utils.go

package main

import (
    "io"
    "time"
    "math/rand"
    "fmt"
    "crypto/sha1"
    "encoding/json"
    "log"
    "os"
)

func sumSha1(str string) string {
    t := sha1.New();
    io.WriteString(t, str);
    return fmt.Sprintf("%x",t.Sum(nil));
}

// now to sql DATETIME string
// refer to http://ichon.me/post/998.html
func nowToDateTime() string {
    return time.Now().Format("2006-01-02 15:04:05")
}

func makeJson(v interface{}) string {
    bin, err := json.Marshal(v)
    if err != nil {
        log.Print(err)
        return "Marshal json fail!"
    }
    return string(bin)
}

func isExist(filename string) bool {
    _, err := os.Stat(filename)
    return err == nil || os.IsExist(err)
}

// return [start, end)
func randInRange(start int, end int) int {
    r := rand.New(rand.NewSource(time.Now().UnixNano()))
    num := r.Intn(end)
    return num + start
}