You need to use the Google ClientLogin HTTP API to request an auth token, using your C2DM account email and password:
public static String getClientLoginAuthToken() {
HttpClient client = new DefaultHttpClient();
HttpPost post = new HttpPost("https://www.google.com/accounts/ClientLogin");
try {
List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(1);
nameValuePairs.add(new BasicNameValuePair("Email", "C2DMEMAILADDRESS));
nameValuePairs.add(new BasicNameValuePair("Passwd", "C2DMPASSWORD));
nameValuePairs.add(new BasicNameValuePair("accountType", "GOOGLE"));
nameValuePairs.add(new BasicNameValuePair("source", "Google-cURL-Example"));
nameValuePairs.add(new BasicNameValuePair("service", "ac2dm"));
post.setEntity(new UrlEncodedFormEntity(nameValuePairs));
HttpResponse response = client.execute(post);
BufferedReader rd = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));
String line = "";
while ((line = rd.readLine()) != null) {
Trace.e("HttpResponse", line);
if (line.startsWith("Auth=")) {
return line.substring(5);
}
}
} catch (IOException e) {
e.printStackTrace();
}
Trace.e(TAG, "Failed to get C2DM auth code");
return "";
}
For more information on the auth token, see this tutorial:
http://www.vogella.de/articles/AndroidCloudToDeviceMessaging/article.html