golang 的string与[]byte转换方式

type SliceHeader struct {
    Data uintptr
    Len  int
    Cap  int
}
type StringHeader struct {
    Data uintptr
    Len  int
}

//return GoString's buffer slice(enable modify string)
func StringBytes(s string) Bytes {
    return *(*Bytes)(unsafe.Pointer(&s))
}
// convert b to string without copy
func BytesString(b []byte) String {
    return *(*String)(unsafe.Pointer(&b))
}
// returns &s[0], which is not allowed in go
func StringPointer(s string) unsafe.Pointer {
    p := (*reflect.StringHeader)(unsafe.Pointer(&s))
    return unsafe.Pointer(p.Data)
}
// returns &b[0], which is not allowed in go
func BytesPointer(b []byte) unsafe.Pointer {
    p := (*reflect.SliceHeader)(unsafe.Pointer(&b))
    return unsafe.Pointer(p.Data)
}

func TestPointer(t *testing.T) {
    s := []string{
        "",
        "",
        "hello",
        "hello",
        fmt.Sprintf(""),
        fmt.Sprintf(""),
        fmt.Sprintf("hello"),
        fmt.Sprintf("hello"),
    }
    fmt.Println("String to bytes:")
    for i, v := range s {
        b := unsafe.StringBytes(v)
        b2 := []byte(v)
        if b.Writeable() {
            b[0] = 'x'
        }
        fmt.Printf("%d\ts=%5s\tptr(v)=%-12v\tptr(StringBytes(v)=%-12v\tptr([]byte(v)=%-12v\n",
            i, v, unsafe.StringPointer(v), b.Pointer(), unsafe.BytesPointer(b2))
    }
    b := [][]byte{
        []byte{},
        []byte{'h', 'e', 'l', 'l', 'o'},
    }
    fmt.Println("Bytes to string:")
    for i, v := range b {
        s1 := unsafe.BytesString(v)
        s2 := string(v)
        fmt.Printf("%d\ts=%5s\tptr(v)=%-12v\tptr(StringBytes(v)=%-12v\tptr(string(v)=%-12v\n",
            i, s1, unsafe.BytesPointer(v), s1.Pointer(), unsafe.StringPointer(s2))
    }
}
const N = 3000000
func Benchmark_NORMal(b *testing.B) {
    for i := 1; i < N; i++ {
        s := fmt.Sprintf("12345678901234567890123456789012345678901234567890")
        bb := []byte(s)
        bb[0] = 'x'
        s = string(bb)
        s = s
    }
}
func Benchmark_Direct(b *testing.B) {
    for i := 1; i < N; i++ {
        s := fmt.Sprintf("12345678901234567890123456789012345678901234567890")
        bb := unsafe.StringBytes(s)
        bb[0] = 'x'
        s = s
    }
}
//test result
//String to bytes:
//0 s=      ptr(v)=0x51bd70     ptr(StringBytes(v)=0x51bd70     ptr([]byte(v)=0xc042021c58
//1 s=      ptr(v)=0x51bd70     ptr(StringBytes(v)=0x51bd70     ptr([]byte(v)=0xc042021c58
//2 s=hello ptr(v)=0x51c2fa     ptr(StringBytes(v)=0x51c2fa     ptr([]byte(v)=0xc042021c58
//3 s=hello ptr(v)=0x51c2fa     ptr(StringBytes(v)=0x51c2fa     ptr([]byte(v)=0xc042021c58
//4 s=      ptr(v)=<nil>        ptr(StringBytes(v)=<nil>        ptr([]byte(v)=0xc042021c58
//5 s=      ptr(v)=<nil>        ptr(StringBytes(v)=<nil>        ptr([]byte(v)=0xc042021c58
//6 s=xello ptr(v)=0xc0420444b5 ptr(StringBytes(v)=0xc0420444b5 ptr([]byte(v)=0xc042021c58
//7 s=xello ptr(v)=0xc0420444ba ptr(StringBytes(v)=0xc0420444ba ptr([]byte(v)=0xc042021c58
//Bytes to string:
//0 s=      ptr(v)=0x5c38b8     ptr(StringBytes(v)=0x5c38b8     ptr(string(v)=<nil>
//1 s=hello ptr(v)=0xc0420445e0 ptr(StringBytes(v)=0xc0420445e0 ptr(string(v)=0xc042021c38
//Benchmark_Normal-4    1000000000           0.87 ns/op
//Benchmark_Direct-4    2000000000           0.24 ns/op

Res := string(bytes)

func main()  {
 var s = []byte("我永远喜欢藤原千花.jpg")
 Res := *(*string)(unsafe.Pointer(&s))
 fmt.Println(Res)
}

type SliceHeader struct {
 Data uintptr
 Len  int
 Cap  int
  } 
type StringHeader struct {
 Data uintptr
 Len  int
  }