golang 实现cdn

package main

import (
    "fmt"
    "io/ioutil"
    "net/http"
    "os"
    "strings"
)

func main() {
    // 静态文件服务器地址和缓存目录
    StaticServer := "http://server.static.com/"
    cacheDir := "./cache/"

    http.HandleFunc("/", func(writer http.ResponseWriter, request *http.Request) {
        // 解析客户端请求路径
        path := strings.TrimPrefix(request.URL.Path, "/")
        path = strings.Replace(path, "/", "-", -1)

        // 检查是否存在缓存文件
        cacheFile := cacheDir + path
        data, err := ioutil.ReadFile(cacheFile)
        if err == nil {
            writer.Write(data)
            return
        }

        // 如果缓存文件不存在，则向静态服务器请求文件
        fileUrl := StaticServer + request.URL.Path
        response, err := http.Get(fileUrl)
        if err != nil {
            fmt.Fprintf(os.Stderr, "http.Get() error: %v
", err)
            writer.WriteHeader(404)
            return
        }

        // 将静态文件复制到缓存目录，并返回给客户端
        defer response.Body.Close()
        data, err = ioutil.ReadAll(response.Body)
        if err != nil {
            fmt.Fprintf(os.Stderr, "ReadAll() error: %v
", err)
            writer.WriteHeader(500)
            return
        }

        ioutil.WriteFile(cacheFile, data, 0644)
        writer.Write(data)
    })

    http.ListenAndServe(":8080", nil)
}