Hackademy - BigQueryClientFactory

BigQueryClientFactory.java

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

import ar.com.zupcat.lib.bean.enums.ErrorType;
import ar.com.zupcat.lib.exception.GAEException;
import com.google.api.client.auth.oauth2.Credential;
import com.google.api.client.auth.oauth2.TokenResponse;
import com.google.api.client.googleapis.auth.oauth2.*;
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.jackson.JacksonFactory;
import com.google.api.services.bigquery.Bigquery;
import com.google.api.services.bigquery.BigqueryScopes;

import java.io.*;
import java.util.Collections;
import java.util.Properties;

public final class BigQueryClientFactory {

    private static final String REDIRECT_URI = "urn:ietf:wg:oauth:2.0:oob";
    private static final String PREVIOUSLY_AUTHORIZED_TOKENS_FILE = "google-cloud-previously-authorized-tokens.properties";

    // Objects for handling HTTP transport and JSON formatting of API calls
    private final HttpTransport HTTP_TRANSPORT = new NetHttpTransport();
    private final JsonFactory JSON_FACTORY = new JacksonFactory();

    private final GoogleClientSecrets googleClientSecrets;
    private final String appName;

    private final BigQueryClient bigQueryClientFactory;


    /**
     * @param projectNumberId   Google Cloud ProjectNumber. It could be seen in, for instance, https://console.developers.google.com/project/apps~topgoalsprod
     * @param appName           just a reference name. For instance topgoalsprod
     * @param clientSecretsJson obtained by creating a OAuth ClientId on, for instance, https://console.developers.google.com/project/apps~topgoalsprod/apiui/credential - Then you should add the downloaded json file content. See main method in this class for an example
     */
    public BigQueryClientFactory(final String projectNumberId, final String appName, final String clientSecretsJson) {
        try {
            this.appName = appName;
            googleClientSecrets = GoogleClientSecrets.load(JSON_FACTORY, new StringReader(clientSecretsJson));
            final Bigquery bigquery;

            final String previouslyAuthorizedTokens = tryLoadPreviouslyAuthorizedTokens();

            if (previouslyAuthorizedTokens != null) {
                final GoogleCredential credential = new GoogleCredential.Builder()
                        .setTransport(HTTP_TRANSPORT)
                        .setJsonFactory(JSON_FACTORY)
                        .setClientSecrets(googleClientSecrets)
                        .build()
                        .setFromTokenResponse(new TokenResponse().setRefreshToken(previouslyAuthorizedTokens));

                credential.refreshToken();

                bigquery = buildService(credential);

            } else {
                final String authorizeUrl = new GoogleAuthorizationCodeRequestUrl(
                        googleClientSecrets,
                        REDIRECT_URI,
                        Collections.singleton(BigqueryScopes.BIGQUERY)).setState("").build();

                System.err.println("Paste this URL into a web browser to authorize BigQuery Access:\n" + authorizeUrl);

                System.err.println("... and type the code you received here: ");

                final BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
                final String authorizationCode = in.readLine();

                // Exchange the auth code for an access token and refesh token
                final Credential credential = exchangeCode(authorizationCode);

                // Store the refresh token for future use.
                savePreviouslyAuthorizedTokens(credential.getRefreshToken());

                bigquery = buildService(credential);
            }

            bigQueryClientFactory = new BigQueryClient(projectNumberId, bigquery);

        } catch (final Exception _exception) {
            throw new GAEException(ErrorType.PROGRAMMING, _exception);
        }
    }

    public BigQueryClient getBigQueryClientFactory() {
        return bigQueryClientFactory;
    }

    private Bigquery buildService(final Credential credential) {
        return new Bigquery.Builder(HTTP_TRANSPORT, JSON_FACTORY, credential).setApplicationName(appName).build();
    }

    private Credential exchangeCode(final String authorizationCode) throws IOException {
        final GoogleAuthorizationCodeFlow flow = new GoogleAuthorizationCodeFlow.Builder(HTTP_TRANSPORT,
                JSON_FACTORY,
                googleClientSecrets,
                Collections.singleton(BigqueryScopes.BIGQUERY))
                .setAccessType("offline").setApprovalPrompt("force").build();

        final GoogleTokenResponse response = flow.newTokenRequest(authorizationCode).setRedirectUri(REDIRECT_URI).execute();

        return flow.createAndStoreCredential(response, null);
    }

    private String tryLoadPreviouslyAuthorizedTokens() {
        String result = null;

        try {
            final Properties properties = new Properties();
            properties.load(new FileInputStream(PREVIOUSLY_AUTHORIZED_TOKENS_FILE));
            result = (String) properties.get("freshToken");

        } catch (final Exception _exception) {
            // ok to ignore
        }
        return result;
    }

    private void savePreviouslyAuthorizedTokens(final String freshToken) {
        try {
            final Properties properties = new Properties();
            properties.setProperty("freshToken", freshToken);
            properties.store(new FileOutputStream(PREVIOUSLY_AUTHORIZED_TOKENS_FILE), null);
        } catch (final Exception _exception) {
            // ok to ignore
        }
    }
}