现在有一个json格式的字符串，应该怎么解析呢，这里总结了以下4种方法

1. json.Unmarshal

函数func json.Unmarshal(data []byte, v any) error就是用来解析json编码的data，然后将结果保存在指针v指向的值里

e.g.

package main

import (
	"encoding/json"
	"fmt"
)

type user struct {
	Name    string
	Married bool
	Address struct {
		City    string
		Country string
	}
}

func main() {
	user1 := `{
		"name": "tian",
		"married": false,
		"address": {
		  "city": "beijing",
		  "country": "China"
		}
	  }`
	user1Struct := &user{}
	json.Unmarshal([]byte(user1), user1Struct)
	fmt.Printf("解码后的结果为：%v", *user1Struct)
}

• 首先根据json数据的格式定义struct，用来保存解码后的值。这里首先定义了一个user结构体，然后通过json.Unmarshal进行解码
• 缺点很明显，如果json数据很复杂，自定义的struct就跟着复杂。

程序运行后的结果如下：

PS E:\goland-workspace\GolangLearning\Common\json数据处理\unmarshal> go run .\main.go
解码后的结果为：{tian false {beijing China}}

2. viper.ReadConfig

使用go get -u github.com/spf13/viper 进行下载

函数func viper.ReadConfig(in io.Reader) error用于从in中读取数据并解析

e.g.

package main

import (
	"fmt"
	"strings"

	"github.com/spf13/viper"
)

func main() {
	user1 := `{
		"name": "tian",
		"married": false,
		"address": {
		  "city": "beijing",
		  "country": "China"
		}
	  }`
	// 指定配置的类型为json
	viper.SetConfigType("json")
	// 读取数据
	if err := viper.ReadConfig(strings.NewReader(user1)); err != nil {
		fmt.Println(err)
	}
	fmt.Printf("数据的所有键值: %v\n", viper.AllKeys())
	fmt.Printf("解析后的数据：%v\n", viper.AllSettings())
	fmt.Printf("the type of \"married\" is %s\n", reflect.TypeOf(viper.Get("married")))
	fmt.Printf("The name is %s and the country is %s\n", viper.Get("name"), viper.Get("address.country"))
}

• 首先要通过viper.SetConfigType("json")指定要解析数据的格式，否则即使viper.ReadConfig返回值没有报错，也得不到解析后的结果。可以查看https://github.com/spf13/viper/issues/316
• 方法viper.Get()，viper.GetString()，viper.GetBool()等等可以方便获取键值，同时对于键值的类型也能很好的判断

程序运行后的结果如下：

PS E:\goland-workspace\GolangLearning\Common\json数据处理\viper> go run .\main.go
数据的所有键值: [address.city address.country name married]
解析后的数据：map[address:map[city:beijing country:China] married:false name:tian]
the type of "married" is bool
The name is tian and the country is China

3. simplejson.NewJson

使用go get -u "github.com/bitly/go-simplejson"进行下载

e.g.

package main

import (
	"fmt"

	"github.com/bitly/go-simplejson"
)

func main() {
	user1 := `{
		"name": "tian",
		"married": false,
		"address": {
		  "city": "beijing",
		  "country": "China"
		}
	  }`

	user1json, err := simplejson.NewJson([]byte(user1))
	if err != nil {
		fmt.Println(err)
	}
	name1, _ := user1json.Get("name").String()
	city1, _ := user1json.Get("address").Get("city").String()
	fmt.Printf("The name is %s and the city is %s", name1, city1)
}

程序运行后的结果如下：

PS E:\goland-workspace\GolangLearning\Common\json数据处理\simpleJson> go run .\main.go
The name is tian and the city is beijing

4. gojsonq.New().FromString()

使用go get -u github.com/thedevsaddam/gojsonq安装

e.g.

package main

import (
	"fmt"

	"github.com/thedevsaddam/gojsonq/v2"
)

func main() {
	user1 := `{
		"name": "tian",
		"married": false,
		"address": {
		  "city": "beijing",
		  "country": "China"
		}
	  }`

	user1json := gojsonq.New().FromString(user1)
	name1 := user1json.Find("name").(string)

	user1json.Reset()
	city1 := user1json.Find("address.city")
	fmt.Printf("The name is %s and the city is %v", name1, city1)
}

• 在第一次查询name之后，手动调用了一次Reset()方法。因为JSONQ对象在调用Find方法时，内部会记录当前的节点，下一个查询会从上次查找的节点开始

程序运行后的结果如下：

PS E:\goland-workspace\GolangLearning\Common\json数据处理\gojsonq> go run .\main.go
The name is tian and the city is beijing