Go 大文件下载并且显示进度

package main

import (
    "fmt"
    "io"
    "log"
    "net/http"
    "os"
    "sync"
)

type Downloader struct {
    io.Reader
    Total   int64
    Current int64
}

func (d *Downloader) Read(p []byte) (n int, err error) {
    n, err = d.Reader.Read(p)
    d.Current += int64(n)
    fmt.Printf("\r正在下载，下载进度：%.2f%%", float64(d.Current*10000/d.Total)/100)
    if d.Current == d.Total {
        fmt.Printf("\r下载完成，下载进度：%.2f%%", float64(d.Current*10000/d.Total)/100)
    }
    return
}

func downloadFile(url, filePath string) {
    defer wg.Done()
    resp, err := http.Get(url)
    if err != nil {
        log.Fatalln(err)
    }
    defer func() {
        _ = resp.Body.Close()
    }()
    file, err := os.Create(filePath)
    defer func() {
        _ = file.Close()
    }()
    downloader := &Downloader{
        Reader: resp.Body,
        Total:  resp.ContentLength,
    }
    if _, err := io.Copy(file, downloader); err != nil {
        log.Fatalln(err)
    }
}

var wg sync.WaitGroup

func main() {
    task := make(map[string]string)
    task["https://dl.softmgr.qq.com/original/game/WeGameSetup3.32.4.6183_gjwegame_0_0.exe"] = "d:/wegame.exe"
    for k, v := range task {
        wg.Add(1)
        downloadFile(k, v)
    }
    wg.Wait()
}