How can I specify the username and password for making Basic-Auth requests with App Engine's URLFetch service (in Java)?
It seems I can set HTTP headers:
URL url = new URL("http://www.example.com/comment");
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestProperty("X-MyApp-Version", "2.7.3");
What are the appropriate headers for Basic-Auth?
This is a basic auth header over http:
Authorization: Basic base64 encoded(username:password)
eg:
GET /private/index.html HTTP/1.0
Host: myhost.com
Authorization: Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ==
You will need to do this:
URL url = new URL("http://www.example.com/comment");
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestProperty("Authorization",
"Basic "+codec.encodeBase64String(("username:password").getBytes());
And to do that you will want to get a base64 codec api, like the Apache Commons Codec
For those interested in doing this in Python (as I was), the code looks like this:
result = urlfetch.fetch("http://www.example.com/comment",
headers={"Authorization":
"Basic %s" % base64.b64encode("username:pass")})
You set up an Authenticator before you call openConnection() like this,
Authenticator.setDefault(new Authenticator() {
protected PasswordAuthentication getPasswordAuthentication() {
return new PasswordAuthentication(username, password.toCharArray());
}
});
Since there is only one global default authenticator, this doesn't really work well when you have multiple users doing the URLFetch in multiple threads. I would use Apache HttpClient if that's the case.
EDIT: I was wrong. App Engine doesn't allow Authenticator. Even if it's allowed, we would have the multi-thread issue with a global authenticator instance. Even though you can't create threads, your requests may still get served in different threads. So we just add the header manually using this function,
import com.google.appengine.repackaged.com.google.common.util.Base64;
/**
* Preemptively set the Authorization header to use Basic Auth.
* @param connection The HTTP connection
* @param username Username
* @param password Password
*/
public static void setBasicAuth(HttpURLConnection connection,
String username, String password) {
StringBuilder buf = new StringBuilder(username);
buf.append(':');
buf.append(password);
byte[] bytes = null;
try {
bytes = buf.toString().getBytes("ISO-8859-1");
} catch (java.io.UnsupportedEncodingException uee) {
assert false;
}
String header = "Basic " + Base64.encode(bytes);
connection.setRequestProperty("Authorization", header);
}
Using HttpURLConnection gave me some problems (for some reason the server I was trying to connect to didn't accept auth credentials), and finally I realized that it's actually much easier to do using GAE's low-level URLFetch API (com.google.appengine.api.urlfetch) like so:
URL fetchurl = new URL(url);
String nameAndPassword = credentials.get("name")+":"+credentials.get("password");
String authorizationString = "Basic " + Base64.encode(nameAndPassword.getBytes());
HTTPRequest request = new HTTPRequest(fetchurl);
request.addHeader(new HTTPHeader("Authorization", authorizationString));
HTTPResponse response = URLFetchServiceFactory.getURLFetchService().fetch(request);
System.out.println(new String(response.getContent()));
This worked.
There is a wrapper on Apache HttpClient for App Engine
please go through the post http://esxx.blogspot.com/2009/06/using-apaches-httpclient-on-google-app.html
http://peterkenji.blogspot.com/2009/08/using-apache-httpclient-4-with-google.html
