GCS_Auth.java Source code

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Here is the source code for GCS_Auth.java

Source

/* Copyright (c) 2012 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */

import org.apache.commons.codec.binary.Base64;
import java.security.KeyStore;
import java.security.PrivateKey;
import java.security.Signature;
import java.io.*;
import java.net.*;

/**
This script acquires an oauth2 bearer access_token use with authenticated GCS 
ShoppingAPI and ContentAPI requests.  GCS customers should use one of the 
libraries shown below to get the token in a production setting.  This script 
is provided to  demonstrate the encryption and structure of getting an oauth2 
bearer tokens. Ensure the computer this script is run on is synced with a 
NTP server.
    
REFERENCE :
https://developers.google.com/commerce-search/docs/shopping_auth
https://developers.google.com/accounts/docs/OAuth2ServiceAccount
http://code.google.com/p/google-api-java-client/wiki/OAuth2
       
   javac -cp .:commons-codec-1.6.jar GCS_Auth.java
       
   java -cp .:commons-codec-1.6.jar GCS_Auth --client_id= --key= 
       
 client_id=<clientID Service account  'email'>    
 key = <private key for the service account>
     
  This code is not supported by Google
*/

public class GCS_Auth {

    private String access_token = null;

    public static void main(String[] args) {
        String client_id = null;
        String key = null;

        for (String a : args) {
            if (a.startsWith("--key="))
                key = a.split("=")[1];
            if (a.startsWith("--client_id="))
                client_id = a.split("=")[1];
        }

        if ((args.length < 2) || client_id == null || key == null) {
            System.out.println("specify --key= --client_id=");
            System.exit(-1);
        }

        GCS_Auth j = new GCS_Auth(client_id, key);
    }

    public GCS_Auth(String client_id, String key) {
        String SCOPE = "https://www.googleapis.com/auth/shoppingapi";
        SCOPE = SCOPE + " " + "https://www.googleapis.com/auth/structuredcontent";
        try {
            String jwt_header = "{\"alg\":\"RS256\",\"typ\":\"JWT\"}";

            long now = System.currentTimeMillis() / 1000L;
            long exp = now + 3600;
            String iss = client_id;
            String claim = "{\"iss\":\"" + iss + "\",\"scope\":\"" + SCOPE
                    + "\",\"aud\":\"https://accounts.google.com/o/oauth2/token\",\"exp\":" + exp + ",\"iat\":" + now
                    + "}";

            String jwt = Base64.encodeBase64URLSafeString(jwt_header.getBytes()) + "."
                    + Base64.encodeBase64URLSafeString(claim.getBytes("UTF-8"));

            byte[] jwt_data = jwt.getBytes("UTF8");

            Signature sig = Signature.getInstance("SHA256WithRSA");

            KeyStore ks = java.security.KeyStore.getInstance("PKCS12");
            ks.load(new FileInputStream(key), "notasecret".toCharArray());

            sig.initSign((PrivateKey) ks.getKey("privatekey", "notasecret".toCharArray()));
            sig.update(jwt_data);
            byte[] signatureBytes = sig.sign();
            String b64sig = Base64.encodeBase64URLSafeString(signatureBytes);

            String assertion = jwt + "." + b64sig;

            //System.out.println("Assertion: " + assertion);

            String data = "grant_type=assertion";
            data += "&" + "assertion_type" + "="
                    + URLEncoder.encode("http://oauth.net/grant_type/jwt/1.0/bearer", "UTF-8");
            data += "&" + "assertion=" + URLEncoder.encode(assertion, "UTF-8");

            URLConnection conn = null;
            try {
                URL url = new URL("https://accounts.google.com/o/oauth2/token");
                conn = url.openConnection();
                conn.setDoOutput(true);
                OutputStreamWriter wr = new OutputStreamWriter(conn.getOutputStream());
                wr.write(data);
                wr.flush();

                BufferedReader rd = new BufferedReader(new InputStreamReader(conn.getInputStream()));
                String line;
                while ((line = rd.readLine()) != null) {
                    if (line.split(":").length > 0)
                        if (line.split(":")[0].trim().equals("\"access_token\""))
                            access_token = line.split(":")[1].trim().replace("\"", "").replace(",", "");
                    System.out.println(line);
                }
                wr.close();
                rd.close();
            } catch (Exception ex) {
                InputStream error = ((HttpURLConnection) conn).getErrorStream();
                BufferedReader br = new BufferedReader(new InputStreamReader(error));
                StringBuilder sb = new StringBuilder();
                String line;
                while ((line = br.readLine()) != null) {
                    sb.append(line);
                }
                System.out.println("Error: " + ex + "\n " + sb.toString());
            }
            //System.out.println(access_token);
        } catch (Exception ex) {
            System.out.println("Error: " + ex);
        }
    }

    private String access_token() {
        return access_token;
    }
}