grpc client 报错: code = Unimplemented desc = method *** not implemented

syntax = "proto3";
option go_package = "/grpcT;grpcT";
package grpcT;
service GrpcService {
  rpc Fun(RequestData) returns (ResponseData){}
}
message RequestData {
  string repT = 1;
  int64 r = 2;
}

message ResponseData {
  string resT = 1;
  int64 code = 2;
}

protoc --go_out=plugins=grpc:.grpcT.proto

或者 protoc --go_out=. --go_opt=paths=source_relative --go-grpc_out=. --go-grpc_opt=paths=source_relative ./grpcT.proto

package main

import (
	"context"
	"fmt"
	"log"
	"net"

	pb "studyGo/grpcServer/grpcT"

	"google.golang.org/grpc"
)

const (
	port = ":50051"
)

type server struct { //服务的结构类型
	*pb.UnimplementedGrpcServiceServer
}

func (s *server) Fun(ctx context.Context, in *pb.RequestData) (*pb.ResponseData, error) {
	fmt.Println("-------%d,===%s", in.R, in.RepT)
	return &pb.ResponseData{ResT: "aaa", Code: 200}, nil
}

func (s *server) A(ctx context.Context, in *pb.RequestData) (*pb.ResponseData, error) {
	fmt.Println("-------%d,===%s", in.R, in.RepT)
	return &pb.ResponseData{ResT: "aaa", Code: 200}, nil
}

func main() {
	lis, err := net.Listen("tcp", port) //开启监听
	if err != nil {
		log.Fatalf("failed to listen: %v", err)
	}
	s := grpc.NewServer()                      //新建一个grpc服务
	pb.RegisterGrpcServiceServer(s, &server{}) //这个服务和上述的服务结构联系起来，这样你新建的这个服务里面就有那些类型的方法
	if err := s.Serve(lis); err != nil {       //这个服务和你的监听联系起来，这样外界才能访问到啊
		log.Fatalf("failed to serve: %v", err)
	}
}

package main

import (
    "context"
    "fmt"
    "log"
    "time"

    pb "studyGo/grpcServer/grpcT"

    "google.golang.org/grpc"
)

const (
    address = "localhost:50051"
)

func main() {
    conn, err := grpc.Dial(address, grpc.WithInsecure(), grpc.WithBlock())
    if err != nil {
        log.Fatalf("did not connect: %v", err)
    }
    defer conn.Close()
    c := pb.NewGrpcServiceClient(conn) //返回一个client连接，通过这个连接就可以访问到对应的服务资源，就像一个对象
    // Contact the server and print out its response.
    ctx, cancel := context.WithTimeout(context.Background(), 4*time.Second) //返回一个client，并设置超时时间
    defer cancel()
    r, err := c.Fun(ctx, &pb.RequestData{RepT: "aaa", R: int64(10)}) //访问对应的服务器上面的服务方法
    if err != nil {
        log.Fatalf("could not rpc: %v,%T", err, c)
    }
    fmt.Println(fmt.Sprintf("%v", r))
}