net/http 处理错误的一般流程如下:
func main() {
mux := http.NewServeMux()
mux.HandleFunc("GET /hello", helloHandler)
http.ListenAndServe(":8080", mux)
}
func helloHandler(w http.ResponseWriter, r *http.Request) {
condition := false
if !condition {
http.Error(w, "bad reqeust", http.StatusBadRequest)
return
}
fmt.Fprintf(w, "hello world")
}设想一下，你在使用net/http 时，想添加错误集中处理的功能。
那么helloHandler就必须返回一个error
func helloHandlerWithErr(w http.ResponseWriter, r *http.Request) error {
condition := false
if !condition {
return fmt.Errorf("condition is false")
}
fmt.Fprintf(w, "hello world")
return nil
}可是http.HandleFunc只接受func(http.ResponseWriter, *http.Request)签名的handler函数:
HandleFunc(pattern string, handler func(http.ResponseWriter, *http.Request))你想到了写一个适配器，把
type HandlerFunc func(http.ResponseWriter, *http.Request) error转化成
type HttpHandlerFunc func(http.ResponseWriter, *http.Request)动手实现，你在适配器中进行集中错误处理:
func Adator(fn HandlerFunc) HttpHandlerFunc {
return func(w http.ResponseWriter, r *http.Request) {
err := fn(w, r)
// 集中错误处理
if err != nil {
http.Error(w, err.Error(), http.StatusBadRequest)
}
}
}你已经实现了集中错误处理，但是需要你使用Adator对每个HanderFunc进行包裹:
mux.HandleFunc("GET /hello", Adator(helloHandlerWithErr))这是很繁琐的，我们需要进一步优化。
创建一个结构体ServeMux它嵌入了http.ServeMux:
type ServeMux struct {
http.ServeMux
}重写ServeMux的HandleFunc方法, 它接收HandlerFunc而不是原来的HttpHandlerFunc：
func (m *ServeMux) HandleFunc(pattern string, handler HandlerFunc) {
m.ServeMux.HandleFunc(pattern, func(w http.ResponseWriter, r *http.Request) {
err := handler(w, r)
if err != nil {
http.Error(w, "some msg", http.StatusBadRequest)
}
})
}这样就不需要使用Adator进行包裹了。完整的实现在
https://github.com/aeilang/httpz/blob/main/http.go