io.grpc.ManagedChannelBuilder#forTarget ( )源码实例Demo

/**
 * Constructs a new instance of the exporter based on the builder's values.
 *
 * @return a new exporter's instance
 */
public OtlpGrpcSpanExporter build() {
  if (endpoint != null) {
    final ManagedChannelBuilder<?> managedChannelBuilder =
        ManagedChannelBuilder.forTarget(endpoint);

    if (useTls) {
      managedChannelBuilder.useTransportSecurity();
    } else {
      managedChannelBuilder.usePlaintext();
    }

    if (metadata != null) {
      managedChannelBuilder.intercept(MetadataUtils.newAttachHeadersInterceptor(metadata));
    }

    channel = managedChannelBuilder.build();
  }
  return new OtlpGrpcSpanExporter(channel, deadlineMs);
}
 

/** Sets up the SSL provider and configures the gRPC channel. */
private ManagedChannel initChannel(Context context, DatabaseInfo databaseInfo) {
  try {
    // We need to upgrade the Security Provider before any network channels are initialized.
    // `OkHttp` maintains a list of supported providers that is initialized when the JVM first
    // resolves the static dependencies of ManagedChannel.
    ProviderInstaller.installIfNeeded(context);
  } catch (GooglePlayServicesNotAvailableException /* Thrown by ProviderInstaller */
      | GooglePlayServicesRepairableException /* Thrown by ProviderInstaller */
      | IllegalStateException e /* Thrown by Robolectric */) {
    // Mark the SSL initialization as done, even though we may be using outdated SSL
    // ciphers. gRPC-Java recommends obtaining updated ciphers from GMSCore, but we allow
    // the device to fall back to other SSL ciphers if GMSCore is not available.
    Logger.warn(LOG_TAG, "Failed to update ssl context: %s", e);
  }

  ManagedChannelBuilder<?> channelBuilder;
  if (overrideChannelBuilderSupplier != null) {
    channelBuilder = overrideChannelBuilderSupplier.get();
  } else {
    channelBuilder = ManagedChannelBuilder.forTarget(databaseInfo.getHost());
    if (!databaseInfo.isSslEnabled()) {
      // Note that the boolean flag does *NOT* switch the wire format from Protobuf to Plaintext.
      // It merely turns off SSL encryption.
      channelBuilder.usePlaintext();
    }
  }

  // Ensure gRPC recovers from a dead connection. (Not typically necessary, as the OS will
  // usually notify gRPC when a connection dies. But not always. This acts as a failsafe.)
  channelBuilder.keepAliveTime(30, TimeUnit.SECONDS);

  // Wrap the ManagedChannelBuilder in an AndroidChannelBuilder. This allows the channel to
  // respond more gracefully to network change events (such as switching from cell to wifi).
  AndroidChannelBuilder androidChannelBuilder =
      AndroidChannelBuilder.usingBuilder(channelBuilder).context(context);

  return androidChannelBuilder.build();
}
 

/**
 * Returns a new gRPC ManagedChannelBuilder with instrumentation.
 */
public ManagedChannelBuilder<?> newManagedChannelBuilder(String target) {
  final ManagedChannelBuilder<?> builder = ManagedChannelBuilder.forTarget(target);
  addDefaultBuilderProperties(builder);

  return builder;
}
 

private static void startClient() {
    final TestApplication application = DROPWIZARD.getApplication();
    final ManagedChannelBuilder<?> localhost =
            ManagedChannelBuilder.forTarget("localhost:" + application.getServer().getPort());
    channel = localhost.usePlaintext().build();
    client = PersonServiceGrpc.newBlockingStub(channel);
}
 

/**
 * Creates a channel to the first server in the given list.
 */
@Override
ManagedChannel createChannel(List<ServerInfo> servers) {
  checkArgument(!servers.isEmpty(), "No management server provided.");
  XdsLogger logger = XdsLogger.withPrefix("xds-client-channel-factory");
  ServerInfo serverInfo = servers.get(0);
  String serverUri = serverInfo.getServerUri();
  logger.log(XdsLogLevel.INFO, "Creating channel to {0}", serverUri);
  List<ChannelCreds> channelCredsList = serverInfo.getChannelCredentials();
  ManagedChannelBuilder<?> channelBuilder = null;
  // Use the first supported channel credentials configuration.
  // Currently, only "google_default" is supported.
  for (ChannelCreds creds : channelCredsList) {
    if (creds.getType().equals("google_default")) {
      logger.log(XdsLogLevel.INFO, "Using channel credentials: google_default");
      channelBuilder = GoogleDefaultChannelBuilder.forTarget(serverUri);
      break;
    }
  }
  if (channelBuilder == null) {
    logger.log(XdsLogLevel.INFO, "Using default channel credentials");
    channelBuilder = ManagedChannelBuilder.forTarget(serverUri);
  }

  return channelBuilder
      .keepAliveTime(5, TimeUnit.MINUTES)
      .build();
}
 

public ManagedChannelBuilder<?> forTarget(String target) {
	ManagedChannelBuilder<?> builder = ManagedChannelBuilder.forTarget(target);
	customize(builder);
	return builder;
}