encoding/json

这个包可以实现json的编码和解码，就是将json字符串转换为struct，或者将struct转换为json。

核心的两个函数


func Marshal(v interface{}) ([]byte, error)

将struct编码成json，可以接收任意类型


func Unmarshal(data []byte, v interface{}) error

将json转码为struct结构体

两个核心结构体


type Decoder struct {
    // contains filtered or unexported fields
}

从输入流读取并解析json


type Encoder struct {
    // contains filtered or unexported fields
}

结构体转换为json


package main

import (
	"encoding/json"
	"fmt"
)

type Person struct {
	Name  string
	Age   int
	Email string
}

func main() {
	p := Person{
		"lzc",
		18,
		"hybpjx@163.com",
	}
	b, _ := json.Marshal(p)
	fmt.Printf("b:%v\n", string(b))
	// {"Name":"lzc","Age":18,"Email":"hybpjx@163.com"}
}

json转换为结构体


package main
import (
    "encoding/json"
    "fmt"
)
type Person struct {
    Name  string
    Age   int
    Email string
}

func Unmarshal() {
    b1 := []byte(`{"Name":"lzc","Age":18,"Email":"hybpjx@163.com"}`)
    var m Person
    json.Unmarshal(b1, &m)
    fmt.Printf("m: %v\n", m)
}

func main() {
    Unmarshal()
}

解析嵌套引用类型


package main

import (
    "encoding/json"
    "fmt"
)

type Person struct {
    Name  string
    Age   int
    Email string
    Parent []string
}

func main() {
    p := Person{
        Name: "tom",
        Age: 20,
        Email: "tom@gmail.com",
        Parent: []string{"big tom", "big kite"},
    }

    b, _ := json.Marshal(p)
    fmt.Printf("b: %v\n", string(b))
    // {"Name":"tom","Age":20,"Email":"tom@gmail.com","Parent":["big tom","big kite"]}
}

io流Reader Writer可以扩展到http websocket等场景


package main

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

func main() {
	f, _ := os.Open("a.json")
	defer f.Close()
	d := json.NewDecoder(f)
	var v map[string]interface{}
	d.Decode(&v)
	fmt.Printf("v：%v\n", v)
}

写入文件


package main

import (
	"encoding/json"
	"os"
)

func main() {
	type Person struct {
		Name  string
		Age   int
		Email string
	}
	p := Person{
		"lzc",
		18,
		"hybpjx@163.com",
	}
	f, _ := os.OpenFile("a.json", os.O_WRONLY, 0777)
	defer f.Close()
	e:=json.NewEncoder(f)
	e.Encode(p)

}