92_Go基础_1_60 拷贝文件

package main

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

// 该函数：用于通过io操作实现文件的拷贝，返回值是拷贝的总数量(字节),错误
func CopyFile1(srcFile, destFile string) (int, error) {
    file1, err := os.Open(srcFile)
    if err != nil {
        return 0, err
    }
    file2, err := os.OpenFile(destFile, os.O_WRONLY|os.O_CREATE, os.ModePerm)
    if err != nil {
        return 0, err
    }
    defer file1.Close()
    defer file2.Close()

    //读写
    bs := make([]byte, 1024, 1024)
    n := -1 //读取的数据量
    total := 0
    for {
        n, err = file1.Read(bs)
        if err == io.EOF || n == 0 {
            fmt.Println("拷贝完毕。。")
            break
        } else if err != nil {
            fmt.Println("报错了。。")
            return total, err
        }
        total += n
        file2.Write(bs[:n])
    }
    return total, nil
}

func CopyFile2(srcFile, destFile string) (int64, error) {
    file1, err := os.Open(srcFile)
    if err != nil {
        return 0, err
    }
    file2, err := os.OpenFile(destFile, os.O_WRONLY|os.O_CREATE, os.ModePerm)
    if err != nil {
        return 0, err
    }
    defer file1.Close()
    defer file2.Close()
    return io.Copy(file2, file1)
}

func CopyFile3(srcFile, destFile string) (int, error) {
    bs, err := ioutil.ReadFile(srcFile)
    if err != nil {
        return 0, err
    }
    err = ioutil.WriteFile(destFile, bs, 0777)
    if err != nil {
        return 0, err
    }
    return len(bs), nil
}

func main() {
    /*
        拷贝文件：
    */

    srcFile := "D:\\Go\\web2\\aa.txt"
    destFile := "bb.txt"
    // 覆盖 destFile 内容 size = srcFile 的部分
    // total, err := CopyFile1(srcFile, destFile)
    // 覆盖 destFile 内容 size = srcFile 的部分
    // total, err := CopyFile2(srcFile, destFile)
    // 完全重写
    total, err := CopyFile3(srcFile, destFile)
    fmt.Println(total, err)
}