1. proto

syntax = "proto3";
option go_package = ".;proto";
service Greeter {
    rpc SayHello (HelloRequest) returns (HelloReply);
}
message HelloRequest {
    string name = 1;
}
message HelloReply {
    string message = 1;
}

2. 服务端

package main
import (
    "context"
    "fmt"
    "google.golang.org/grpc/codes"
    "google.golang.org/grpc/metadata"
    "google.golang.org/grpc/status"
    "net"
    "google.golang.org/grpc"
    "start/token_interceptor/proto"
)
type Server struct{}
func (s *Server) SayHello(ctx context.Context, request *proto.HelloRequest) (*proto.HelloReply,
    error){
    return &proto.HelloReply{
        Message: "hello "+request.Name,
    }, nil
}
func main(){
    lis, err := net.Listen("tcp", ":50051")
    if err != nil {
        fmt.Println(err.Error())
        return
    }
    var interceptor grpc.UnaryServerInterceptor
    interceptor = func(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (resp interface{}, err error) {
        md, ok := metadata.FromIncomingContext(ctx)
        if !ok {
            return resp, status.Errorf(codes.Unauthenticated, "无Token认证信息")
        }
        var (
            appid  string
            appkey string
        )
        if val, ok := md["appid"]; ok {
            appid = val[0]
        }
        if val, ok := md["appkey"]; ok {
            appkey = val[0]
        }
        if appid != "golangblogs" || appkey != "good good study" {
            return resp, status.Errorf(codes.Unauthenticated, "Token认证信息无效: appid=%s, appkey=%s", appid, appkey)
        }
        // 继续处理请求
        return handler(ctx, req)
    }
    var opts []grpc.ServerOption
    opts = append(opts, grpc.UnaryInterceptor(interceptor))
    s := grpc.NewServer(opts...)
    ser :=& Server{}
    proto.RegisterGreeterServer(s, ser)
    s.Serve(lis)
}

3. 客户端

package  main
import (
    "context"
    "fmt"
    "google.golang.org/grpc"
    "start/token_interceptor/proto"
)
type customCredential struct{}
func (c customCredential) GetRequestMetadata(ctx context.Context, uri ...string) (map[string]string, error) {
    return map[string]string{
        "appid":  "golangblogs",
        "appkey": "good good study",
    }, nil
}
func (c customCredential) RequireTransportSecurity() bool {
    return false
}
func main() {
    var opts []grpc.DialOption
    //opts = append(opts, grpc.WithUnaryInterceptor(interceptor))
    opts = append(opts, grpc.WithInsecure())
    opts = append(opts, grpc.WithPerRPCCredentials(new(customCredential)))
    // 指定客户端interceptor
    conn, err := grpc.Dial("localhost:50051", opts...)
    if err != nil {
        panic(err)
    }
    defer conn.Close()
    c := proto.NewGreeterClient(conn)
    //rsp, _ := c.Search(context.Background(), &empty.Empty{})
    rsp, err := c.SayHello(context.Background(), &proto.HelloRequest{
        Name: "叶良辰",
    })
    if err != nil {
        panic(err)
    }
    fmt.Println(rsp.Message)
}