Golang装饰器模式扩展HTTP处理功能

func loggingMiddleware(next http.HandlerFunc) http.HandlerFunc {
    return func(w http.ResponseWriter, r *http.Request) {
        log.Printf("%s %s", r.Method, r.URL.Path)
        next(w, r)
    }
}

http.HandleFunc("/api/data", loggingMiddleware(dataHandler))

func authMiddleware(next http.HandlerFunc) http.HandlerFunc {
    return func(w http.ResponseWriter, r *http.Request) {
        token := r.Header.Get("Authorization")
        if token == "" {
            http.Error(w, "Unauthorized", http.StatusUnauthorized)
            return
        }
        next(w, r)
    }
}
<p>func timeoutMiddleware(next http.HandlerFunc) http.HandlerFunc {
return func(w http.ResponseWriter, r <em>http.Request) {
ctx, cancel := context.WithTimeout(r.Context(), 5</em>time.Second)
defer cancel()
r = r.WithContext(ctx)
done := make(chan bool, 1)
go func() {
next(w, r)
done <- true
}()
select {
case <-done:
case <-ctx.Done():
http.Error(w, "Request timeout", http.StatusGatewayTimeout)
}
}
}</p>

handler := loggingMiddleware(authMiddleware(timeoutMiddleware(dataHandler)))
http.HandleFunc("/api/data", handler)

type Middleware func(http.HandlerFunc) http.HandlerFunc
<p>func chainMiddleware(handlers ...Middleware) Middleware {
return func(https://www.php.cn/link/671ee9fb86338a4643eb6d3f2d00496c http.HandlerFunc) http.HandlerFunc {
for i := len(handlers) - 1; i >= 0; i-- {
https://www.php.cn/link/671ee9fb86338a4643eb6d3f2d00496c = handlers<a href="https://www.php.cn/link/671ee9fb86338a4643eb6d3f2d00496c">i</a>
}
return https://www.php.cn/link/671ee9fb86338a4643eb6d3f2d00496c
}
}</p>

middlewareChain := chainMiddleware(loggingMiddleware, authMiddleware, timeoutMiddleware)
http.HandleFunc("/api/data", middlewareChain(dataHandler))