下面是GoLang 计算小文件或大文件 md5 值的例子
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package main
import (
"crypto/md5"
"fmt"
"io"
"os"
)
func main() {
testFile := "/path/to/file"
file, err := os.Open(testFile)
if err != nil {
fmt.Println(err)
return
}
md5h := md5.New()
io.Copy(md5h, file)
fmt.Printf("%x", md5h.Sum([]byte(""))) //md5
}
如果是大文件，可以分块计算，参见下面例子：
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package main
import (
"crypto/md5"
"fmt"
"io"
"math"
"os"
)
const filechunk = 8192 // we settle for 8KB
func main() {
file, err := os.Open("utf8.txt")
if err != nil {
panic(err.Error())
}
defer file.Close()
// calculate the file size
info, _ := file.Stat()
filesize := info.Size()
blocks := uint64(math.Ceil(float64(filesize) / float64(filechunk)))
hash := md5.New()
for i := uint64(0); i < blocks; i++ {
blocksize := int(math.Min(filechunk, float64(filesize-int64(i*filechunk))))
buf := make([]byte, blocksize)
file.Read(buf)
io.WriteString(hash, string(buf)) // append into the hash
}
fmt.Printf("%s checksum is %x\n", file.Name(), hash.Sum(nil))
}
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