golang随机数的问题,使用了网上所有的方法，都没有比较好的生成方式

我的代码： ``` package main import ( "fmt" "math/rand" //"runtime" "time" ) func main() { //runtime.GOMAXPROCS(1) fmt.Println("===rand.New(rand.NewSource(64))====") for i := 0; i < 20; i++ { r := rand.New(rand.NewSource(64)) fmt.Print(fmt.Sprint(r.Intn(5)) + "-") } fmt.Println("") fmt.Println("===rand.New(rand.NewSource(time.Now().UnixNano()))====") for i := 0; i < 20; i++ { r2 := rand.New(rand.NewSource(time.Now().UnixNano())) fmt.Print(fmt.Sprint(r2.Intn(5)) + "-") } fmt.Println("") fmt.Println("====rand.Seed(time.Now().UnixNano())===") for i := 0; i < 20; i++ { rand.Seed(time.Now().UnixNano()) fmt.Print(fmt.Sprint(rand.Intn(5)) + "-") } } ``` 输出的效果为： G:\goWorkspace\src>go run main.go ===rand.New(rand.NewSource(64))==== 3-3-3-3-3-3-3-3-3-3-3-3-3-3-3-3-3-3-3-3- ===rand.New(rand.NewSource(time.Now().UnixNano()))==== 1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1- ====rand.Seed(time.Now().UnixNano())=== 1-4-4-4-4-4-4-4-4-4-4-4-4-4-4-3-3-3-3-3- G:\goWorkspace\src>go run main.go ===rand.New(rand.NewSource(64))==== 3-3-3-3-3-3-3-3-3-3-3-3-3-3-3-3-3-3-3-3- ===rand.New(rand.NewSource(time.Now().UnixNano()))==== 1-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-4-4- ====rand.Seed(time.Now().UnixNano())=== 4-4-4-4-4-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2- G:\goWorkspace\src>go run main.go ===rand.New(rand.NewSource(64))==== 3-3-3-3-3-3-3-3-3-3-3-3-3-3-3-3-3-3-3-3- ===rand.New(rand.NewSource(time.Now().UnixNano()))==== 4-4-4-4-4-4-3-3-3-3-3-3-3-3-3-3-3-3-3-3- ====rand.Seed(time.Now().UnixNano())=== 1-1-1-1-1-1-1-2-2-2-2-2-2-2-2-2-2-2-2-2- >**环境：** >go版本 1.4 >操作系统：win8 64bit >有什么方法：让随机数更好的生成吗？