【服务计算】gorilla/mux源码分析

0、gorilla/mux

Package gorilla/mux implements a request router and dispatcher for matching incoming requests to their respective handler.

The name mux stands for “HTTP request multiplexer”. Like the standard http.ServeMux, mux.Router matches incoming requests against a list of registered routes and calls a handler for the route that matches the URL or other conditions. The main features are:

• It implements the http.Handler interface so it is compatible with the standard http.ServeMux.
• Requests can be matched based on URL host, path, path prefix, schemes, header and query values, HTTP methods or using custom matchers.
• URL hosts, paths and query values can have variables with an optional regular expression.
• Registered URLs can be built, or “reversed”, which helps maintaining references to resources.
• Routes can be used as subrouters: nested routes are only tested if the parent route matches. This is useful to define groups of routes that share common conditions like a host, a path prefix or other repeated attributes. As a bonus, this optimizes request matching.

1、example

官方文档给出的例子

package main

import (
    "net/http"
    "log"
    "github.com/gorilla/mux"
)

func YourHandler(w http.ResponseWriter, r *http.Request) {
   
   
    w.Write([]byte("Gorilla!\n"))
}

func main() {
   
   
    r := mux.NewRouter()
    // Routes consist of a path and a handler function.
    r.HandleFunc("/", YourHandler)

    // Bind to a port and pass our router in
    log.Fatal(http.ListenAndServe(":8000", r))
}

2、创建路由

让我们依托上面的例子，跟着源码来分析一下mux包如何实现路由创建，路由匹配

首先看到mux.go

// NewRouter returns a new router instance.
func NewRouter() *Router {
   
   
	return &Router{
   
   namedRoutes: make(map[string]*Route), KeepContext: false}
}

我们看到NewRoute()实例化了Router
Router的数据结构如下：
主要由父路由parent，已匹配的路由routes，已命名的路由namedRoutes和三个flagstrictSlash，skipClean，useEncodedPath（相关作用由注释可知）组成

type Router struct {
   
   
	// Configurable Handler to be used when no route matches.
	NotFoundHandler http.Handler

	// Configurable Handler to be used when the request method does not match the route.
	MethodNotAllowedHandler http.Handler

	// Parent route, if this is a subrouter.
	parent parentRoute
	// Routes to be matched, in order.
	routes []*Route
	// Routes by name for URL building.
	namedRoutes map[string]*Route
	// See Router.StrictSlash(). This defines the flag for new routes.
	strictSlash bool
	// See Router.SkipClean(). This defines the flag for new routes.
	skipClean bool
	// If true, do not clear the request context after handling the request.
	// This has no effect when go1.7+ is used, since the context is stored
	// on the request itself.
	KeepContext bool
	// see Router.UseEncodedPath(). This defines a flag for all routes.
	useEncodedPath bool
	// Slice of middlewares to be called after a match is found
	middlewares []middleware
}

// StrictSlash defines the trailing slash behavior for new routes. The initial
// value is false.
//
// When true, if the route path is "/path/", accessing "/path" will perform a redirect
// to the former and vice versa. In other words, your application will always
// see the path as specified in the route.
//