import com.google.auth.oauth2.ComputeEngineCredentials; //导入依赖的package包/类
/**
 * Initializes OAuth2 credential using preconfigured ServiceAccount settings on the local
 * GCE VM. See: <a href="https://developers.google.com/compute/docs/authentication"
 * >Authenticating from Google Compute Engine</a>.
 */
public static Credentials getCredentialFromMetadataServiceAccount()
    throws IOException, GeneralSecurityException {
  Credentials cred = new ComputeEngineCredentials(getHttpTransport());
  try {
    cred.refresh();
  } catch (IOException e) {
    throw new IOException("Error getting access token from metadata server at: " +
        ComputeCredential.TOKEN_SERVER_ENCODED_URL, e);
  }
  return cred;
}
 

import com.google.auth.oauth2.ComputeEngineCredentials; //导入依赖的package包/类
/** Sends a large unary rpc with compute engine credentials. */
public void computeEngineCreds(String serviceAccount, String oauthScope) throws Exception {
  ComputeEngineCredentials credentials = ComputeEngineCredentials.create();
  TestServiceGrpc.TestServiceBlockingStub stub = blockingStub
      .withCallCredentials(MoreCallCredentials.from(credentials));
  final SimpleRequest request = SimpleRequest.newBuilder()
      .setFillUsername(true)
      .setFillOauthScope(true)
      .setResponseSize(314159)
      .setResponseType(PayloadType.COMPRESSABLE)
      .setPayload(Payload.newBuilder()
          .setBody(ByteString.copyFrom(new byte[271828])))
      .build();

  final SimpleResponse response = stub.unaryCall(request);
  assertEquals(serviceAccount, response.getUsername());
  assertFalse(response.getOauthScope().isEmpty());
  assertTrue("Received oauth scope: " + response.getOauthScope(),
      oauthScope.contains(response.getOauthScope()));

  final SimpleResponse goldenResponse = SimpleResponse.newBuilder()
      .setOauthScope(response.getOauthScope())
      .setUsername(response.getUsername())
      .setPayload(Payload.newBuilder()
          .setType(PayloadType.COMPRESSABLE)
          .setBody(ByteString.copyFrom(new byte[314159])))
      .build();
  assertEquals(goldenResponse, response);
}
 

import com.google.auth.oauth2.ComputeEngineCredentials; //导入依赖的package包/类
@Bean
@ConditionalOnMissingBean
public CredentialsProvider googleCredentials() throws Exception {
	CredentialsProvider credentialsProvider;

	Credentials propertyCredentials = this.gcpProperties.getCredentials();

	List<String> scopes = resolveScopes();

	if (!StringUtils.isEmpty(propertyCredentials.getLocation())) {
		credentialsProvider = FixedCredentialsProvider
				.create(GoogleCredentials.fromStream(
						propertyCredentials.getLocation().getInputStream())
				.createScoped(scopes));
	}
	else {
		credentialsProvider = GoogleCredentialsProvider.newBuilder()
				.setScopesToApply(scopes)
				.build();
	}

	try {
		com.google.auth.Credentials credentials = credentialsProvider.getCredentials();

		if (LOGGER.isInfoEnabled()) {
			if (credentials instanceof UserCredentials) {
				LOGGER.info("Default credentials provider for user "
						+ ((UserCredentials) credentials).getClientId());
			}
			else if (credentials instanceof ServiceAccountCredentials) {
				LOGGER.info("Default credentials provider for service account "
						+ ((ServiceAccountCredentials) credentials).getClientEmail());
			}
			else if (credentials instanceof ComputeEngineCredentials) {
				LOGGER.info("Default credentials provider for Google Compute Engine.");
			}
			LOGGER.info("Scopes in use by default credentials: " + scopes.toString());
		}
	}
	catch (IOException ioe) {
		LOGGER.error("No credentials were found.", ioe);
	}

	return credentialsProvider;
}
 

import com.google.auth.oauth2.ComputeEngineCredentials; //导入依赖的package包/类
@Override
public CredentialOptions build() {
    return CredentialOptions.credential(new ComputeEngineCredentials());
}