Golang 学习笔记09：泛型

泛型函数

定义一个加法函数，如果调用传参类型不符会报错

func plus(n1, n2 int) int {
	return n1 + n2
}
func main() {
	res := plus(1, 2)
	println(res)
	var u1 ,u2 =uint(2), uint(3)
	plus(u1,u2)
}

使用泛型，这里的T是占位符

func plus[T int | uint](n1, n2 T) T {
	return n1 + n2
}

多个泛型

func myPrint[T int, K string | int](n1 T, n2 K) {

}

如果比较多的情况使用interface

type Number interface {
	int | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | uint
}
func myPrint[T int, K string | Number](n1 T, n2 K) {

}

泛型结构体

假设一个响应的结构体序列化

type Response struct {
	Code int    `json:"code"`
	Msg  string `json:"msg"`
	Data any    `json:"data"`
}
type User struct {
		Name string `json:"name"`
		Age  int    `json:"age"`
	}

	res := Response{
		Code: 1001,
		Msg:  "成功",
		Data: User{
			Name: "张三",
			Age:  18,
		},
	}
	byteData, _ := json.Marshal(res)
	fmt.Println(string(byteData))

{"code":1001,"msg":"成功","data":{"name":"张三","age":18}}

假设两个json序列化

type User struct {
	Name string `json:"name"`
	Age  int    `json:"age"`
}
type UserInfo struct {
	Name   string `json:"name"`
	Gender string `json:"gender"`
}

user := Response{
	Code: 1001,
	Msg:  "成功",
	Data: User{
		Name: "张三",
		Age:  18,
	},
}
//json序列化
byteData, _ := json.Marshal(user)
fmt.Println(string(byteData))
userInfo := Response{
	Code: 1001,
	Msg:  "成功",
	Data: UserInfo{
		Name:   "张三",
		Gender: "男",
	},
}
//json序列化
byteData, _ = json.Marshal(userInfo)
fmt.Println(string(byteData))

{"code":1001,"msg":"成功","data":{"name":"张三","age":18}}
{"code":1001,"msg":"成功","data":{"name":"张三","gender":"男"}}

反序列化

var user Response
json.Unmarshal([]byte(`{"code":1001,"msg":"成功","data":{"name":"张三","age":18}}`), &user)
fmt.Println(user)

{1001 成功 map[age:18 name:张三]}

注意：json.Unmarshal的第二个参数要带指针

可以看到，此时data是map，并不能使用.语法

解决办法，Response的Data就不能写成any类型了

type Response[T any] struct {
	Code int    `json:"code"`
	Msg  string `json:"msg"`
	Data T      `json:"data"`
}

指定反序列化的类型

var user Response[User]
	json.Unmarshal([]byte(`{"code":1001,"msg":"成功","data":{"name":"张三","age":18}}`), &user)
fmt.Println(user) //{1001 成功 {张三 18}}

此时就能使用.语法了

var user Response[User]
json.Unmarshal([]byte(`{"code":1001,"msg":"成功","data":{"name":"张三","age":18}}`), &user)
fmt.Println(user) //{1001 成功 {张三 18}}
var userInfo Response[UserInfo]
json.Unmarshal([]byte(`{"code":1001,"msg":"成功","data":{"name":"张三","gender":"男"}}`), &userInfo)
fmt.Println(userInfo) //{1001 成功 {张三 男}}

泛型切片

type MySlice[T int | string] []T
var mySlice = MySlice[int]{1, 2, 3}

泛型map

type MyMap[K string, V int | string] map[K]V
var myMap = MyMap[string, int]{"a": 1, "b": 2}