Golang 获取文件md5校验的方法以及效率对比

package main
import (
 "crypto/md5"
 "flag"
 "fmt"
 "io"
 "io/ioutil"
 "os"
)
var which = flag.Bool("which", true, "")
var path = flag.String("path", "", "")
var cnt = flag.Int("cnt", 100, "")
func aaa() {
 f, err := os.Open(*path)
 if err != nil {
  fmt.Println("Open", err)
  return
 }
 defer f.Close()
 body, err := ioutil.ReadAll(f)
 if err != nil {
  fmt.Println("ReadAll", err)
  return
 }
 md5.Sum(body)
 //fmt.Printf("%x\n", md5.Sum(body))
}
func bbb() {
 f, err := os.Open(*path)
 if err != nil {
  fmt.Println("Open", err)
  return
 }
 defer f.Close()
 md5hash := md5.New()
 if _, err := io.Copy(md5hash, f); err != nil {
  fmt.Println("Copy", err)
  return
 }
 md5hash.Sum(nil)
 //fmt.Printf("%x\n", md5hash.Sum(nil))
}
func main() {
 flag.Parse()
 for i := 0; i < *cnt; i++ {
  if *which {
   aaa()
  } else {
   bbb()
  }
 }
}

md5 -- calculate a message-digest fingerprint (checksum) for a file
md5 [-pqrtx] [-s string] [file ...]

banjakukutekiiMac:shell panshiqu$ ls -an | grep by
-rw-r--r--   1 501  20   7285957 11 17 16:14 by.out
banjakukutekiiMac:shell panshiqu$ cp by.out by2.out
banjakukutekiiMac:shell panshiqu$ cat by.out >> by2.out
banjakukutekiiMac:shell panshiqu$ ls -an | grep by
-rw-r--r--   1 501  20   7285957 11 17 16:14 by.out
-rw-r--r--   1 501  20  14571914 11 17 17:03 by2.out

banjakukutekiiMac:shell panshiqu$ time ./gomd5 -cnt=1 -which=true -path="by.out"
real 0m0.027s
user 0m0.017s
sys 0m0.012s
banjakukutekiiMac:shell panshiqu$ time ./gomd5 -cnt=1 -which=true -path="by2.out"
real 0m0.048s
user 0m0.033s
sys 0m0.018s
banjakukutekiiMac:shell panshiqu$ time ./gomd5 -cnt=1 -which=false -path="by.out"
real 0m0.018s
user 0m0.012s
sys 0m0.004s
banjakukutekiiMac:shell panshiqu$ time ./gomd5 -cnt=1 -which=false -path="by2.out"
real 0m0.031s
user 0m0.024s
sys 0m0.005s
banjakukutekiiMac:shell panshiqu$ time md5 by.out
MD5 (by.out) = 9d79e19a00cef1ae1bb6518ca4adf9de
real 0m0.023s
user 0m0.019s
sys 0m0.006s
banjakukutekiiMac:shell panshiqu$ time md5 by2.out
MD5 (by2.out) = 0a029a460a20e8dcb00d032d6fab74c6
real 0m0.042s
user 0m0.037s
sys 0m0.009s

 
const hextable = "0123456789abcdef" 
//作者: pengpengzhou
func FastMD5(str string) string {
	src := md5.Sum([]byte(str))
	var dst = make([]byte, 32)
	j := 0
	for _, v := range src {
		dst[j] = hextable[v>>4]
		dst[j+1] = hextable[v&0x0f]
		j += 2
	}
	return string(dst)
}

goos: linux
goarch: amd64
pkg: example
BenchmarkFastMD5-4       5564898               205 ns/op
BenchmarkV1-4            3461698               379 ns/op
BenchmarkV2-4            2277235               516 ns/op
BenchmarkV3-4            2158122               527 ns/op
PASS
ok      example 6.440s

package main 
import (
	"crypto/md5"
	"encoding/hex"
	"fmt"
	"io"
)
 
const hextable = "0123456789abcdef"
 
func FastMD5(str string) string {
	src := md5.Sum([]byte(str))
	var dst = make([]byte, 32)
	j := 0
	for _, v := range src {
		dst[j] = hextable[v>>4]
		dst[j+1] = hextable[v&0x0f]
		j += 2
	}
	return string(dst)
}
 
func md5V1(str string) string {
	h := md5.New()
	h.Write([]byte(str))
	return hex.EncodeToString(h.Sum(nil))
}
 
func md5V2(str string) string {
	data := []byte(str)
	has := md5.Sum(data)
	md5str := fmt.Sprintf("%x", has)
	return md5str
}
 
func md5V3(str string) string {
	w := md5.New()
	io.WriteString(w, str)
	md5str := fmt.Sprintf("%x", w.Sum(nil))
	return md5str
}
 
func main() {
	str := "中文"
	fmt.Println(FastMD5(str))
	fmt.Println(md5V1(str))
	fmt.Println(md5V2(str))
	fmt.Println(md5V3(str))
}

package main 
import (
	"testing"
)
 
var str = "golang中文教程"
 
func BenchmarkFastMD5(b *testing.B) {
	for i := 0; i < b.N; i++ {
		FastMD5(str)
	}
}
 
func BenchmarkV1(b *testing.B) {
	for i := 0; i < b.N; i++ {
		md5V1(str)
	}
}
 
func BenchmarkV2(b *testing.B) {
	for i := 0; i < b.N; i++ {
		md5V2(str)
	}
}
 
func BenchmarkV3(b *testing.B) {
	for i := 0; i < b.N; i++ {
		md5V3(str)
	}
}