如何在Dart客户端中设置gRPC保持连接

dependencies:
  grpc: ^4.1.0
  protobuf: ^3.17.0

protoc --dart_out=grpc:lib example.proto

import 'package:grpc/grpc.dart';
import 'package:example/example.pb.dart';
import 'package:example/example.pbgrpc.dart';

void main() async {
  final channel = ClientChannel(
    'localhost',
    port: 50051,
    options: ChannelOptions(
      credentials: ChannelCredentials.insecure(),
    ),
  );
  final client = ExampleServiceClient(channel);
  
  // 使用client进行gRPC调用
  // ...
  
  await channel.shutdown();
}

final channel = ClientChannel(
  'localhost',
  port: 50051,
  options: ChannelOptions(
    credentials: ChannelCredentials.insecure(),
    keepAlive: Duration(seconds: 30), // 保持连接的间隔
    keepAliveTimeout: Duration(seconds: 10), // 保持连接的超时时间
  ),
);