go_seckill/common/lib.go

package common

import (
	"bytes"
	"golang.org/x/text/encoding/simplifiedchinese"
	"golang.org/x/text/transform"
	"io/ioutil"
	"math/rand"
	"os"
	"os/exec"
	"runtime"
	"strconv"
	"time"
)

func Rand(min, max int) int {
	if min > max {
		panic("min: min cannot be greater than max")
	}
	if int31 := 1<<31 - 1; max > int31 {
		panic("max: max can not be greater than " + strconv.Itoa(int31))
	}
	if min == max {
		return min
	}
	r := rand.New(rand.NewSource(time.Now().UnixNano()))
	return r.Intn(max+1-min) + min
}

func GbkToUtf8(s []byte) ([]byte, error) {
	reader := transform.NewReader(bytes.NewReader(s), simplifiedchinese.GBK.NewDecoder())
	d, e := ioutil.ReadAll(reader)
	if e != nil {
		return nil, e
	}
	return d, nil
}

func Utf8ToGbk(s []byte) ([]byte, error) {
	reader := transform.NewReader(bytes.NewReader(s), simplifiedchinese.GBK.NewEncoder())
	d, e := ioutil.ReadAll(reader)
	if e != nil {
		return nil, e
	}
	return d, nil
}

func NewRandStr(length int) string {
	s := []string{
		"a", "b", "c", "d", "e", "f",
		"g", "h", "i", "j", "k", "l",
		"m", "n", "o", "p", "q", "r",
		"s", "t", "u", "v", "w", "x",
		"y", "z", "A", "B", "C", "D",
		"E", "F", "G", "H", "I", "J",
		"K", "L", "M", "N", "O", "P",
		"Q", "R", "S", "T", "U", "V",
		"W", "X", "Y", "Z",
	}
	str := ""
	for i := 1; i <= length; i++ {
		r := rand.New(rand.NewSource(time.Now().UnixNano()))
		str += s[r.Intn(len(s)-1)]
	}
	return str
}

func Substr(s string, start, end int) string {
	strRune := []rune(s)
	if start == -1 {
		return string(strRune[:end])
	}
	if end == -1 {
		return string(strRune[start:])
	}
	return string(strRune[start:end])
}

func IsDir(path string) bool {
	s, err := os.Stat(path)
	if err != nil {
		return false
	}
	return s.IsDir()
}

func Exists(path string) bool {
	_, err := os.Stat(path)
	if err != nil {
		if os.IsExist(err) {
			return true
		}
		return false
	}
	return true
}

func OpenImage(file string) {
	if runtime.GOOS == "windows" {
		cmd := exec.Command("cmd", "/k", "start", file)
		_ = cmd.Start()
	} else {
		if runtime.GOOS == "linux" {
			cmd := exec.Command("eog", file)
			_ = cmd.Start()
		} else {
			cmd := exec.Command("open", file)
			_ = cmd.Start()
		}
	}
}