Golang FileServer 检查进度

Question

我已经使用 GoLang 创建了一个简单的 FileServer

package main

import (
    "log"
    "net/http"
)

func loggingHandler(h http.Handler) http.Handler {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        log.Println(r.Method, r.RemoteAddr,r.URL.Path)
        h.ServeHTTP(w, r)
    })
}

func main() {
    http.ListenAndServe(":8080", loggingHandler(http.FileServer(http.Dir("/directory/subdir/"))))
}

现在我正在寻找一种方法来检查主机是否正确下载了文件，或者监控已经下载了多少字节。 不幸的是，我无法在互联网上找到任何提示，甚至无法找到。 有没有人遇到过类似的问题？是否可以验证从服务器下载文件的正确性？

Answer 1

您可以为FileSystem 的实现提供FileServer 的进度计数器。

例子：

package main

import (
    "net/http"
)

type fileWithProgress struct {
    http.File
    size         int64
    downloaded   int64
    lastReported int64
    name         string
    client       string
}

func (f *fileWithProgress) Read(p []byte) (n int, err error) {
    n, err = f.File.Read(p)
    f.downloaded += int64(n)
    f.lastReported += int64(n)
    if f.lastReported > 1_000_000 { // report every 1e6 bytes
        println("client:", f.client, "file:", f.name, "downloaded:", f.downloaded*100/f.size, "%")
        f.lastReported = 0
    }
    return n, err
}

func (f *fileWithProgress) Seek(offset int64, whence int) (int64, error) {
    f.downloaded = 0 // reset content detection read if no content-type specified
    return f.File.Seek(offset, whence)
}

func (f *fileWithProgress) Close() error {
    println("client:", f.client, "file:", f.name, "done", f.downloaded, "of", f.size, "bytes")
    return f.File.Close()
}

type dirWithProgress struct {
    http.FileSystem
    client string
}

func (d *dirWithProgress) Open(name string) (http.File, error) {
    println("open:", name, "for the client:", d.client)
    f, err := d.FileSystem.Open(name)
    if err != nil {
        return nil, err
    }
    st, err := f.Stat()
    if err != nil {
        return nil, err
    }
    return &fileWithProgress{File: f, size: st.Size(), name: st.Name(), client: d.client}, nil
}

func fileServer(fs http.FileSystem) http.Handler {
    f := func(w http.ResponseWriter, r *http.Request) {
        progressDir := dirWithProgress{FileSystem: fs, client: r.RemoteAddr}
        http.FileServer(&progressDir).ServeHTTP(w, r)
    }
    return http.HandlerFunc(f)
}

func main() {
    dir := http.Dir(".")
    fs := fileServer(dir)
    http.Handle("/", fs)
    http.ListenAndServe("127.0.0.1:8080", nil)
}