com.google.cloud.bigquery.samples.GettingStarted.java Source code

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Here is the source code for com.google.cloud.bigquery.samples.GettingStarted.java

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/*
 * 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.
 */

package com.google.cloud.bigquery.samples;

// [START all]
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 com.google.api.services.bigquery.model.GetQueryResultsResponse;
import com.google.api.services.bigquery.model.QueryRequest;
import com.google.api.services.bigquery.model.QueryResponse;
import com.google.api.services.bigquery.model.TableCell;
import com.google.api.services.bigquery.model.TableRow;

import java.io.IOException;
import java.util.List;
import java.util.Scanner;

/**
 * Example of authorizing with Bigquery and reading from a public dataset.
 *
 * Specifically, this queries the shakespeare dataset to fetch the 10 of Shakespeare's works with
 * the greatest number of distinct words.
 */
public class GettingStarted {
    // [START build_service]
    /**
     * Creates an authorized Bigquery client service using Application Default Credentials.
     *
     * @return an authorized Bigquery client
     * @throws IOException if there's an error getting the default credentials.
     */
    public 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()) {
            credential = credential.createScoped(BigqueryScopes.all());
        }

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

    // [START run_query]
    /**
     * Executes the given query synchronously.
     *
     * @param querySql the query to execute.
     * @param bigquery the Bigquery service object.
     * @param projectId the id of the project under which to run the query.
     * @return a list of the results of the query.
     * @throws IOException if there's an error communicating with the API.
     */
    private static List<TableRow> executeQuery(String querySql, Bigquery bigquery, String projectId)
            throws IOException {
        QueryResponse query = bigquery.jobs().query(projectId, new QueryRequest().setQuery(querySql)).execute();

        // Execute it
        GetQueryResultsResponse queryResult = bigquery.jobs()
                .getQueryResults(query.getJobReference().getProjectId(), query.getJobReference().getJobId())
                .execute();

        return queryResult.getRows();
    }
    // [END run_query]

    // [START print_results]
    /**
     * Prints the results to standard out.
     *
     * @param rows the rows to print.
     */
    private static void printResults(List<TableRow> rows) {
        System.out.print("\nQuery Results:\n------------\n");
        for (TableRow row : rows) {
            for (TableCell field : row.getF()) {
                System.out.printf("%-50s", field.getV());
            }
            System.out.println();
        }
    }
    // [END print_results]

    /**
     * Exercises the methods defined in this class.
     *
     * In particular, it creates an authorized Bigquery service object using Application Default
     * Credentials, then executes a query against the public Shakespeare dataset and prints out the
     * results.
     *
     * @param args the first argument, if it exists, should be the id of the project to run the test
     *     under. If no arguments are given, it will prompt for it.
     * @throws IOException if there's an error communicating with the API.
     */
    public static void main(String[] args) throws IOException {
        Scanner sc;
        if (args.length == 0) {
            // Prompt the user to enter the id of the project to run the queries under
            System.out.print("Enter the project ID: ");
            sc = new Scanner(System.in);
        } else {
            sc = new Scanner(args[0]);
        }
        String projectId = sc.nextLine();

        // Create a new Bigquery client authorized via Application Default Credentials.
        Bigquery bigquery = createAuthorizedClient();

        List<TableRow> rows = executeQuery("SELECT TOP(corpus, 10) as title, COUNT(*) as unique_words "
                + "FROM [publicdata:samples.shakespeare]", bigquery, projectId);

        printResults(rows);
    }
}
// [END all]