封送至JSON时，如何强制将[[8] byte]编码为十六进制

By default byte slices are marshalled as Base64 strings and byte arrays are converted as is:

func main() {
    type Foo struct {
        ByteSlice []byte
        ByteArray [6]byte
    }

    foo := Foo {
        ByteSlice: []byte{0, 0, 0, 1, 2, 3},
        ByteArray: [6]byte{0, 0, 0, 1, 2, 3},
    }
    text, _ := json.Marshal(foo)
    fmt.Printf("%s", text)
}

Output:

{"ByteSlice":"AAAAAQID","ByteArray":[0,0,0,1,2,3]}

Is there a way to use hex string conversion for byte slices?

Is there a way to use hex string conversion for byte slices?

No there is not.

You have to encode it yourself. Either into a new struct with a string field or by writing your own UnmarshalJSON method as described in package json's doc.

You could customize JSON serialization if you define a custom type. I've substitute []byte for instance:

Output:

{"ByteSlice":"000000010203","ByteArray":[0,0,0,1,2,3]}

Code:

package main

import (
    "encoding/hex"
    "encoding/json"
    "fmt"
)

type MyByteSlice []byte

func (m MyByteSlice) MarshalJSON() ([]byte, error) {
    return json.Marshal(hex.EncodeToString(m))
}

func main() {
    type Foo struct {
        ByteSlice MyByteSlice
        ByteArray [6]byte
    }

    foo := Foo {
        ByteSlice: []byte{0, 0, 0, 1, 2, 3},
        ByteArray: [6]byte{0, 0, 0, 1, 2, 3},
    }

    text, _ := json.Marshal(foo)
    fmt.Printf("%s
", text)
}