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
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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:
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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：
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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
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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
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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 providertype 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 actionsfunc (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 requestfunc (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 pathfunc (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 controllerRegistryfunc (api *APIService) RegisterControllers(controllers []interface{}) { for _, v := range controllers { api.RegisterController(v) }} // RegisterControllers is a function registers a controller into controllerRegistryfunc (api *APIService) RegisterController(controller interface{}) { controllerType := getType(controller) api.controllerRegistry[controllerType] = controller} // getType is a function gets the type of valuefunc getType(value interface{}) string { if t := reflect.TypeOf(value); t.Kind() == reflect.Ptr { return "*" + t.Elem().Name() } else { return t.Name() }} // Serve is a functionfunc (api *APIService) Serve(port int) { api.RegisterHandleFunc() fullPort := fmt.Sprintf(":%d", port) http.ListenAndServe(fullPort, nil)} // JSONResponse is a function return json responsefunc (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 userfunc 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，也希望大家多多支持服务器之家。如有错误或未考虑完全的地方，望不吝赐教。
原文链接：https://blog.csdn.net/mengxinghuiku/article/details/65631173
