golang 大文件分割与合并

package main

import (
   "fmt"
   "io/ioutil"
   "math"
   "os"
   "strconv"
)

const chunkSize = 1 << (10 * 2)

func main() {
   fileInfo, err := os.Stat("cbd.mp4")
   if err != nil {
      panic(err)
   }

   num := math.Ceil(float64(fileInfo.Size()) / chunkSize)

   fi, err := os.OpenFile("cbd.mp4", os.O_RDONLY, os.ModePerm)
   if err != nil {
      fmt.Println(err)
      return
   }
   b := make([]byte, chunkSize)
   var i int64 = 1
   for ; i <= int64(num); i++ {
      fi.Seek((i-1)*chunkSize, 0)
      if len(b) > int(fileInfo.Size()-(i-1)*chunkSize) {
         b = make([]byte, fileInfo.Size()-(i-1)*chunkSize)
      }
      fi.Read(b)

      f, err := os.OpenFile("./"+strconv.Itoa(int(i))+".db", os.O_CREATE|os.O_WRONLY, os.ModePerm)
      if err != nil {
         panic(err)
      }
      f.Write(b)
      f.Close()
   }
   fi.Close()

   fii, err := os.OpenFile("all.mp4", os.O_CREATE|os.O_WRONLY|os.O_APPEND, os.ModePerm)
   if err != nil {
      panic(err)
      return
   }
   for i := 1; i <= int(num); i++ {
      f, err := os.OpenFile("./"+strconv.Itoa(int(i))+".db", os.O_RDONLY, os.ModePerm)
      if err != nil {
         fmt.Println(err)
         return
      }
      b, err := ioutil.ReadAll(f)
      if err != nil {
         fmt.Println(err)
         return
      }
      fii.Write(b)
      f.Close()
   }
}

转载于:https://my.oschina.net/wgc2010/blog/2873082