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？