gRPC安卓/Kotlin快速入门教程-在服务器响应中不可用

implementation 'io.grpc:grpc-android:1.40.0'
implementation 'io.grpc:grpc-okhttp:1.40.0'
implementation 'io.grpc:grpc-protobuf-lite:1.40.0'
implementation 'io.grpc:grpc-stub:1.40.0'

syntax = "proto3";

package com.example.grpc;

service ExampleService {
  rpc SayHello (HelloRequest) returns (HelloResponse) {}
}

message HelloRequest {
  string name = 1;
}

message HelloResponse {
  string message = 1;
}

protoc --java_out=src/main/java example.proto

class ExampleServiceImpl : ExampleServiceGrpc.ExampleServiceImplBase() {
    override fun sayHello(request: HelloRequest, responseObserver: StreamObserver<HelloResponse>) {
        val name = request.name
        val message = "Hello, $name!"
        val response = HelloResponse.newBuilder().setMessage(message).build()
        responseObserver.onNext(response)
        responseObserver.onCompleted()
    }
}

class ExampleClient {
    private val channel: ManagedChannel
    private val stub: ExampleServiceGrpc.ExampleServiceBlockingStub

    init {
        channel = ManagedChannelBuilder.forAddress("localhost", 50051).usePlaintext().build()
        stub = ExampleServiceGrpc.newBlockingStub(channel)
    }

    fun sayHello(name: String): String {
        val request = HelloRequest.newBuilder().setName(name).build()
        val response = stub.sayHello(request)
        return response.message
    }

    fun shutdown() {
        channel.shutdown().awaitTermination(5, TimeUnit.SECONDS)
    }
}

val client = ExampleClient()
val response = client.sayHello("John")
Toast.makeText(this, response, Toast.LENGTH_SHORT).show()
client.shutdown()