golang "encoding/json"包实现了json对象的编解码
https://www.cnblogs.com/fhb2011/p/8975184.html
一、编码
func Marshal(v interface{}) ([]byte, error)
Marshal函数使用下面的基于类型的默认编码格式：
布尔类型编码为json布尔类型。
浮点数、整数和Number类型的值编码为json数字类型。
字符串编码为json字符串。角括号"<"和">"会转义为"\u003c"和"\u003e"以避免某些浏览器吧json输出错误理解为HTML。基于同样的原因，"&"转义为"\u0026"。
数组和切片类型的值编码为json数组，但[]byte编码为base64编码字符串，nil切片编码为null。
结构体的值编码为json对象。每一个导出字段变成该对象的一个成员
Example:
package main
import(
"fmt"
"encoding/json"
)
func main() {
type User struct{
Name string
Age int
}
user := User{
Name:"tom",
Age:3,
}
b, err := json.Marshal(user)
if err != nil {
fmt.Println("json Marshal fail:", err)
}
fmt.Println(string(b))
}Output:
{"Name":"tom","Age":3}
1 不可导出字段，不会被编码
Example:
复制代码
type User struct{
Name string
age int
}
user := User{
Name:"tom",
age:3,
}
b, _ := json.Marshal(user)
fmt.Println(string(b))
复制代码
Output:
{"Name":"tom"}
2 可通过结构体标签，改变编码的json对象
Example:
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type User struct{
Name string json:"name"
Age int MARKDOWN_HASHab3cc8bd113dd144267d0dea32e61e15MARKDOWNHASH
}
user := User{
Name:"tom",
Age:3,
}
b, := json.Marshal(user)
fmt.Println(string(b))
复制代码
Output:
{"name":"tom","ageeeeeeeeeeeeeeeeee":3}
3 复杂结构体编码：
指针编码为它指向的值
切片编码为数组
结构体的值编码为json对象
Example:
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// 复杂结构体编码
//基本类型指针，结构体指针,切片，切片指针，
type Contact struct {
Addr string
Phone string
}
type User struct {
Name string
Age *int
C1 *Contact
C2 []Contact
C3 []*Contact
}
age := 20
c1 := Contact{"北京","12345"}
cArr := [...]Contact{Contact{"北京","11111"},Contact{"深圳","22222"},Contact{"上海","33333"}}
c2 := cArr[:2]
c3 := make([]*Contact,0)
c3 = append(c3, &cArr[0])
c3 = append(c3, &cArr[1])
user := User{
Name: "Tom",
Age: &age,
C1: &c1,
C2: c2,
C3: c3,
}
fmt.Printf("struct: %v\n", user)
b, _ := json.Marshal(user)
fmt.Println("json: ", string(b))复制代码
Output:
struct: {Tom 0xc04204a1c8 0xc042044580 [{北京 11111} {深圳 22222}] [0xc042086000 0xc042086020]}
json: {"Name":"Tom","Age":20,"C1":{"Addr":"北京","Phone":"12345"},"C2":[{"Addr":"北京","Phone":"11111"},{"Addr":"深圳","Phone":"22222"}],"C3":[{"Addr":"北京","Phone":"11111"},{"Addr":"深圳","Phone":"22222"}]}
二、解码
func Unmarshal(data []byte, v interface{}) error
Example
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//json解码 测试
type Contact struct {
Addr string
Phone string
}
type User struct {
Name string
Age *int
C1 *Contact
C2 []Contact
C3 []*Contact
}
user := User{}
j := `{
"Name": "Tom",
"Age": 20,
"C1": {
"Addr": "北京",
"Phone": "12345"
},
"C2": [{
"Addr": "北京",
"Phone": "11111"
}, {
"Addr": "深圳",
"Phone": "22222"
}],
"C3": [{
"Addr": "北京",
"Phone": "11111"
}, {
"Addr": "深圳",
"Phone": "22222"
}]
}`
err := json.Unmarshal([]byte(j), &user)
if err != nil {
fmt.Println("json Unmarshal fail!")
}
fmt.Printf("%v\n", user)
fmt.Println(*user.Age)
fmt.Println(*user.C1)
fmt.Println(*user.C3[0])复制代码
Output
{Tom 0xc04204a3a8 0xc0420447a0 [{北京 11111} {深圳 22222}] [0xc042044860 0xc042044880]}
20
{北京 12345}
{北京 11111}