OkHttpClient client = new OkHttpClient();
client.setAuthenticator(new Authenticator() {
public Request authenticate(Proxy proxy, Response response) throws IOException {
  String credential = Credentials.basic("user", "password");
  return response.request().newBuilder()
      .header("Authorization", credential)
      .build();
}

public Request authenticateProxy(Proxy proxy, Response response) 
throws IOException {
  return null;
}
});

private final OkHttpClient client = new OkHttpClient();

public void run() throws Exception {
 client.setAuthenticator(new Authenticator() {
  @Override public Request authenticate(Proxy proxy, Response response) {
   System.out.println("Authenticating for response: " + response);
   System.out.println("Challenges: " + response.challenges());
   String credential = Credentials.basic("jesse", "password1");
   return response.request().newBuilder()
     .header("Authorization", credential)
     .build();
  }

  @Override public Request authenticateProxy(Proxy proxy, Response response) {
   return null; // Null indicates no attempt to authenticate.
  }
 });

 Request request = new Request.Builder()
   .url("http://publicobject.com/secrets/hellosecret.txt")
   .build();

 Response response = client.newCall(request).execute();
 if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);

 System.out.println(response.body().string());
}