Gmail API's Java integration issue

Question

I'm involved in a develop that lead me to integrate Gmail API in my Java project.

Like everybody I started my test bringing the GmailQuickstart example provided in the official documentation.

I perform a few test on it but I'm not able to login and list labels of my account.

This is my class :

import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.List;

import com.google.api.client.auth.oauth2.Credential;
import com.google.api.client.googleapis.auth.oauth2.GoogleClientSecrets;
import com.google.api.client.googleapis.auth.oauth2.GoogleCredential;
import com.google.api.client.googleapis.javanet.GoogleNetHttpTransport;
import com.google.api.client.http.HttpTransport;
import com.google.api.client.json.JsonFactory;
import com.google.api.client.json.jackson2.JacksonFactory;
import com.google.api.client.util.store.FileDataStoreFactory;
import com.google.api.services.gmail.Gmail;
import com.google.api.services.gmail.GmailScopes;
import com.google.api.services.gmail.model.Label;
import com.google.api.services.gmail.model.ListLabelsResponse;

public class ComunicoTestSergio {

    private static HttpTransport HTTP_TRANSPORT;
    private static final JsonFactory JSON_FACTORY = JacksonFactory.getDefaultInstance();
    private static final java.io.File DATA_STORE_DIR = new java.io.File(System.getProperty("user.home"), ".credentials/ComunicoTestSergio.json");
    private static FileDataStoreFactory DATA_STORE_FACTORY;
    private static final String APPLICATION_NAME ="comunico";

    static {
        try {
            HTTP_TRANSPORT = GoogleNetHttpTransport.newTrustedTransport();
            DATA_STORE_FACTORY = new FileDataStoreFactory(DATA_STORE_DIR);
        } catch (Throwable t) {
            t.printStackTrace();
            System.exit(1);
        }
    }
    public static Credential authorize() throws IOException {
        InputStream is = ComunicoTestSergio.class.getResourceAsStream(
                "/comunico-test-sergio-client_secret_113926736970383780927.json");
        InputStreamReader isr = new InputStreamReader(is);
        GoogleClientSecrets clientSecrets = GoogleClientSecrets.load(JSON_FACTORY, isr);           
        Credential credential = new GoogleCredential.Builder()
                .setTransport( HTTP_TRANSPORT )
                .setJsonFactory( JSON_FACTORY )
                .setServiceAccountId( "comunico-test-sergio [email protected]" ) 
                .setServiceAccountScopes( Arrays.asList(GmailScopes.GMAIL_LABELS) )
                .setServiceAccountUser( "[email protected]" )
                .setClientSecrets( clientSecrets )
                .build();
        return credential;
    }
    public static Gmail getGmailService() throws Exception {
        Credential credential = authorize();
        return new Gmail.Builder( HTTP_TRANSPORT, JSON_FACTORY, credential )
                .setApplicationName( APPLICATION_NAME )
                .build();
    }

    public static void main(String[] args) {
        try {
            Gmail service = getGmailService();
            String user = "me";
            ListLabelsResponse listResponse =service.users().labels().list(user).execute();
            List<Label> labels = listResponse.getLabels();
            if (labels.size() == 0) { System.out.println("No labels found."); } 
            else {
                System.out.println("Labels:");
                for (Label label : labels) {
                    System.out.printf("- %s\n", label.getName());
                }
            }
        } catch ( Exception ex ) {
            ex.printStackTrace();
        }
    }
}

This is my maven pom dependencies list :

<dependency>
      <groupId>com.google.apis</groupId>
      <artifactId>google-api-services-gmail</artifactId>
      <version>v1-rev40-1.21.0</version>
    </dependency>
  </dependencies>

That generate this dependencies set :

/home/sbelli/.m2/repository/com/google/apis/google-api-services-gmail/v1-rev40-1.21.0/google-api-services-gmail-v1-rev40-1.21.0.jar
/home/sbelli/.m2/repository/com/google/api-client/google-api-client/1.21.0/google-api-client-1.21.0.jar
/home/sbelli/.m2/repository/com/google/oauth-client/google-oauth-client/1.21.0/google-oauth-client-1.21.0.jar
/home/sbelli/.m2/repository/com/google/http-client/google-http-client/1.21.0/google-http-client-1.21.0.jar
/home/sbelli/.m2/repository/org/apache/httpcomponents/httpclient/4.0.1/httpclient-4.0.1.jar
/home/sbelli/.m2/repository/org/apache/httpcomponents/httpcore/4.0.1/httpcore-4.0.1.jar
/home/sbelli/.m2/repository/commons-logging/commons-logging/1.1.1/commons-logging-1.1.1.jar
/home/sbelli/.m2/repository/commons-codec/commons-codec/1.3/commons-codec-1.3.jar
/home/sbelli/.m2/repository/com/google/code/findbugs/jsr305/1.3.9/jsr305-1.3.9.jar
/home/sbelli/.m2/repository/com/google/http-client/google-http-client-jackson2/1.21.0/google-http-client-jackson2-1.21.0.jar
/home/sbelli/.m2/repository/com/fasterxml/jackson/core/jackson-core/2.1.3/jackson-core-2.1.3.jar
/home/sbelli/.m2/repository/com/google/guava/guava-jdk5/17.0/guava-jdk5-17.0.jar

This is my JSON credential file (downloaded from Google Developer Console) :


    {
    "installed":{
     "client_id":"my_client_id_x",
     "project_id":"my_project_id",
     "auth_uri":"https://accounts.google.com/o/oauth2/auth",
     "token_uri":"https://accounts.google.com/o/oauth2/token",
     "auth_provider_x509_cert_url":"https://www.googleapis.com/oauth2/v1/certs"
     }
    }

When i run my example class i obtain this issue :

java.lang.IllegalArgumentException
    at com.google.api.client.repackaged.com.google.common.base.Preconditions.checkArgument(Preconditions.java:111)
    at com.google.api.client.util.Preconditions.checkArgument(Preconditions.java:37)
    at com.google.api.client.googleapis.auth.oauth2.GoogleCredential.<init>(GoogleCredential.java:317)
    at com.google.api.client.googleapis.auth.oauth2.GoogleCredential$Builder.build(GoogleCredential.java:515)
    at it.trew.comunico.business.test.ComunicoTestSergio.authorize(ComunicoTestSergio.java:51)
    at it.trew.comunico.business.test.ComunicoTestSergio.getGmailService(ComunicoTestSergio.java:55)
    at it.trew.comunico.business.test.ComunicoTestSergio.main(ComunicoTestSergio.java:63)

If i comment the lines :

.setServiceAccountId( "comunico-test-sergio [email protected]" )
.setServiceAccountScopes( Arrays.asList(GmailScopes.GMAIL_LABELS) )
.setServiceAccountUser( "[email protected]" )

i obtain the issue

com.google.api.client.googleapis.json.GoogleJsonResponseException: 401 Unauthorized
{
  "code" : 401,
  "errors" : [ {
    "domain" : "global",
    "location" : "Authorization",
    "locationType" : "header",
    "message" : "Login Required",
    "reason" : "required"
  } ],
  "message" : "Login Required"
}
    at com.google.api.client.googleapis.json.GoogleJsonResponseException.from(GoogleJsonResponseException.java:145)
    at com.google.api.client.googleapis.services.json.AbstractGoogleJsonClientRequest.newExceptionOnError(AbstractGoogleJsonClientRequest.java:113)
    at com.google.api.client.googleapis.services.json.AbstractGoogleJsonClientRequest.newExceptionOnError(AbstractGoogleJsonClientRequest.java:40)
    at com.google.api.client.googleapis.services.AbstractGoogleClientRequest$1.interceptResponse(AbstractGoogleClientRequest.java:321)
    at com.google.api.client.http.HttpRequest.execute(HttpRequest.java:1056)
    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 it.trew.comunico.business.test.ComunicoTestSergio.main(ComunicoTestSergio.java:65)

What's the matter?! I follow step by step the online tutorial... :(

Every help is appreciate!

your Json file looks like Oauth2 credentials. your code says service account. What did you create on the Google Developers console and what should you have created? can you add a link to the tutorial you are following the Gmail quick start I found for java doesn't contain the service account code you have there. — DaImTo
1) developers.google.com/gmail/api/quickstart/java#prerequisites 2) developers.google.com/identity/protocols/… 3) developers.google.com/gmail/api/auth/… 4) developers.google.com/gmail/api/auth/… — Sergio Belli
ant this for the correct set of libraries : developers.google.com/api-client-library/java/apis/gmail/… — Sergio Belli
JSON credential are of the OAuth 2.0 client ID, but i have also registered a service account key... — Sergio Belli

nvnagr nvnagr · Accepted Answer · 2016-03-30T21:20:02

Before you should jump into using service accounts.. here are a few questions.

Is this app going to access just your gmail account or a lot of users?
How are those users authorizing this app? 2a. If app is used by a company then an admin can authorize a set of users. 2b. If app is used by individual users then they should authorize it through Oauth approval flow.

           .setServiceAccountId( "comunico-test-sergio [email protected]" ) 
            .setServiceAccountScopes( Arrays.asList(GmailScopes.GMAIL_LABELS) )
            .setServiceAccountUser( "[email protected]" )

In your example you created a service account and are trying to access emails of [email protected]. How did [email protected] authorize the service account to grant access? It probably didn't. For 2a, a service account makes more sense. For 2b, you should be getting the user through oauth approval flow and get a code and exchange it for a refresh/access token and use it for the apis.

Gmail API's Java integration issue

1 Answers