Go语言标准库之JSON编解码
Go语言标准库之JSON编解码
基本的类型
Go语言中的数据类型和JSON的数据类型的关系
- bool -> JSON boolean
- float64 -> JSON numbers
- string -> JSON strings
- nil -> JSON null
Struct to JSON
Go包encoding/json中的json.Marshal方法，可以将struct编码为JSON数据
package main
import (
"encoding/json"
"fmt"
"time"
)
type FruitBasket struct {
Name string
Fruit []string
Id int64 `json:"ref"`
private string // 这个字段不会被编码
Created time.Time
}
func main() {
basket := FruitBasket{
Name: "Standard",
Fruit: []string{"Apple", "Banana", "Orange"},
Id: 999,
private: "Second-rate",
Created: time.Now(),
}
jsonData, err := json.Marshal(basket)
if err != nil {
fmt.Println(err)
}
fmt.Println(string(jsonData))
}输出结果
{"Name":"Standard","Fruit":["Apple","Banana","Orange"],"ref":999,"Created":"2019-01-01T11:40:05.9885387+08:00"}- 只有
public字段才能被导出 json:tag可以定义导出字段的名称- nil导出为
null格式化输出 可以使用json.MarshalIndent方法来格式化输出的JSON数据
formatData, err := json.MarshalIndent(basket, "", " ")
fmt.Println(string(formatData))格式化输出结果是
{
"Name": "Standard",
"Fruit": [
"Apple",
"Banana",
"Orange"
],
"ref": 999,
"Created": "2019-01-01T11:45:49.0969176+08:00"
}JSON to Struct
Go包中json.Unmarshal方法，解析 JSON数据
jsonStr := []byte(`
{
"Name": "Standard",
"Fruit": [
"Apple",
"Banana",
"Orange"
],
"ref": 999,
"Created": "2019-01-01T11:45:49.0969176+08:00"
}
`)
var basketStruct FruitBasket
err = json.Unmarshal(jsonStr, &basketStruct)
if err != nil {
log.Println(err)
}
fmt.Println(basketStruct.Name, basketStruct.Fruit)
fmt.Println(basketStruct.Created)输出结果是
Standard [Apple Banana Orange]
2019-01-01 11:45:49.0969176 +0800 CST编码格式化任意类型的对象和数组
map[string]interface{}可以编码任意类型的 JSON对象
[]interface{}可以编码任意类型的JSON数组
arbitData := []byte(`{"Name":"Eve","Age":6,"Parents":["Alice","Bob"]}`)
var v interface{}
err = json.Unmarshal(arbitData, &v)
if err != nil {
log.Println(err)
}
data := v.(map[string]interface{})
for k, v := range data {
switch v := v.(type) {
case string:
fmt.Println(k, v, "(string)")
case float64:
fmt.Println(k, v, "(float64)")
case []interface{}:
fmt.Println(k, v, "(array)")
for i, u := range v {
fmt.Println(" ", i, u)
}
default:
fmt.Println(k, v, "(unknown)")
}
}输出结果是
Name Eve (string)
Age 6 (float64)
Parents [Alice Bob] (array)
0 Alice
1 Bob编解码JSON文件
Go中encoding/json中的json.Decoder和json.Encoder方法可以编解码JSON格式文件
例子：
jsonstr := `
{"Name": "Alice", "Age": 25}
{"Name": "Bob", "Age": 22}`
reader := strings.NewReader(jsonstr)
writer := os.Stdout
dec := json.NewDecoder(reader)
enc := json.NewEncoder(writer)
for {
var m map[string]interface{}
if err := dec.Decode(&m); err == io.EOF {
break
} else if err != nil {
log.Fatal(err)
}
for k := range m {
if k == "Age" {
delete(m, k)
}
}
if err = enc.Encode(&m); err != nil {
log.Println(err)
}
}输出结果是
{"Name":"Alice"}
{"Name":"Bob"}本文参与 腾讯云自媒体同步曝光计划，分享自作者个人站点/博客。
原始发表：2019-01-16 ，如有侵权请联系 cloudcommunity@tencent.com 删除
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