HTTP Headers在twirp框架中的使用

1.可以在客户端设置发送带有HTTP Headers的request

func main() {
	client := haberdasher.NewHaberdasherProtobufClient("http://localhost:8080", &http.Client{})
	header := make(http.Header)
	header.Set("Twitch-Authorization", "uDRlDxQYbFVXarBvmTncBoWKcZKqrZTY")
	header.Set("Twitch-Client-ID", "FrankerZ")
	header.Set("Name", "pengjunjie")
	// Attach the headers to a context
	ctx := context.Background()
	ctx, err := twirp.WithHTTPRequestHeaders(ctx, header)
	if err != nil {
		log.Printf("twirp error setting headers: %s", err)
		return
	}
	hat, err := client.MakeHat(ctx, &haberdasher.Size{Inches: 12})
	if err != nil {
		fmt.Printf("oh no: %v", err)
		os.Exit(1)
	}
	fmt.Printf("I have a nice new hat: %+v", hat)
}

分析:通过header.set(key,value)的方法来设自定义设置header中存储的数据，并通过WithHTTPRequestHeaders方法将header整合到context中，再将context作为接口的参数传到服务端

2.可以通过编写中间件来封装服务端

func main() {
	server := &haberdasherserver.Server{} // implements Haberdasher interface
	twirpHandler := haberdasher.NewHaberdasherServer(server, nil)
	wrapped := WithUserAgent(twirpHandler)
	http.ListenAndServe(":8080", wrapped)
}
func WithUserAgent(base http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		ctx := r.Context()
		ua := r.Header.Get("Name")
                fmt.Println("server:" + ua)
		ctx = context.WithValue(ctx, "name", ua)
		r = r.WithContext(ctx)

		base.ServeHTTP(w, r)
	})
}

分析:服务端经过封装后，可以读取到header中的数据，并把读取的数据再一次整合到context，当调用接口时，会把context作为接口实现方法的参数传入

3.接口实现方法读取到context中的数据，并把处理后的结果返回给客户端

func (s *Server) MakeHat(ctx context.Context, size *pb.Size) (hat *pb.Hat, err error) {
	ua := ctx.Value("name").(string)
	log.Printf("name: %v", ua)
	if size.Inches <= 0 {
		return nil, twirp.InvalidArgumentError("inches", "I can't make a hat that small!")
	}
	return &pb.Hat{
		Inches: size.Inches,
		Color:  []string{"white", "black", "brown", "red", "blue"}[rand.Intn(4)],
		Name:   []string{"bowler", "baseball cap", "top hat", "derby"}[rand.Intn(3)],
	}, nil
}

4.测试