golang 实现一个restful微服务的操作

作者:猫哭 时间:2023-07-06 23:42:13 

如何用net/http构建一个简单的web服务

Golang提供了简洁的方法来构建web服务


package main
import (
   "net/http"
)
func HelloResponse(rw http.ResponseWriter, request *http.Request) {
   fmt.Fprintf(w, "Hello world.")
}
func main() {
   http.HandleFunc("/", HelloResponse)
   http.ListenAndServe(":3000", nil)
}

其中核心的两个方法:

func HandleFunc(pattern string, handler func(ResponseWriter, *Request)):HandleFunc注册一个handler function对应到给定的pattern。

func ListenAndServe(addr string, handler Handler) error:ListenAndServe监听给定的TCP网络地址,接着带上handler调用Serve方法来接收请求。

在go build之后,执行编译后的文件就能在客户端看到hello world了

有了web服务,就可以制定小目标了

我认为作为第一版本,不需要复杂的设计,只需要接收到用户的请求,并且找到对应的handler,执行其逻辑,然后返回JSON响应就好了。

小目标有了,那怎么实现呢?

1.设计用户如何注册Controller和Action

据我观察,一些框架是在Controller里预先设定了GET,POST,PUT等一系列方法,负责接收GET,POST,PUT的HTTP请求。

我认为这样设计的确有其优势,因为用户只需要实现这些方法就好了,但在业务层面也有其劣势,因为我们没有办法保证负责一个页面或者功能的Controller只接收一个GET请求,如果有2个GET请求,那就需要再建立一个Controller,单单实现其GET方法。

因此我借鉴了PHP社区中Laravel注册Controller和Action的语法:Get("/", "IndexController@Index")。

用户只需要定义:


type IndexController struct {
}
func (IndexController *IndexController) Index(//params) (//return values) {
}

当然这样思考后,就给框架带入了一点动态脚本语言的特性,肯定会用到Golang的reflect库。

2.设计Path和Controller还有Action的关系容器

我运用了Golang的map,定义了map[string]map[string]map[string]string这样的数据结构

以["/":["GET":["IndexController":"Get"], "POST":["IndexController":"Post"]], "/foo":["GET":["IndexController":"Foo"]]]举例:

这个说明了在"/"这个PATH下面,有GET和POST请求,分别对应了IndexController下的Get和Post方法,在"/foo"这个PATH下面,有GET请求,对应IndexController下的Foo方法。

在接受请求时候,如果没有找到对应的方法,就返回405。

3.如何将注册了的一系列Method与PATH绑定来接收外部请求

我们可以看到,func HandleFunc(pattern string, handler func(ResponseWriter, *Request))要求的handler类型是func(ResponseWriter, *Request)),这和我们设计的functionfunc (IndexController *IndexController) Index(//params) (//return values) {}有所差距。

这时候我发现由于Golang具备First Class Functions特性,因此我们可以将函数做如下处理:


http.HandleFunc(path, HandleRequest())
func HandleRequest() {
   return func(rw http.ResponseWriter, request *http.Request) {
       // do your logic
   }
}

4.和encoding/json说Hi

当我们接收到function的返回值后,我们就需要对结果进行json encode,而encoding/json正是负责这个功能。 我用的是json.Marshal():

func Marshal(v interface{}) ([]byte, error): Marshal返回v的encoding结果。

如何使用


package main
import (
   "net/url"
   "net/http"
   "github.com/ZhenhangTung/GoGym"
)
type IndexController struct {
}
func (IndexController *IndexController) Index(request map[string]url.Values, headers http.Header) (statusCode int, response interface{}) {
   return 200, map[string]string{"hello": "world"}
}
type BarController struct {
}
func (*BarController) Bar(request map[string]url.Values, headers http.Header) (statusCode int, response interface{}, responseHeader http.Header) {
   return 200, map[string]string{"GoTo": "Bar"}, http.Header{"Foo": {"Bar", "Baz"}}
}
func main() {
   var apiService = GoGym.Prepare()
   apiService.Get("index", "IndexController@Index")
   apiService.Post("bar", "BarController@Bar")
   controllers := []interface{}{&IndexController{}}
   apiService.RegisterControllers(controllers)
   apiService.RegisterController(&BarController{})
   apiService.Serve(3000)
}

项目完整代码


package GoGym
import (
   "encoding/json"
   "fmt"
   "net/http"
   "net/url"
   "reflect"
   "strings"
)
const (
   GETMethod     = "GET"
   POSTMethod    = "POST"
   PUTMethod     = "PUT"
   PATCHMethod   = "PATCH"
   DELETEMethod  = "DELETE"
   OPTIONSMethod = "OPTIONS"
)
const (
   HTTPMethodNotAllowed = 405
)
// APIService for now is the struct for containing controllerRegistry and registeredPathAndController,
// and it is the core service provider
type APIService struct {
   // controllerRegistry is where all registered controllers exist
   controllerRegistry map[string]interface{}
   //registeredPathAndController is a mapping of paths and controllers
   registeredPathAndController map[string]map[string]map[string]string
   requestForm                 map[string]url.Values
}
func (api *APIService) Get(path, controllerWithActionString string) {
   mapping := api.mappingRequestMethodWithControllerAndActions(GETMethod, path, controllerWithActionString)
   api.registeredPathAndController[path] = mapping
}
func (api *APIService) Post(path, controllerWithActionString string) {
   mapping := api.mappingRequestMethodWithControllerAndActions(POSTMethod, path, controllerWithActionString)
   api.registeredPathAndController[path] = mapping
}
func (api *APIService) Put(path, controllerWithActionString string) {
   mapping := api.mappingRequestMethodWithControllerAndActions(PUTMethod, path, controllerWithActionString)
   api.registeredPathAndController[path] = mapping
}
func (api *APIService) Patch(path, controllerWithActionString string) {
   mapping := api.mappingRequestMethodWithControllerAndActions(PATCHMethod, path, controllerWithActionString)
   api.registeredPathAndController[path] = mapping
}
func (api *APIService) Options(path, controllerWithActionString string) {
   mapping := api.mappingRequestMethodWithControllerAndActions(OPTIONSMethod, path, controllerWithActionString)
   api.registeredPathAndController[path] = mapping
}
func (api *APIService) Delete(path, controllerWithActionString string) {
   mapping := api.mappingRequestMethodWithControllerAndActions(DELETEMethod, path, controllerWithActionString)
   api.registeredPathAndController[path] = mapping
}
// mappingRequestMethodWithControllerAndActions is a function for mapping request method with controllers
// which containing actions
func (api *APIService) mappingRequestMethodWithControllerAndActions(requestMethod, path, controllerWithActionString string) map[string]map[string]string {
   mappingResult := make(map[string]map[string]string)
   if length := len(api.registeredPathAndController[path]); length > 0 {
       mappingResult = api.registeredPathAndController[path]
   }
   controllerAndActionSlice := strings.Split(controllerWithActionString, "@")
   controller := controllerAndActionSlice[0]
   action := controllerAndActionSlice[1]
   controllerAndActionMap := map[string]string{controller: action}
   mappingResult[requestMethod] = controllerAndActionMap
   return mappingResult
}
// HandleRequest is a function to handle http request
func (api *APIService) HandleRequest(controllers map[string]map[string]string) http.HandlerFunc {
   return func(rw http.ResponseWriter, request *http.Request) {
       request.ParseForm()
       method := request.Method
       api.requestForm["query"] = request.Form
       api.requestForm["form"] = request.PostForm
       macthedControllers, ok := controllers[method]
       if !ok {
           rw.WriteHeader(HTTPMethodNotAllowed)
       }
       for k, v := range macthedControllers {
           controllerKey := "*" + k
           controller := api.controllerRegistry[controllerKey]
           in := make([]reflect.Value, 2)
           in[0] = reflect.ValueOf(api.requestForm)
           in[1] = reflect.ValueOf(request.Header)
           returnValues := reflect.ValueOf(controller).MethodByName(v).Call(in)
           statusCode := returnValues[0].Interface()
           intStatusCode := statusCode.(int)
           response := returnValues[1].Interface()
           responseHeaders := http.Header{}
           if len(returnValues) == 3 {
               responseHeaders = returnValues[2].Interface().(http.Header)
           }
           api.JSONResponse(rw, intStatusCode, response, responseHeaders)
       }
   }
}
// RegisterHandleFunc is a function registers a handle function to handle request from path
func (api *APIService) RegisterHandleFunc() {
   for k, v := range api.registeredPathAndController {
       path := k
       if !strings.HasPrefix(k, "/") {
           path = fmt.Sprintf("/%v", k)
       }
       http.HandleFunc(path, api.HandleRequest(v))
   }
}
// RegisterControllers is a function registers a struct of controllers into controllerRegistry
func (api *APIService) RegisterControllers(controllers []interface{}) {
   for _, v := range controllers {
       api.RegisterController(v)
   }
}
// RegisterControllers is a function registers a controller into controllerRegistry
func (api *APIService) RegisterController(controller interface{}) {
   controllerType := getType(controller)
   api.controllerRegistry[controllerType] = controller
}
// getType is a function gets the type of value
func getType(value interface{}) string {
   if t := reflect.TypeOf(value); t.Kind() == reflect.Ptr {
       return "*" + t.Elem().Name()
   } else {
       return t.Name()
   }
}
// Serve is a function
func (api *APIService) Serve(port int) {
   api.RegisterHandleFunc()
   fullPort := fmt.Sprintf(":%d", port)
   http.ListenAndServe(fullPort, nil)
}
// JSONResponse is a function return json response
func (api *APIService) JSONResponse(rw http.ResponseWriter, statusCode int, response interface{}, headers http.Header) {
   for k, v := range headers {
       for _, header := range v {
           rw.Header().Add(k, header)
       }
   }
   rw.Header().Add("Content-Type", "application/json")
   rw.WriteHeader(statusCode)
   rsp, err := json.Marshal(response)
   if err != nil {
       // TODO: logging error
       fmt.Println("JSON err:", err)
   }
   rw.Write(rsp)
}
// Prepare is a fucntion prepare the service and return prepared service to the user
func Prepare() *APIService {
   var apiService = new(APIService)
   apiService.controllerRegistry = make(map[string]interface{})
   apiService.registeredPathAndController = make(map[string]map[string]map[string]string)
   apiService.requestForm = make(map[string]url.Values)
   return apiService
}

以上为个人经验,希望能给大家一个参考

来源:https://blog.csdn.net/mengxinghuiku/article/details/65631173

标签:golang,restful,微服务
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