package main

import (

    "fmt"

    "io"

    "os"

    "path/filepath"

    "strconv"

)

var BUFFERSIZE int64

func Copy1(src, dst string, BUFFERSIZE int64) error {

    sourceFileStat, err := os.Stat(src)

    if err != nil {

        return err

    }

    if !sourceFileStat.Mode().IsRegular() {

        return fmt.Errorf("%s is not a regular file", src)

    }

    source, err := os.Open(src)

    if err != nil {

        return err

    }

    defer source.Close()

    _, err = os.Stat(dst)

    if err == nil {

        return fmt.Errorf("file %s already exists", dst)

    }

    destination, err := os.Create(dst)

    if err != nil {

        return err

    }

    defer destination.Close()

    if err != nil {

        panic(err)

    }

    buf := make([]byte, BUFFERSIZE)

    for {

        n, err := source.Read(buf)

        if err != nil && err != io.EOF {

            return err

        }

        if n == 0 {

            break

        }

        if _, err := destination.Write(buf[:n]); err != nil {

            return err

        }

    }

    return err

}

func Copy(src, dst string) (int64, error) {

    sourceFileStat, err := os.Stat(src)

    if err != nil {

        return 0, err

    }

    if !sourceFileStat.Mode().IsRegular() {

        return 0, fmt.Errorf("%s is not a regular file", src)

    }

    source, err := os.Open(src)

    if err != nil {

            return 0, err

    }

    defer source.Close()

    destination, err := os.Create(dst)

    if err != nil {

        return 0, err

    }

    defer destination.Close()

    nBytes, err := io.Copy(destination, source)

    return nBytes, err

}

func main() {

    if len(os.Args) != 4 {

        fmt.Printf("usage: %s source destination BUFFERSIZE\n",

            filepath.Base(os.Args[0]))

        os.Exit(1)

    }

    source := os.Args[1]

    destination := os.Args[2]

    BUFFERSIZE, _ = strconv.ParseInt(os.Args[3], 10, 64)

    fmt.Printf("Copying %s to %s\n", source, destination)

    err := Copy1(source, destination, BUFFERSIZE)

    if err != nil {

        fmt.Printf("File copying failed: %q\n", err)

    }

}


作者：holdtom
链接：https://www.imooc.com/article/271446
来源：慕课网