Hackademy - BigQueryServerFactory

BigQueryServerFactory.java

package ar.com.zupcat.lib.bean.audit;

import com.google.api.client.extensions.appengine.http.UrlFetchTransport;
import com.google.api.client.googleapis.auth.oauth2.GoogleCredential;
import com.google.api.client.googleapis.extensions.appengine.auth.oauth2.AppIdentityCredential;
import com.google.api.client.http.HttpRequestInitializer;
import com.google.api.client.json.jackson.JacksonFactory;
import com.google.api.services.bigquery.Bigquery;
import com.google.api.services.bigquery.BigqueryScopes;
import com.google.appengine.api.appidentity.AppIdentityServiceFactory;

import java.util.Arrays;

public final class BigQueryServerFactory {

    private static final Object LOCK_OBJECT = new Object();
    private static BigQueryServerFactory _instace = null;

    private final BigQueryClient bigQueryClientFactory;


    private BigQueryServerFactory() {
        final HttpRequestInitializer httpRequestInitializer;

        if (System.getProperty("OAUTH_ACCESS_TOKEN") != null) {
            // Good for testing and localhost environments, where no AppIdentity is available.
            httpRequestInitializer = new GoogleCredential().setAccessToken(System.getenv("OAUTH_ACCESS_TOKEN"));
        } else {
            httpRequestInitializer = new AppIdentityCredential(Arrays.asList(BigqueryScopes.BIGQUERY, BigqueryScopes.BIGQUERY_INSERTDATA));
        }

        final String appName = AppIdentityServiceFactory.getAppIdentityService().getServiceAccountName().split("@")[0];

        final Bigquery bq = new Bigquery.Builder(new UrlFetchTransport(), new JacksonFactory(), httpRequestInitializer).setApplicationName(appName).build();

        bigQueryClientFactory = new BigQueryClient(appName, bq);
    }

    public static BigQueryServerFactory instance() {
        if (_instace == null) {
            synchronized (LOCK_OBJECT) {
                if (_instace == null) {
                    _instace = new BigQueryServerFactory();
                }
            }
        }
        return _instace;
    }

    public BigQueryClient getBigQueryClientFactory() {
        return bigQueryClientFactory;
    }
}