TokenResponseException: 401 Unauthorized Exception when trying to access Admin SDK Google API.
<p>I am trying to do an extract of users in my domain by accessing the Google Admin SDK API. I am however given a 401 unauthorized exception. The code below is my settings class that contains my method to call the API. </p>

<pre><code> package com.brookfieldres.operations;

   import java.io.File;
   import java.io.IOException;
   import java.security.GeneralSecurityException;
   import java.util.ArrayList;
   import java.util.ResourceBundle;

   import org.apache.log4j.Logger;

   import com.brookfieldres.common.Constants;
   import com.google.api.client.googleapis.auth.oauth2.GoogleCredential;
   import com.google.api.client.googleapis.auth.oauth2.GoogleCredential.Builder;
   import com.google.api.services.admin.directory.Directory;
   import com.google.api.services.admin.directory.DirectoryScopes;

    public class GCAuthentication {

        private static final Logger _Log =      Logger.getLogger(GCAuthentication.class.getName()); 

    static ResourceBundle resources =  ResourceBundle.getBundle("Resources"); 

//  public static String serviceAcc = resources.getString("SERVICE_ACC_EMAIL"); 
//  public static String privKeyPath = resources.getString("PRIVATE_KEY_PATH"); 
//  public static String userEmail = resources.getString("ADMIN_ACC"); 



    public static Directory getDirectoryService(String serviceAcc, String privKeyPath, String userEmail) throws IOException, GeneralSecurityException, NullPointerException {

    //  final ArrayList&lt;String&gt; dirScopes = new ArrayList&lt;String&gt;(); 
    //      dirScopes.add(DirectoryScopes.ADMIN_DIRECTORY_USER); 


        Constants.dirScopes = new ArrayList&lt;String&gt;(); 
        Constants.dirScopes.add(DirectoryScopes.ADMIN_DIRECTORY_USER); 
        Constants.dirScopes.add(DirectoryScopes.ADMIN_DIRECTORY_CUSTOMER); 
        Constants.dirScopes.add(DirectoryScopes.ADMIN_DIRECTORY_ORGUNIT);

        GoogleCredential gCreds = new GoogleCredential.Builder()
        .setJsonFactory(Constants.JSON_FACTORY)
        .setTransport(Constants.HTTP_TRANSPORT)
        .setServiceAccountId(serviceAcc)
        .setServiceAccountUser(userEmail)
        .setServiceAccountPrivateKeyFromP12File(new File(privKeyPath))
        .setServiceAccountScopes(Constants.dirScopes)
        .build(); 

        Directory directory = new Directory.Builder(Constants.HTTP_TRANSPORT, Constants.JSON_FACTORY, gCreds).setApplicationName(Constants.APPLICATION_NAME).build(); 

        return directory; 

    }


}
</code></pre>

<p>The code below is my test case that i am using to pull users from my domain: </p>

<pre><code>package com.brookfieldres.library.test;

import org.junit.Before;
import org.junit.Test;

import static org.junit.Assert.assertFalse;

import java.io.IOException;
import java.security.GeneralSecurityException;
import org.junit.After;

import com.brookfieldres.operations.GCAuthentication;
import com.google.api.client.repackaged.com.google.common.base.Strings;
import com.google.api.services.admin.directory.Directory;
import com.google.api.services.admin.directory.model.Customer;
import com.google.api.services.admin.directory.model.User;

public class ExtractionTest { 

@Before 
    public void setUp(){}

@Test
    public void getEmails() throws IOException, NullPointerException, GeneralSecurityException{ 

        try {

            Directory directory = GCAuthentication.getDirectoryService("XXXXXXX", "XXXXXXXX", "XXXXXXX"); 
            System.out.println("The connection to Google is established"); 
            User user1 = directory.users().get("XXXXXXXX@XXXX.ca").execute(); 
            System.out.println("User is pulled."); 

    //      assertFalse(user1 == null); 

    //      if(user1 != null){ 
    //          System.out.println("Name= " + user1.getName());
    //      }

        }catch(NullPointerException e) { 
            e.printStackTrace();
        }catch (IOException e){ 
            e.printStackTrace();
        }catch (GeneralSecurityException e) { 
            e.printStackTrace();
        }


    }

@After
    public void tearDown(){ }

}
</code></pre>

<p>and Finally here is the exception that i am faced with. </p>

<pre><code>The connection to Google is established
com.google.api.client.auth.oauth2.TokenResponseException: 401 Unauthorized
    at com.google.api.client.auth.oauth2.TokenResponseException.from(TokenResponseException.java:105)
    at com.google.api.client.auth.oauth2.TokenRequest.executeUnparsed(TokenRequest.java:287)
    at com.google.api.client.auth.oauth2.TokenRequest.execute(TokenRequest.java:307)
    at com.google.api.client.googleapis.auth.oauth2.GoogleCredential.executeRefreshToken(GoogleCredential.java:384)
    at com.google.api.client.auth.oauth2.Credential.refreshToken(Credential.java:489)
    at com.google.api.client.auth.oauth2.Credential.intercept(Credential.java:217)
    at com.google.api.client.http.HttpRequest.execute(HttpRequest.java:868)
    at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.executeUnparsed(AbstractGoogleClientRequest.java:419)
    at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.executeUnparsed(AbstractGoogleClientRequest.java:352)
    at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.execute(AbstractGoogleClientRequest.java:469)
    at com.brookfieldres.library.test.ExtractionTest.getEmails(ExtractionTest.java:36)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
    at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
</code></pre>

<p>Any help would be gladly appreciated!!! </p>