Getting IOException on GAE while establishing java.net connection - google-app-engine

Question

I created application that runs on GAE and connects to specific page, automatically logins to this page and AFTER login I want to receive html and process it.
here is the problematic (writer.write part and connection.connect()) part of code:
this.username = URLEncoder.encode(username, "UTF-8");
this.password = URLEncoder.encode(password, "UTF-8");
this.login = "login";
connection = (HttpURLConnection) url.openConnection();
connection.setDoOutput(true);
connection.setRequestMethod("POST");
OutputStreamWriter writer = new OutputStreamWriter(
connection.getOutputStream());
writer.write("str_login=" + login + "&str_user=" + username
+ "&str_pass=" + password);
writer.close();
connection.connect();
I am getting IOException (connection.connect()) while establishig connection. Problem is "application/x-www-form-urlencoded" data. When I pass wrong parameters to page (for example str_pasSSs, str_usernaAAme, or no parameters at all) I am not possible to login but I do get response with html of login page. So, it seems that Google App Engine does not support this kind of communication. Is it possible to login to this page in some other way that GAE supports?
In Wireshark, I saw that username and password are sent in plaintext as line-based text data (application/x-www-form-urlencoded). I know this is not safe, but it's the way it is.

Answer 1

The connection is already established implicitly when you call getOutputStream(). There is no need to call connection.connect() again.
Also, instead of closing the output writer, try flush() instead.
As a best practice, you should be closing in, out and conn in a finally block:
InputStream in = null;
OutputStream out = null;
HttpUrlConnection conn = null;
try {
...
} catch (IOException ioe) {
...
} finally {
if (in!=null) {try {in.close()} catch (IOException e) {}}
if (out!=null) {try {out.close()} catch (IOException e) {}}
if (conn!=null) {try {conn.close()} catch (IOException e) {}}
}