bqutils.BigQueryServiceFactory.java Source code

Introduction

Here is the source code for bqutils.BigQueryServiceFactory.java

Source

package bqutils;/*
                * Copyright (c) 2015 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.
                */

// [START imports]

import com.google.api.client.googleapis.auth.oauth2.GoogleCredential;
import com.google.api.client.http.HttpTransport;
import com.google.api.client.http.javanet.NetHttpTransport;
import com.google.api.client.json.JsonFactory;
import com.google.api.client.json.jackson2.JacksonFactory;
import com.google.api.services.bigquery.Bigquery;
import com.google.api.services.bigquery.BigqueryScopes;

import java.io.IOException;
import java.util.Collection;

//
// Copied from this GCP sample code:
//   https://github.com/GoogleCloudPlatform/java-docs-samples/blob/master/bigquery/src/main/java/com/google/cloud/bigquery/samples/BigQueryServiceFactory.java
//

/**
 * This class creates our Service to connect to BigQuery including auth.
 */
public final class BigQueryServiceFactory {

    /**
     * Private constructor to disable creation of this utility Factory class.
     */
    private BigQueryServiceFactory() {
    }

    /**
     * Singleton service used through the app.
     */
    private static Bigquery service = null;

    /**
     * Mutex created to create the singleton in thread-safe fashion.
     */
    private static Object serviceLock = new Object();

    /**
     * Threadsafe Factory that provides an authorized BigQuery service.
     * @return The BigQuery service
     * @throws IOException Throw if there is an error connecting to BigQuery.
     */
    public static Bigquery getService() throws IOException {
        if (service == null) {
            synchronized (serviceLock) {
                if (service == null) {
                    service = createAuthorizedClient();
                }
            }
        }
        return service;
    }

    /**
     * Creates an authorized client to Google BigQuery.
     *
     * @return The BigQuery Service
     * @throws IOException Thrown if there is an error connecting
     */
    // [START get_service]
    private static Bigquery createAuthorizedClient() throws IOException {
        // Create the credential
        HttpTransport transport = new NetHttpTransport();
        JsonFactory jsonFactory = new JacksonFactory();
        GoogleCredential credential = GoogleCredential.getApplicationDefault(transport, jsonFactory);

        // Depending on the environment that provides the default credentials (e.g. Compute Engine, App
        // Engine), the credentials may require us to specify the scopes we need explicitly.
        // Check for this case, and inject the BigQuery scope if required.
        if (credential.createScopedRequired()) {
            Collection<String> bigqueryScopes = BigqueryScopes.all();
            credential = credential.createScoped(bigqueryScopes);
        }

        return new Bigquery.Builder(transport, jsonFactory, credential).setApplicationName("BigQuery Samples")
                .build();
    }
    // [END get_service]

}