In java how do you know whether you have an error stream from a Http(s)connection or if it is an InputStream? The only way I can tell to do it is go for both, check for null and catch any exceptions.
HttpConnection con = (HttpConnection)URL.openConnection();
//Write to output
InputStream in = con.GetInputStream();
//Vs
InputStream error = con.getErrorStream();
How does java determine which stream it has? Is it based solely on response code of the connetion? So if its >200 and >300 then its inputStream otherwhise its an errorStream?
Thanks.
user384706's answer doesn't handle all cases. HTTP_INTERNAL_ERROR (500) isn't the only response code that can create an error stream, there are many others: 400, 401, 402, 403, 404, 405, 406, 407, 408, 409, 410, 411, 412, 413, 414, 415, 501, 502, 503, 504, 505, etc.
ReplyDeleteNot only that, but connection.getResponseCode() may throw an exception if it initiated the connection and the HTTP response status code was an error-class status code. So checking for 500 (HTTP_INTERNAL_ERROR) immediately after connection.getResponseCode() may actually be unreachable code, depending on how you're accessing connection.
The strategy I have seen implemented is to use the error stream if an exception was thrown, otherwise use the input stream. The following code provides a basic structural starting point:
InputStream responseStream = null;
int responseCode = -1;
try
{
responseCode = connection.getResponseCode();
responseStream = connection.getInputStream();
}
catch(IOException e)
{
responseCode = connection.getResponseCode();
responseStream = connection.getErrorStream();
}
if (responseStream != null && responseCode != -1)
{
// Use the responseStream and responseCode.
}
else
{
// This can happen if e.g. a malformed HTTP response was received
// This should be treated as an error.
}
You can do it as following:
ReplyDeleteInputStream inStream = null;
int responseCode = connection.getResponseCode();
if (responseCode == HttpURLConnection.HTTP_INTERNAL_ERROR) {
inStream = connection.getErrorStream();
}
else{
inStream = connection.getInputStream();
}
The HTTP return code signifies what is the kind of stream to read back.