什么是http请求多路复用器？

Question

I've been studying golang and I noticed a lot of people create servers by using the http.NewServeMux() function and I don't really understand what it does.

I read this:

In go ServeMux is an HTTP request multiplexer. It matches the URL of each incoming request against a list of registered patterns and calls the handler for the pattern that most closely matches the URL.

How is that different than just doing something like:

http.ListenAndServe(addr, nil)
http.Handle("/home", home)
http.Handle("/login", login)

What is the purpose of using multiplexing?

Answer 1

From net/http GoDoc and Source.

ListenAndServe starts an HTTP server with a given address and handler. The handler is usually nil, which means to use DefaultServeMux. Handle and HandleFunc add handlers to DefaultServeMux

DefaultServeMux is just a predefined http.ServeMux

var DefaultServeMux = &defaultServeMux
var defaultServeMux ServeMux

As you can see http.Handle calls DefaultServeMux internally.

func Handle(pattern string, handler Handler) { DefaultServeMux.Handle(pattern, handler) }

The purpose of http.NewServeMux() is to have your own instance of http.Servermux for instances like when you require two http.ListenAndServe functions listening to different ports with different routes.