学习Go语言动手写Web框架-day0

最近在学习golang想自己跟着教程做项目，看到geektutu的教程非常nice，就跟着学习一下。geektutu学习项目地址d

由于之前有了解golang的语法，所以代码还是能够看懂。

Base1 讲到使用golang本身的net/http库实现了2个路由，分别绑定了两个不同的函数，用来发送不同的内容。

 main.go 

package main

import (
	"fmt"
	"log"
	"net/http"
)

func main() {
	http.HandleFunc("/",indexHandler)
	http.HandleFunc("/hello",helloHandler)
	log.Fatal(http.ListenAndServe(":9999",nil))
}

func indexHandler(w http.ResponseWriter, req *http.Request) {
	fmt.Fprintf(w,"URL.Path = %q\n",req.URL.Path)
}

func helloHandler(w http.ResponseWriter,req *http.Request) {
	for k, v := range req.Header  {
		fmt.Fprintf(w,"Header[%q] = %q\n",k ,v)
	}
}

Base2 是使用接口，使用结构体Engine实现了ServeHTTP的接口，接口内部使用Switch-case分别选择不同的路由进行处理。

 main.go

package main

import (
	"fmt"
	"log"
	"net/http"
)

type Engine struct {}

func (engine *Engine) ServeHTTP(w http.ResponseWriter, req *http.Request) {
	switch req.URL.Path {
	case "/":
		fmt.Fprintf(w,"URL.Path = %q \n",req.URL.Path)
	case "/hello":
		for k ,v := range req.Header {
			fmt.Fprintf(w, "Header[%q] = %q \n",k,v)
		}
	default:
		fmt.Fprintf(w,"404 NOT FOUND: %s \n", req.URL)
	}
}

func main() {
	engine := new (Engine)
	log.Fatal(http.ListenAndServe(":9999",engine))
}

Base3 搭建了gee框架的雏形，分别实现了main.go 和gee.go两个文件实现了基础的静态路由功能。

main.go

package main

import (
	"fmt"
	"net/http"

	"gee"
)

func main() {
	r := gee.New()
	r.GET("/",func(w http.ResponseWriter, req * http.Request){
		fmt.Fprintf(w,"URL.Path = %q \n", req.URL.Path)
	})

	r.GET("/hello",func(w http.ResponseWriter, req * http.Request){
		for k,v := range req.Header {
			fmt.Fprintf(w,"Headler[%q] = %q \n", k,v)
		}
		
	})

	r.Run(":9999")
}

gee.go

package gee

import (
	"fmt"
	"net/http"
)

type HandlerFunc  func(http.ResponseWriter, *http.Request)

type Engine struct {
	router map[string]HandlerFunc 
}

func New() *Engine {
	return &Engine{router: make(map[string]HandlerFunc)}
}

func (engine *Engine) addRoute(method string,pattern string,headler HandlerFunc){
	key := method + "-" + pattern
	engine.router[key] = headler
}

func (engine *Engine) GET(pattern string, handler HandlerFunc) {
	engine.addRoute("GET", pattern, handler)
}

func (engine *Engine) POST(pattern string, handler HandlerFunc) {
	engine.addRoute("POST", pattern, handler)
}

func (engine *Engine) Run(addr string) (err error) {
	return http.ListenAndServe(addr, engine)
}

func (engine *Engine) ServeHTTP(w http.ResponseWriter, req *http.Request) {
	key := req.Method + "-" + req.URL.Path
	if handler, ok := engine.router[key]; ok {
		handler(w, req)
	} else {
		fmt.Fprintf(w, "404 NOT FOUND: %s\n", req.URL)
	}
}

 在gee.go文件中以Engine结构体为基础实现了addRoute、GET、POST、Run、ServeHTTP的接口。

在Engine中，添加了一张路由映射表route，key 由请求方法和静态路由地址构成，GET和POST会将映射关系添加到map中 。ServeHTTP调用时去map中查找相应的关系，没有找到则返回404。