如何编组一个byte / uint8数组作为JSON数组? [英] How to marshal a byte/uint8 array as json array in Go?
问题描述
我有一个带有 [] uint8
成员的结构体,我用 json.Marshal
。麻烦的是,它将 uint8
s解释为 char
s,并输出一个字符串而不是数组。
如果它是 [] int
,我可以得到它的工作,但我不想如果我可以避免它分配和复制的项目。我可以吗?
根据 docs , [] byte
将被编码为Base64字符串。
数组和切片值编码为JSON数组,除了[]字节编码为base64编码的字符串,且无切片编码作为空的JSON对象。
所以我认为你可能需要让你的结构实现 Marshaler 界面通过实现您自己的 MarshalJSON
方法这使得在你的 [] uint8
中有一个更理想的JSON数组编码。
以下例子:
导入fmt
导入编码/ json
导入字符串
类型测试结构{
名称字符串
Array [] uint8
}
func(t * Te st)MarshalJSON()([] byte,error){
var array string
if t.Array == nil {
array =null
} else {
array = strings.Join(strings.Fields(fmt.Sprintf(%d,t.Array)),,)
}
jsonResult:= fmt.Sprintf(`{ Name:%q,Array:%s}`,t.Name,array)
return [] byte(jsonResult),nil
}
func main ){
t:=& Test {Go,[] uint8 {'h','e','l','l','o'}}
m, err:= json.Marshal(t)
if err!= nil {
fmt.Println(err)
}
fmt.Printf(%s,m)/ / {Name:Go,Array:[104,101,108,108,111]}
}
http://play.golang.org/p/Tip59Z9gqs
或者一个更好的方法是创建一个新类型,它具有 [] uint8
作为其基础类型,使该类型为 Marshaler
,并在您的结构中使用该类型
导入fmt
导入编码/ json
导入字符串
类型JSONableSlice [] uint8
func(u JSONableSlice)MarshalJSON()([] byte,error){
var结果字符串
if u == nil {
result =null
} else {
result = strings.Join(strings.Fields(fmt.Sprintf(%d,u)),,)
}
return [] byte(result),nil
}
类型测试结构{
名称字符串
数组JSONableSlice
}
func main(){
t:=& Test {Go,[] uint8 {'h','e','l','l','o '}}
$ bm,err:= json.Marshal(t)
if err!= nil {
fmt.Println(err)
}
fmt.Printf(%s,m)// {Name:Go,Array:[104,101,108,108,111]}
}
http://play.golang.org/p / 6aURXw8P5d
I've got a struct with a []uint8
member and I'm writing it with json.Marshal
. Trouble is, it's interpreting the uint8
s as char
s and it outputs a string rather than an array of numbers.
I can get this to work if it's a []int
, but I don't want to have to allocate and copy over the items if I can avoid it. Can I?
According to the docs, a []byte
will be encoded as a Base64 string.
"Array and slice values encode as JSON arrays, except that []byte encodes as a base64-encoded string, and a nil slice encodes as the null JSON object."
So I think that you may need to make your struct implement the Marshaler interface by implementing your own MarshalJSON
method that makes a more desirable JSON array encoding out of your []uint8
.
Take this example:
import "fmt"
import "encoding/json"
import "strings"
type Test struct {
Name string
Array []uint8
}
func (t *Test) MarshalJSON() ([]byte, error) {
var array string
if t.Array == nil {
array = "null"
} else {
array = strings.Join(strings.Fields(fmt.Sprintf("%d", t.Array)), ",")
}
jsonResult := fmt.Sprintf(`{"Name":%q,"Array":%s}`, t.Name, array)
return []byte(jsonResult), nil
}
func main() {
t := &Test{"Go", []uint8{'h', 'e', 'l', 'l', 'o'}}
m, err := json.Marshal(t)
if err != nil {
fmt.Println(err)
}
fmt.Printf("%s", m) // {"Name":"Go","Array":[104,101,108,108,111]}
}
http://play.golang.org/p/Tip59Z9gqs
Or maybe a better idea would be to make a new type that has []uint8
as its underlying type, make that type a Marshaler
, and use that type in your struct.
import "fmt"
import "encoding/json"
import "strings"
type JSONableSlice []uint8
func (u JSONableSlice) MarshalJSON() ([]byte, error) {
var result string
if u == nil {
result = "null"
} else {
result = strings.Join(strings.Fields(fmt.Sprintf("%d", u)), ",")
}
return []byte(result), nil
}
type Test struct {
Name string
Array JSONableSlice
}
func main() {
t := &Test{"Go", []uint8{'h', 'e', 'l', 'l', 'o'}}
m, err := json.Marshal(t)
if err != nil {
fmt.Println(err)
}
fmt.Printf("%s", m) // {"Name":"Go","Array":[104,101,108,108,111]}
}
http://play.golang.org/p/6aURXw8P5d
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