golang实现多协程下载文件(支持断点续传)

引言

写这篇文章主要是周末休息太无聊,看了看别人代码,发现基本上要么是多协程下载文件要么就只有单协程的断点续传,所以就试了试有进度条的多协程下载文件(支持断点续传)

package main

import (
"fmt"
"io"
"os"
"regexp"
"strconv"
"sync"

"github.com/qianlnk/pgbar"
)

/**
* 需求:
1. 多协程下载文件
2.断点续连
**/
func main() {
//获取要下载文件
DownloadFileName := "./123.zip"
//copy的文件
copyFileName := "./test.zip"
storgeFileName := "./current.txt"
//打开文件
sfile, err := os.Open(DownloadFileName)
if err != nil {
 panic(err)
}
defer sfile.Close()
//获取文件大小
info, _ := sfile.Stat()
downloadSize := info.Size()
var scount int64 = 1
if downloadSize％5 == 0 {
 scount *= 5
} else {
 scount *= 10
}
//分给每个协程的大小
si := downloadSize / scount
fmt.Printf("文件总大小：％v, 分片数：％v,每个分片大小：％v\n", downloadSize, scount, si)
//open copy file
copyFile, err := os.OpenFile(copyFileName, os.O_CREATE|os.O_WRONLY, os.ModePerm)
if err != nil {
 panic(err)
}
storgeFile, err := os.OpenFile(storgeFileName, os.O_CREATE|os.O_RDWR, os.ModePerm)
if err != nil {
 panic(err)
}
defer copyFile.Close()

var currentIndex int64 = 0
wg := sync.WaitGroup{}
fmt.Println("协程进度条")
pgb := pgbar.New("")
for ; currentIndex < scount; currentIndex++ {
 wg.Add(1)
 go func(current int64) {
  p := pgb.NewBar(fmt.Sprint((current+1))+"st", int(si))
  // p.SetSpeedSection(900, 100)
  b := make([]byte, 1024)
  bs := make([]byte, 16)
  currentIndex, _ := storgeFile.ReadAt(bs, current*16)
  //取出所有整数
  reg := regexp.MustCompile(`\d+`)
  countStr := reg.FindString(string(bs[:currentIndex]))
  total, _ := strconv.ParseInt(countStr, 10, 0)
  progressBar := 1
  for {
   if total >= si {
    wg.Done()
    break
   }
   //从指定位置开始读
   n, err := sfile.ReadAt(b, current*si+total)
   if err == io.EOF {
    wg.Done()
    break
   }
   //从指定位置开始写
   copyFile.WriteAt(b, current*si+total)
   storgeFile.WriteAt([]byte(strconv.FormatInt(total, 10)+" "), current*16)
   total += int64(n)
   if total >= si/10*int64(progressBar) {
    progressBar += 1
    p.Add(int(si / 10))
   }

}

}(currentIndex)
}
wg.Wait()
storgeFile.Close()
os.Remove(storgeFileName)
fmt.Println("下载完成")
}

来源：https://blog.csdn.net/a1309525802/article/details/120814564