JSON 是一种广泛使用的数据交换格式。 Golang 提供了多种编码和解码 API 来处理 JSON，包括使用encoding/json包的内置和自定义数据类型。
数据类型：用于解码和编码JSON的默认Golang数据类型如下：
- 用于 JSON 布尔值的 bool
- JSON 数字的 float64
- 字符串JSON字符串
- nil 表示 JSON null
- 数组作为 JSON 数组
- 映射或结构为 JSON 对象
1. 编码/编组结构： encoding/json包中的 Marshal()函数用于将数据编码为 JSON。
Syntax: func Marshal(v interface{}) ([]byte, error)
例子：
// Golang program to illustrate the
// concept of encoding using JSON
package main
import (
"fmt"
"encoding/json"
)
// declaring a struct
type Human struct{
// defining struct variables
Name string
Age int
Address string
}
// main function
func main() {
// defining a struct instance
human1 := Human{"Ankit", 23, "New Delhi"}
// encoding human1 struct
// into json format
human_enc, err := json.Marshal(human1)
if err != nil {
// if error is not nil
// print error
fmt.Println(err)
}
// as human_enc is in a byte array
// format, it needs to be
// converted into a string
fmt.Println(string(human_enc))
// converting slices from
// golang to JSON fomat
// defining an array
// of struct instance
human2 := []Human{
{Name: "Rahul", Age: 23, Address: "New Delhi"},
{Name: "Priyanshi", Age: 20, Address: "Pune"},
{Name: "Shivam", Age: 24, Address: "Bangalore"},
}
// encoding into JSON format
human2_enc, err := json.Marshal(human2)
if err != nil {
// if error is not nil
// print error
fmt.Println(err)
}
// printing encoded array
fmt.Println()
fmt.Println(string(human2_enc))
}
输出：
{"Name":"Ankit", "Age":23, "Address":"New Delhi"}
[{"Name":"Rahul", "Age":23, "Address":"New Delhi"}, {"Name":"Priyanshi", "Age":20, "Address":"Pune"}, {"Name":"Shivam", "Age":24, "Address":"Bangalore"}]
2. 解码/解组结构体： encoding/json包中的 Unmarshal()函数用于将数据从 JSON 解包或解码为结构体。
Syntax: func Unmarshal(data []byte, v interface{}) error
例子：
// Golang program to illustrate the
// concept of decoding using JSON
package main
import (
"fmt"
"encoding/json"
)
// declaring a struct
type Human struct{
// defining struct variables
Name string
Address string
Age int
}
// main function
func main() {
// defining a struct instance
var human1 Human
// data in JSON format which
// is to be decoded
Data := []byte(`{
"Name": "Deeksha",
"Address": "Hyderabad",
"Age": 21
}`)
// decoding human1 struct
// from json format
err := json.Unmarshal(Data, &human1)
if err != nil {
// if error is not nil
// print error
fmt.Println(err)
}
// printing details of
// decoded data
fmt.Println("Struct is:", human1)
fmt.Printf("%s lives in %s.\n", human1.Name, human1.Address)
// unmarshaling a JSON array
// to array type in Golang
// defining an array instance
// of struct type
var human2 []Human
// JSON array to be decoded
// to an array
Data2 := []byte(`
[
{"Name": "Vani", "Address": "Delhi", "Age": 21},
{"Name": "Rashi", "Address": "Noida", "Age": 24},
{"Name": "Rohit", "Address": "Pune", "Age": 25}
]`)
// decoding JSON array to
// human2 array
err2 := json.Unmarshal(Data2, &human2)
if err2 != nil {
// if error is not nil
// print error
fmt.Println(err2)
}
// printing decoded array
// values one by one
for i := range human2{
fmt.Println(human2[i])
}
}
输出：
Struct is: {Deeksha Hyderabad 21}
Deeksha lives in Hyderabad.
{Vani Delhi 21}
{Rashi Noida 24}
{Rohit Pune 25}