1.go-kit 介绍

go-kit是一个分布式的开发工具集，在大型的组织（业务）中可以用来构建微服务，其解决了分布式系统中大多数常见问题，因此，使用者可以将精力集中在业务逻辑上。

他里面有用来帮助我们实现微服务的一些工具包, 和SpringBoot不同, 直接把框架搭好, 而需要手动的搭框架。go-kit 也存在3层架构。

微服务就是一个大项目中的一个小功能块，并且这个功能块可以不计语言差别的和其他功能模块通过API进行通讯和结合。

1.1 go-kit 三层结构

go-kit和SSM中的MVC一样也有三层结构endpoint，service, transport，通过这三层结构来实现，接收一个请求，然后返回一个结果。

1. Transport
   Transport处于该微服务的最上层，主要负责于HTTP, gRPC，thrift等相关的逻辑，负责解析请求，并且调用endpoint来处理请求

2. Endpoint
   endpoint属于客户端和服务端的转接器，他定义了request和response的格式，上层给Transport调用来处理请求，下层链接Service将Service所返回的结果转换成request需要的格式

3. Service
   最底下的我们这个模块所需要实现的功能了

2.go-kit 实例

service -> endpoint -> transport

service.go

package serviceimport ("errors""strings"
)type StringServiceI interface {GetUppercase(string) (string, error)PostUppercase(string) (string, error)GetCount(string) int
}type StringService struct {
}func (StringService) GetUppercase(s string) (string, error) {if s == "" {return "", errors.New("error")}return strings.ToUpper(s), nil
}func (StringService) PostUppercase(s string) (string, error) {if s == "" {return "", errors.New("error")}return strings.ToUpper(s), nil
}func (StringService) GetCount(s string) (int, error) {if s == "" {return 0, errors.New("error")}return len(s), nil
}

endpoint.go

package endpointimport ("context""github.com/go-kit/kit/endpoint""go-demo06/service"
)type Endpoints struct {GetUppercase  endpoint.EndpointPostUppercase endpoint.EndpointGetCount      endpoint.Endpoint
}type UppercaseRequest struct {S string `json:"s"`
}type UppercaseResponse struct {V   string `json:"v"`Err error  `json:"err"`
}type CountRequest struct {S string `json:"s"`
}type CountResponse struct {V int `json:"v"`
}func MakeEndpoints(svc service.StringService) Endpoints {return Endpoints{GetCount:      MakeGetCountEndpoint(svc),GetUppercase:  MakeGetUppercaseEndpoint(svc),PostUppercase: MakePostUppercaseEndpoint(svc),}
}func MakeGetUppercaseEndpoint(svc service.StringService) endpoint.Endpoint {return func(ctx context.Context, request interface{}) (response interface{}, err error) {req := request.(UppercaseRequest)v, err := svc.GetUppercase(req.S)if err != nil {return UppercaseResponse{v, err}, nil}return UppercaseResponse{v, err}, nil}
}func MakePostUppercaseEndpoint(svc service.StringService) endpoint.Endpoint {return func(ctx context.Context, request interface{}) (response interface{}, err error) {req := request.(UppercaseRequest)v, err := svc.PostUppercase(req.S)if err != nil {return UppercaseResponse{v, err}, nil}return UppercaseResponse{v, err}, nil}
}func MakeGetCountEndpoint(svc service.StringService) endpoint.Endpoint {return func(ctx context.Context, request interface{}) (response interface{}, err error) {req := request.(CountRequest)v, err := svc.GetCount(req.S)if err != nil {return CountResponse{v}, nil}return CountResponse{v}, nil}
}

rest.go

package transportimport ("context""encoding/json"httptransport "github.com/go-kit/kit/transport/http""github.com/gorilla/mux""go-demo06/endpoint""go-demo06/service""log""net/http"
)func RestRun() {svc := service.StringService{}r := makeHttpHandler(svc)log.Fatal(http.ListenAndServe(":8080", r))
}func makeHttpHandler(svc service.StringService) http.Handler {r := mux.NewRouter()e := endpoint.MakeEndpoints(svc)r.Methods("GET").Path("/uppercase").Handler(httptransport.NewServer(e.GetUppercase, DecodeUppercaseRequest, EncodeUppercaseResponse))r.Methods("GET").Path("/count").Handler(httptransport.NewServer(e.GetCount, DecodeCountRequest, EncodeCountResponse))return r
}func DecodeUppercaseRequest(_ context.Context, r *http.Request) (interface{}, error) {var req endpoint.UppercaseRequestif err := json.NewDecoder(r.Body).Decode(&req); err != nil {return nil, err}return req, nil
}func EncodeUppercaseResponse(_ context.Context, w http.ResponseWriter, response interface{}) error {// transport body to jsonw.Header().Set("Content-type", "application/json")return json.NewEncoder(w).Encode(response)
}func DecodeCountRequest(_ context.Context, r *http.Request) (interface{}, error) {var req endpoint.CountRequestif err := json.NewDecoder(r.Body).Decode(&req); err != nil {return nil, err}return req, nil
}func EncodeCountResponse(_ context.Context, w http.ResponseWriter, response interface{}) error {// transport body to jsonw.Header().Set("Content-type", "application/json")return json.NewEncoder(w).Encode(response)
}

main.go

package mainimport ("go-demo06/transport"
)func main() {transport.RestRun()
}

go run main.go