JSON is a 
 package to operate JSON data.

(1) Use the json.Marshal() method to convert the structure into a JSON string

Print: After serialization: {"Name": "tom", "Age": 12, "Skill": "football"}

(2) JSON To convert a string into a structure, you can use the json.Unmarshal() method

to print: After deserialization: Student={tom 12 football} , Name=tom

(3) How to realize that the name of the key can be customized after the structure is serialized

For the name of the customized key, you can specify it in the struct variable After printing a , you can see that the name of the key has changed to the name of the tag label we specified

After serialization: {"stu_name":"tom ","stu_age":12,"Skill":"football"}

func main()  {
	// map 转 Json字符串
	m := make(map[string]interface{})
	m["name"] = "jetty"
	m["age"] = 16

	data, err := json.Marshal(&m)
	if err != nil {
		fmt.Printf("序列化错误 err=%v\n", err)
		return
	}
	fmt.Println("序列化后: ", string(data))    // 打印: 序列化后:  {"age":16,"name":"jetty"}

	// Json字符串 转 map
	str := `{"age":25,"name":"car"}`
	err = json.Unmarshal([]byte(str), &m)
	if err != nil {
		fmt.Printf("反序列化错误 err=%v\n", err)
		return
	}
	fmt.Printf("反序列化后: map=%v, name=%v\n", m, m["name"])
	// 打印: 反序列化后: map=map[age:25 name:car], name=car}
    If the first letter of the variable is lowercase, it is private. Because the reflection information cannot be obtained, it cannot be transferred.
  • If the first letter of the variable is capitalized, it is public. It can be converted normally regardless of whether tags are added or not. Variables with tags will be displayed according to the name of the tag.
Example: Through printing, we found that lowercase variables, such as age and addr, were not converted into json data. Summary:
If the first letter is lowercase, it cannot be converted to json data regardless of whether it is added with a tag, while if it is uppercase, it can be aliased with a tag, and if it is not added with a tag, it will be converted into json data. The fields are consistent with the original names of the structure variables 
type User struct {
	Name string    `json:"u_name"`
	Password string `json:"password"`
	Email string `json:"email"`}func main()  {
	user := User{"admin", "pwd", "user@163.com"}
	person := Person{23, "上海"}
	// 忽略掉 Password 字段
	data, _ := json.Marshal(struct {
		*User
		Password string `json:"password,omitempty"`
	}{User: &user})
	fmt.Println("忽略字段: ", string(data))  // 打印: 忽略字段: {"u_name":"admin","email":"user@163.com"}}
Ignore fields: {"u_name":"admin","email":"user@163.com"}} 
data, _ = json.Marshal(struct {
	*User
	Skill string `json:"skill"`  // 临时添加额外的 Skill字段}{
	User: &user,
	Skill: "football",})fmt.Println("添加额外字段: ", string(data))
Add additional fields: {"u_name":"admin","password":"pwd","email":"user@163.com","skill":"football"} 
type User struct {
	Name string    `json:"u_name"`
	Password string `json:"password"`
	Email string `json:"email"`}type Person struct {
	Age int
	Addr string `json:"addr"`}func main()  {
    // 初始化两个 struct
	user := User{"admin", "pwd", "user@163.com"}
	person := Person{23, "上海"}
	
	data, _ := json.Marshal(struct {
		*User		*Person	}{
		User: &user,
		Person: &person,
	})
	
	fmt.Println("合并两个struct: ", string(data))}
Merge two structs: {"u_name":"admin","password":"pwd","email" : "user@163.com", "Age": 23, "addr": "Shanghai"} 
emp := struct {                    // 创建匿名 struct
	Num int `json:"num,string"`}{15,}data, _ := json.Marshal(&emp)fmt.Println("数字转成字符串: ", string(data))       // 数字转成字符串: {"num":"15"}str := `{"Num":"25"}`_ = json.Unmarshal([]byte(str), &emp)fmt.Printf("字符串转成数字: Emp.Num=%v\n", emp.Num) // 字符串转成数字: Emp.Num=25
str = ` {"u_name":"system","password":"abc","email":"user2@163.com","Age":23,"addr":"杭州"}`var user2 Uservar person2 Person_ := json.Unmarshal([]byte(str), &struct {
	*User	*Person}{
	User: &user2,
	Person: &person2,})fmt.Printf("分成两个struct: User=%v, Person=%v\n", user2, person2)
is divided into two structs: User={system abc user2@163.com}, Person={23 Hangzhou}