golang jsoniter extension 处理动态字段的实现方法

type MyTime struct {
	t    time.Time
}

package main

import (
	"fmt"
	"reflect"
	"strconv"
	"time"
	"unsafe"

	jsoniter "github.com/json-iterator/go"
	"github.com/modern-go/reflect2"
)

type sampleExtension struct {
	jsoniter.DummyExtension
}

type wrapEncoder struct {
	encodeFunc  func(ptr unsafe.Pointer, stream *jsoniter.Stream)
	isEmptyFunc func(ptr unsafe.Pointer) bool
	decodeFunc  func(ptr unsafe.Pointer, iter *jsoniter.Iterator)
}

func (enc *wrapEncoder) Encode(ptr unsafe.Pointer, stream *jsoniter.Stream) {
	enc.encodeFunc(ptr, stream)
}

func (codec *wrapEncoder) Decode(ptr unsafe.Pointer, iter *jsoniter.Iterator) {
	codec.decodeFunc(ptr, iter)
}

func (enc *wrapEncoder) IsEmpty(ptr unsafe.Pointer) bool {
	if enc.isEmptyFunc == nil {
		return false
	}

	return enc.isEmptyFunc(ptr)
}

// 这里统一改用 unix seconds 进行输出
func (e *sampleExtension) CreateEncoder(typ reflect2.Type) jsoniter.ValEncoder {
	if typ.Kind() == reflect.Struct && typ.Type1().PkgPath() == "time" && typ.String() == "time.Time" {

		return &wrapEncoder{
			func(ptr unsafe.Pointer, stream *jsoniter.Stream) {
				t := *(*time.Time)(ptr)
				data := strconv.Itoa(int(t.Unix()))
				stream.WriteRaw(data)
			},
			nil,
			nil,
		}
	}

	return nil
}

func (e *sampleExtension) CreateDecoder(typ reflect2.Type) jsoniter.ValDecoder {
	if typ.Kind() == reflect.Struct && typ.Type1().PkgPath() == "time" && typ.String() == "time.Time" {
		return &wrapEncoder{
			decodeFunc: func(ptr unsafe.Pointer, iter *jsoniter.Iterator) {
				switch iter.WhatIsNext() {
				case jsoniter.NumberValue: // 兼容 unix 数字解析
					timeUnix := iter.ReadInt()
					newTime := time.Unix(int64(timeUnix), 0)
					*(*time.Time)(ptr) = newTime

				case jsoniter.NilValue:
					iter.Skip()

				case jsoniter.StringValue:
					timeStr := iter.ReadString()
					newTime, err := time.Parse(time.RFC3339, timeStr)
					if err != nil {
						fmt.Println("Unmarshal err", err)
					}
					*(*time.Time)(ptr) = newTime

				}
			},
		}
	}

	return nil
}

type Person struct {
	Birth time.Time `json:"birth"`
}

func main() {
	extension := &sampleExtension{}
	jsoniterAPI := jsoniter.Config{}.Froze()
	jsoniterAPI.RegisterExtension(extension)
	var p1 = Person{
		Birth: time.Now(),
	}
	j, err := jsoniterAPI.MarshalToString(p1)
	if err != nil {
		panic(err)
	}
	fmt.Println(j)

	var p2 Person
	err = jsoniterAPI.Unmarshal([]byte(`{"birth": 1680254527}`), &p2)
	if err != nil {
		panic(err)
	}
	fmt.Println("p2", p2)

	var p3 Person
	err = jsoniterAPI.Unmarshal([]byte(`{"birth": "2023-03-21T07:20:04+00:00"}`), &p3)
	if err != nil {
		panic(err)
	}
	fmt.Println("p3", p3)

	var p4 Person
	err = jsoniterAPI.Unmarshal([]byte(`{"birth": null}`), &p4)
	if err != nil {
		panic(err)
	}
	fmt.Println("p4", p4)
}