GoLang的反思错误 - 参数太少(Reflection error on GoLang - Too few arguments)
我有这个控制器：
package web import ( "net/http" ) func init() { } func (controller *Controller) Index(r *http.Request) (string, int) { return "Testing", http.StatusOK }使用此处理程序：
type Application struct { } func (application *Application) Route(controller interface{}, route string) http.HandlerFunc { return func(w http.ResponseWriter, r *http.Request) { var ptr reflect.Value var value reflect.Value var finalMethod reflect.Value value = reflect.ValueOf(controller) // if we start with a pointer, we need to get value pointed to // if we start with a value, we need to get a pointer to that value if value.Type().Kind() == reflect.Ptr { ptr = value value = ptr.Elem() } else { ptr = reflect.New(reflect.TypeOf(controller)) temp := ptr.Elem() temp.Set(value) } // check for method on value method := value.MethodByName(route) if method.IsValid() { finalMethod = method } // check for method on pointer method = ptr.MethodByName(route) if method.IsValid() { finalMethod = method } methodInterface := finalMethod.Call([]reflect.Value{})[0].Interface() method_route := methodInterface.(func(r *http.Request) (string, int)) body, code := method_route(r) switch code { case http.StatusOK: io.WriteString(w, body) case http.StatusSeeOther, http.StatusFound: http.Redirect(w, r, body, code) default: w.WriteHeader(code) io.WriteString(w, body) } } }它以这种方式执行：
controller := &web.Controller{} application := &system.Application{} http.HandleFunc("/", application.Route(controller, "Index"))问题是编译好了。 它没有显示任何错误，但是当我访问网站时，只需指向localhost即可显示：
2014/12/27 22:38:16 http: panic serving 127.0.0.1:58304: reflect: Call with too few input arguments goroutine 20 [running]: net/http.func·011() /usr/local/Cellar/go/1.3.3/libexec/src/pkg/net/http/server.go:1100 +0xb7我找不到任何错误，更奇怪的是它编译好了......我是Go的新手，所以我不知道发生了什么......
I have this controller:
package web import ( "net/http" ) func init() { } func (controller *Controller) Index(r *http.Request) (string, int) { return "Testing", http.StatusOK }With this handler:
type Application struct { } func (application *Application) Route(controller interface{}, route string) http.HandlerFunc { return func(w http.ResponseWriter, r *http.Request) { var ptr reflect.Value var value reflect.Value var finalMethod reflect.Value value = reflect.ValueOf(controller) // if we start with a pointer, we need to get value pointed to // if we start with a value, we need to get a pointer to that value if value.Type().Kind() == reflect.Ptr { ptr = value value = ptr.Elem() } else { ptr = reflect.New(reflect.TypeOf(controller)) temp := ptr.Elem() temp.Set(value) } // check for method on value method := value.MethodByName(route) if method.IsValid() { finalMethod = method } // check for method on pointer method = ptr.MethodByName(route) if method.IsValid() { finalMethod = method } methodInterface := finalMethod.Call([]reflect.Value{})[0].Interface() method_route := methodInterface.(func(r *http.Request) (string, int)) body, code := method_route(r) switch code { case http.StatusOK: io.WriteString(w, body) case http.StatusSeeOther, http.StatusFound: http.Redirect(w, r, body, code) default: w.WriteHeader(code) io.WriteString(w, body) } } }And it is executed in this way:
controller := &web.Controller{} application := &system.Application{} http.HandleFunc("/", application.Route(controller, "Index"))The problem is it compiled ok. It does not show any error, but when I go to the website, just by pointing at localhost, it shows:
2014/12/27 22:38:16 http: panic serving 127.0.0.1:58304: reflect: Call with too few input arguments goroutine 20 [running]: net/http.func·011() /usr/local/Cellar/go/1.3.3/libexec/src/pkg/net/http/server.go:1100 +0xb7I cannot find any error, and it is more strange it compiles ok... I'm new in Go, so I've no idea what is going on...
最满意答案
我通过阅读这个找到了答案：
https://stackoverflow.com/a/20715067/1339973
所以不要试图调用方法：
methodInterface := finalMethod.Call([]reflect.Value{})[0].Interface() method_route := methodInterface.(func(r *http.Request) (string, int)) body, code := method_route(r)我只是获得了我需要的接口，然后将其转换为函数并将其调用。
methodInterface := finalMethod.Interface() method_route := methodInterface.(func(r *http.Request) (string, int)) body, code := method_route(r)实际上，这就是我已经在做的事情，但是方式错误。
I have found the answer by reading this:
https://stackoverflow.com/a/20715067/1339973
So instead of trying to call the method:
methodInterface := finalMethod.Call([]reflect.Value{})[0].Interface() method_route := methodInterface.(func(r *http.Request) (string, int)) body, code := method_route(r)I just get the interface I need, then convert it into a function and call it as such.
methodInterface := finalMethod.Interface() method_route := methodInterface.(func(r *http.Request) (string, int)) body, code := method_route(r)Actually, that is kind of what I was already doing, but in the wrong way.
更多推荐
发布评论