutputStream os = new ByteArrayOutputStream();
    URLConnection conn=null;
    byte[] buf = new byte[4096];

    try {
        URL a = new URL(url);
        conn = a.openConnection();
        InputStream is = conn.getInputStream();
        int ret = 0;
        while ((ret = is.read(buf)) > 0) {
            os.write(buf, 0, ret);
        }
        // close the inputstream
        is.close();
        return new String(os.toByteArray());
    } catch (IOException e) {
        try {
            int respCode = ((HttpURLConnection)conn).getResponseCode();
            InputStream es = ((HttpURLConnection)conn).getErrorStream();
            int ret = 0;
            // read the response body
            while ((ret = es.read(buf)) > 0) {
                os.write(buf, 0, ret);
            }
            // close the errorstream
            es.close();
            return "Error response " + respCode + ": " + 
               new String(os.toByteArray());
        } catch(IOException ex) {
            throw ex;
        }
    }
}