golang实现多协程下载文件(支持断点续传)

我就是我 2022-09-16 06:38 190阅读 0赞

# 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")
    }