1 package main
 2 
 3 import (
 4     "fmt"
 5     "io"
 6     "io/ioutil"
 7     "os"
 8 )
 9 
10 // 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
11 func CopyFile1(srcFile, destFile string) (int, error) {
12     file1, err := os.Open(srcFile)
13     if err != nil {
14         return 0, err
15     }
16     file2, err := os.OpenFile(destFile, os.O_WRONLY|os.O_CREATE, os.ModePerm)
17     if err != nil {
18         return 0, err
19     }
20     defer file1.Close()
21     defer file2.Close()
22 
23     //读写
24     bs := make([]byte, 1024, 1024)
25     n := -1 //读取的数据量
26     total := 0
27     for {
28         n, err = file1.Read(bs)
29         if err == io.EOF || n == 0 {
30             fmt.Println("拷贝完毕。。")
31             break
32         } else if err != nil {
33             fmt.Println("报错了。。")
34             return total, err
35         }
36         total += n
37         file2.Write(bs[:n])
38     }
39     return total, nil
40 }
41 
42 func CopyFile2(srcFile, destFile string) (int64, error) {
43     file1, err := os.Open(srcFile)
44     if err != nil {
45         return 0, err
46     }
47     file2, err := os.OpenFile(destFile, os.O_WRONLY|os.O_CREATE, os.ModePerm)
48     if err != nil {
49         return 0, err
50     }
51     defer file1.Close()
52     defer file2.Close()
53     return io.Copy(file2, file1)
54 }
55 
56 func CopyFile3(srcFile, destFile string) (int, error) {
57     bs, err := ioutil.ReadFile(srcFile)
58     if err != nil {
59         return 0, err
60     }
61     err = ioutil.WriteFile(destFile, bs, 0777)
62     if err != nil {
63         return 0, err
64     }
65     return len(bs), nil
66 }
67 
68 func main() {
69     /*
70         拷贝文件：
71     */
72 
73     srcFile := "D:\\Go\\web2\\aa.txt"
74     destFile := "bb.txt"
75     // 覆盖 destFile 内容 size = srcFile 的部分
76     // total, err := CopyFile1(srcFile, destFile)
77     // 覆盖 destFile 内容 size = srcFile 的部分
78     // total, err := CopyFile2(srcFile, destFile)
79     // 完全重写
80     total, err := CopyFile3(srcFile, destFile)
81     fmt.Println(total, err)
82 }