[Go]接收請求

ServeMux

ServeMux是一個包含映射的結構，映射會將URL映射到對應的伺服器。

DefaultServeMux

DefaultServeMux是net/HTTP中預設的多工器，是ServeMux的實例。多工器要根據URL的請求導向到不同的伺服器。DefaultServeMux是一個全域變數，也就是說專案裡的任何地方都能對它做修改，因此就可能會發生處理器衝突。所以比較建議自訂多工器。

自訂多工器

package main

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

func hi(w http.ResponseWriter, r *http.Request) {
	fmt.Fprintf(w, "Hi")
}

func main() {
	mux := http.NewServeMux()
	mux.HandleFunc("/", hi)

	server := &http.Server{
		Addr:    ":8081",
		Handler: mux,
	}

	if err := server.ListenAndServe(); err != nil {
		log.Fatal(err)
	}
}

HttpRouter

HttpRouter是一個高效能、可擴充的第三方套件。他尼補了net/HTTP預設路由不足的問題。

安裝

go get -u​ github.com/julienschmidt/httprouter

GET

package main

import (
	"github.com/julienschmidt/httprouter"
	"net/http"
)

func main() {
	router := httprouter.New()
	router.GET("/default", func(w http.ResponseWriter, r *http.Request, _ httprouter.Params) {
		w.Write([]byte("default get"))
	})
	
	http.ListenAndServe(":8083", router)
}

POST

package main

import (
	"github.com/julienschmidt/httprouter"
	"net/http"
)

func main() {
	router := httprouter.New()
	router.POST("/default", func(w http.ResponseWriter, r *http.Request, _ httprouter.Params) {
		w.Write([]byte("default post"))
	})
	
	http.ListenAndServe(":8083", router)
}

匹配方式

• 精確匹配：/user/:name

package main

import (
	"github.com/julienschmidt/httprouter"
	"net/http"
)

func main() {
	router := httprouter.New()
	
	//精确匹配
	router.GET("/user/name", func(w http.ResponseWriter, r *http.Request, p httprouter.Params) {
		w.Write([]byte("user name:" + p.ByName("name")))
	})
	
	http.ListenAndServe(":8083", router)
}

• 所有樣式：/user/*name

package main

import (
	"github.com/julienschmidt/httprouter"
	"net/http"
)

func main() {
	router := httprouter.New()
	//所有樣式
	router.GET("/user/*name", func(w http.ResponseWriter, r *http.Request, p httprouter.Params) {
		w.Write([]byte("user name:" + p.ByName("name")))
	})
	http.ListenAndServe(":8083", router)
}

處理二級域名

package main

import (
	"log"
	"net/http"
	"github.com/julienschmidt/httprouter"
)

type HostMap map[string]http.Handler

func (hs HostMap) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	//根據網域取得對應的Handler路由，然後呼叫處理（分發機制）
	if handler := hs[r.Host]; handler != nil {
		handler.ServeHTTP(w, r)
	} else {
		http.Error(w, "Forbidden", 403)
	}
}

func main() {
	userRouter := httprouter.New()
	userRouter.GET("/", func(w http.ResponseWriter, r *http.Request, p httprouter.Params) {
		w.Write([]byte("sub1"))
	})

	dataRouter := httprouter.New()
	dataRouter.GET("/", func(w http.ResponseWriter, r *http.Request, _ httprouter.Params) {
		w.Write([]byte("sub2"))
	})

	//分別用於處理不同的二級域名
	hs := make(HostMap)
	hs["sub1.localhost:8888"] = userRouter
	hs["sub2.localhost:8888"] = dataRouter

	log.Fatal(http.ListenAndServe(":8888", hs))
}

靜態檔案服務

package main

import (
	"log"
	"net/http"
	"github.com/julienschmidt/httprouter"
)

func main() {
	router := httprouter.New()
	
	router.ServeFiles("/static/*filepath", http.Dir("./files"))
	log.Fatal(http.ListenAndServe(":8086", router))
}

ServeFiles()第一個參數路徑必須是「/static/*filepath」；第二個參數為檔案目錄。

處理器

package main

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

type WelcomeHandler struct {
	Language string
}

func (h WelcomeHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	fmt.Fprintf(w, "%s", h.Language)
}

func main() {
	mux := http.NewServeMux()
	mux.Handle("/cn", WelcomeHandler{Language: "Go!"})
	
		server := &http.Server {
		Addr:   ":8082",
		Handler: mux,
	}

	if err := server.ListenAndServe(); err != nil {
		log.Fatal(err)
	}
}

處理器函數

package main

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

func hi(w http.ResponseWriter, r *http.Request) {
	fmt.Fprintf(w, "Go go!")
}

func main() {
	http.HandleFunc("/", hi)
	if err := http.ListenAndServe(":8081", nil); err != nil {
		log.Fatal(err)
	}
}