golang 下载大文件进度
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Table of Contents
使用io.Copy将下载的部分内容不断写入文件，重载io.Reader的Read函数，使用Read读取数据和大小，通过http的ContentLength获取total大小。
package goutil
import (
"io"
"net/http"
"os"
)
type ChunkReader struct {
io.Reader
Total int64
Offset int64
Progress func(offset, total int64)
}
func(r *ChunkReader)Read(b []byte)(n int, err error) {
n, err = r.Reader.Read(b)
r.Offset += int64(n)
if r.Progress != nil {
r.Progress(r.Offset, r.Total)
}
return
}
func DownloadFile(url, filepath string, progress func(offset, total int64)) error {
resp, err := http.Get(url)
if err != nil {
return err
}
defer resp.Body.Close()
f, err := os.Create(filepath)
if err != nil {
return err
}
defer f.Close()
r := &ChunkReader{
Reader: resp.Body,
Total: resp.ContentLength,
Progress: progress,
}
if _, err := io.Copy(f, r); err != nil {
return err
}
return nil
}
progress := func(offset, total int64) {
if total > 0 {
fmt.Printf("\r%.2f%%", float64(offset*100/total))
} else {
fmt.Printf("\r%d", offset)
}
}
url := "http://dldir1.qq.com/weixin/Windows/WeChat_3.2.1_update154.dat"
goutil.DownloadFile(url, "111.dat", progress)