json map 和 struct 编码对比

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12

type Object struct {
	Xvlbzgbaic string `json:"xvlbzgbaic"`
	Krbemfdzdc string `json:"krbemfdzdc"`
	Rzlntxyeuc string `json:"rzlntxyeuc"`
	Ctzkjkziva string `json:"ctzkjkziva"`
	Orsufumaps string `json:"orsufumaps"`
	Hyevwbtcml string `json:"hyevwbtcml"`
	Baatlyhdao string `json:"baatlyhdao"`
	Fkfohsvvxs string `json:"fkfohsvvxs"`
	Pqwarpxptp string `json:"pqwarpxptp"`
	Orvaukawww string `json:"orvaukawww"`
}

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19

	obj := Object{}
	json.Unmarshal([]byte(str), &obj)

	start := time.Now()
	for i := 0; i < 1000000; i++ {
		json.Marshal(obj)
	}

	fmt.Println(time.Since(start))

	maps := map[string]string{}
	json.Unmarshal([]byte(str), &maps)

	start = time.Now()
	for i := 0; i < 1000000; i++ {
		json.Marshal(maps)
	}
	// 
	fmt.Println(time.Since(start))

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30

// go/src/encoding/json/encode.go 
func (me *mapEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) {
	if v.IsNil() {
		e.WriteString("null")
		return
	}
	e.WriteByte('{')

	// Extract and sort the keys.
	keys := v.MapKeys()
	sv := make([]reflectWithString, len(keys))
	for i, v := range keys {
		sv[i].v = v
		if err := sv[i].resolve(); err != nil {
			e.error(&MarshalerError{v.Type(), err})
		}
	}
    // 在输出前会做key 的排序，最后按照key 排序的结果做输出
	sort.Slice(sv, func(i, j int) bool { return sv[i].s < sv[j].s })

	for i, kv := range sv {
		if i > 0 {
			e.WriteByte(',')
		}
		e.string(kv.s, opts.escapeHTML)
		e.WriteByte(':')
		me.elemEnc(e, v.MapIndex(kv.v), opts)
	}
	e.WriteByte('}')
}

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40

// go/src/encoding/json/encode.go


type structEncoder struct {
	fields    []field
	fieldEncs []encoderFunc
}

func newStructEncoder(t reflect.Type) encoderFunc {
	fields := cachedTypeFields(t) // 从cache 中获取fields
	se := &structEncoder{
		fields:    fields,
		fieldEncs: make([]encoderFunc, len(fields)),
	}
	for i, f := range fields {
		se.fieldEncs[i] = typeEncoder(typeByIndex(t, f.index))
	}
	return se.encode
}

func (se *structEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) {
	e.WriteByte('{')
	first := true
	for i, f := range se.fields {   // fields 被缓存在structEncoder 结构体中
		fv := fieldByIndex(v, f.index)
		if !fv.IsValid() || f.omitEmpty && isEmptyValue(fv) {
			continue
		}
		if first {
			first = false
		} else {
			e.WriteByte(',')
		}
		e.string(f.name, opts.escapeHTML)
		e.WriteByte(':')
		opts.quoted = f.quoted
		se.fieldEncs[i](e, fv, opts)
	}
	e.WriteByte('}')
}