为什么在解组JSON时字符串和[]字节的处理方式不同？(Why are string and []bytes treated differently when unmarshaling JSON?)

 我从阅读文档中得到的理解是， string本质上是一个不可变的[]byte ，并且可以轻松地在两者之间进行转换。 
 
 然而，当从JSON解组时，这似乎并不正确。 采用以下示例程序： 
 
package main

import (
    "encoding/json"
    "fmt"
)

type STHRaw struct {
    Hash []byte `json:"hash"`
}

type STHString struct {
    Hash string `json:"hash"`
}

func main() {
    bytes := []byte(`{"hash": "nuyHN9wx4lZL2L3Ir3dhZpmggTQEIHEZcC3DUNCtQsk="}`)

    stringHead := new(STHString)
    if err := json.Unmarshal(bytes, &stringHead); err != nil {
        return
    }

    rawHead := new(STHRaw)
    if err := json.Unmarshal(bytes, &rawHead); err != nil {
        return
    }

    fmt.Printf("String:\t\t%x\n", stringHead.Hash)
    fmt.Printf("Raw:\t\t%x\n", rawHead.Hash)
    fmt.Printf("Raw to string:\t%x\n", string(rawHead.Hash[:]))
}
 
 这给出了以下输出： 
 
String:         6e7579484e397778346c5a4c324c3349723364685a706d67675451454948455a63433344554e437451736b3d
Raw:            9eec8737dc31e2564bd8bdc8af77616699a0813404207119702dc350d0ad42c9
Raw to string:  9eec8737dc31e2564bd8bdc8af77616699a0813404207119702dc350d0ad42c9 
 
 相反，我希望每次都能获得相同的价值。 
 
 有什么不同？ 

My understanding from reading the documentation was that string is essentially an immutable []byte and that one can easily convert between the two.
 
However when unmarshaling from JSON this doesn't seem to be true. Take the following example program:
 
package main

import (
    "encoding/json"
    "fmt"
)

type STHRaw struct {
    Hash []byte `json:"hash"`
}

type STHString struct {
    Hash string `json:"hash"`
}

func main() {
    bytes := []byte(`{"hash": "nuyHN9wx4lZL2L3Ir3dhZpmggTQEIHEZcC3DUNCtQsk="}`)

    stringHead := new(STHString)
    if err := json.Unmarshal(bytes, &stringHead); err != nil {
        return
    }

    rawHead := new(STHRaw)
    if err := json.Unmarshal(bytes, &rawHead); err != nil {
        return
    }

    fmt.Printf("String:\t\t%x\n", stringHead.Hash)
    fmt.Printf("Raw:\t\t%x\n", rawHead.Hash)
    fmt.Printf("Raw to string:\t%x\n", string(rawHead.Hash[:]))
}
 
This gives the following output:
 
String:         6e7579484e397778346c5a4c324c3349723364685a706d67675451454948455a63433344554e437451736b3d
Raw:            9eec8737dc31e2564bd8bdc8af77616699a0813404207119702dc350d0ad42c9
Raw to string:  9eec8737dc31e2564bd8bdc8af77616699a0813404207119702dc350d0ad42c9 
 
Instead I would have expected to receive the same value each time.
 
What is the difference?

原文：