1. proto

syntax = "proto3";
option go_package = ".;proto";
service Greeter {
    rpc SayHello (HelloRequest) returns (HelloReply);
}
//将 sessionid放入 放入cookie中 http协议
message HelloRequest {
    string name = 1;
}
message HelloReply {
    string message = 1;
}

2. 客户端

package main
import (
    "context"
    "fmt"
    "google.golang.org/grpc"
    "time"
    "start/grpc_interceptor/proto"
)
func interceptor(ctx context.Context, method string, req, reply interface{}, cc *grpc.ClientConn, invoker grpc.UnaryInvoker, opts ...grpc.CallOption) error {
    start := time.Now()
    err := invoker(ctx, method, req, reply, cc, opts...)
    fmt.Printf("method=%s req=%v rep=%v duration=%s error=%v\n", method, req, reply, time.Since(start), err)
    return err
}
func main(){
    //stream
    var opts []grpc.DialOption
    opts = append(opts, grpc.WithInsecure())
    // 指定客户端interceptor
    opts = append(opts, grpc.WithUnaryInterceptor(interceptor))
    conn, err := grpc.Dial("localhost:50051", opts...)
    if err != nil {
        panic(err)
    }
    defer conn.Close()
    c := proto.NewGreeterClient(conn)
    r, err := c.SayHello(context.Background(), &proto.HelloRequest{Name:"bobby"})
    if err != nil {
        panic(err)
    }
    fmt.Println(r.Message)
}

3. 服务端

package main
import (
    "context"
    "fmt"
    "net"
    "google.golang.org/grpc"
    "start/grpc_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(){
    var interceptor grpc.UnaryServerInterceptor
    interceptor = func(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (resp interface{}, err error) {
        // 继续处理请求
        fmt.Println("接收到新请求")
        res, err := handler(ctx, req)
        fmt.Println("请求处理完成")
        return res, err
    }
    var opts []grpc.ServerOption
    opts = append(opts, grpc.UnaryInterceptor(interceptor))
    g := grpc.NewServer(opts...)
    proto.RegisterGreeterServer(g, &Server{})
    lis, err := net.Listen("tcp", "0.0.0.0:50051")
    if err != nil{
        panic("failed to listen:"+err.Error())
    }
    err = g.Serve(lis)
    if err != nil{
        panic("failed to start grpc:"+err.Error())
    }
}

4. 拦截器的应用场景

go-grpc-middleware