官方的json库, 只支持整体的序列化与反序列化. 像其它语言的库, json库都支持单个getValue/setValue这类操作.
找了下golang相关的开源json库, GJSON star数不错，支持的查询功能很丰富. 但是没有写入接口. 找了一圈也没有
找到有写入功能的json库. 能想到的只有定义类型序列化或map序列化了. 以下是正文, 翻译自项目readme:
go get$ go get -u github.com/tidwall/gjson
获取值
.package main
import "github.com/tidwall/gjson"
const json = `{"name":{"first":"Janet","last":"Prichard"},"age":47}`
func main() {
value := gjson.Get(json, "name.last")
println(value.String())
}
输出结果:
Prichard
同时有 GetMany 方法批量获取值, 也有 GetBytes 方法获取字节切片.
路径解析
..{
"name": {"first": "Tom", "last": "Anderson"},
"age":37,
"children": ["Sara","Alex","Jack"],
"fav.movie": "Deer Hunter",
"friends": [
{"first": "Dale", "last": "Murphy", "age": 44},
{"first": "Roger", "last": "Craig", "age": 68},
{"first": "Jane", "last": "Murphy", "age": 47}
]
}
"name.last" >> "Anderson"
"age" >> 37
"children" >> ["Sara","Alex","Jack"]
"children.#" >> 3
"children.1" >> "Alex"
"child*.2" >> "Jack"
"c?ildren.0" >> "Sara"
"fav\.movie" >> "Deer Hunter"
"friends.#.first" >> ["Dale","Roger","Jane"]
"friends.1.last" >> "Craig"
#[...]==!=<<=>>=friends.#[last=="Murphy"].first >> "Dale"
friends.#[last=="Murphy"]#.first >> ["Dale","Jane"]
friends.#[age>45]#.last >> ["Craig","Murphy"]
friends.#[first%"D*"].last >> "Murphy"
JSON 行
..比如:
{"name": "Gilbert", "age": 61}
{"name": "Alexa", "age": 34}
{"name": "May", "age": 57}
{"name": "Deloise", "age": 44}
..# >> 4
..1 >> {"name": "Alexa", "age": 34}
..3 >> {"name": "Deloise", "age": 44}
..#.name >> ["Gilbert","Alexa","May","Deloise"]
..#[name="May"].age >> 57
ForEachLinesgjson.ForEachLine(json, func(line gjson.Result) bool{
println(line.String())
return true
})
Result Type
stringnumberboolnullResultbool, for JSON booleans
float64, for JSON numbers
string, for JSON string literals
nil, for JSON null
直接访问value:
result.Type // can be String, Number, True, False, Null, or JSON
result.Str // holds the string
result.Num // holds the float64 number
result.Raw // holds the raw json
result.Index // index of raw value in original json, zero means index unknown
有各种各样的方便的函数可以获取结果:
result.Exists() bool
result.Value() interface{}
result.Int() int64
result.Uint() uint64
result.Float() float64
result.String() string
result.Bool() bool
result.Time() time.Time
result.Array() []gjson.Result
result.Map() map[string]gjson.Result
result.Get(path string) Result
result.ForEach(iterator func(key, value Result) bool)
result.Less(token Result, caseSensitive bool) bool
result.Value()interface{}result.Array()boolean >> bool
number >> float64
string >> string
null >> nil
array >> []interface{}
object >> map[string]interface{}
64-bit integers
result.Int()result.Uint()result.Int() int64 // -9223372036854775808 to 9223372036854775807
result.Uint() int64 // 0 to 18446744073709551615
读取嵌套数组
假如你想从下列json获取所有的lastName:
{
"programmers": [
{
"firstName": "Janet",
"lastName": "McLaughlin",
}, {
"firstName": "Elliotte",
"lastName": "Hunter",
}, {
"firstName": "Jason",
"lastName": "Harold",
}
]
}
programmers.#.lastNameresult := gjson.Get(json, "programmers.#.lastName")
for _, name := range result.Array() {
println(name.String())
}
你同样能获取数组里的对象:
name := gjson.Get(json, `programmers.#[lastName="Hunter"].firstName`)
println(name.String()) // prints "Elliotte"
对象或数组迭代
ForEachfalse简易的Parse和Get
Parse(json)result.Get(path)比如, 下面的几种情况都将返回相同的结果:
gjson.Parse(json).Get("name").Get("last")
gjson.Get(json, "name").Get("last")
gjson.Get(json, "name.last")
检查value是否存在
有时你想要知道值是否存在.
value := gjson.Get(json, "name.last")
if !value.Exists() {
println("no last name")
} else {
println(value.String())
}
// Or as one step
if gjson.Get(json, "name.last").Exists() {
println("has a last name")
}
验证JSON
Get*Parse*如果你读取的json来源不可预料, 那么你可以通过GJSON这么事先验证.
if !gjson.Valid(json) {
return errors.New("invalid json")
}
value := gjson.Get(json, "name.last")
反序列化到map
map[string]interface{}m, ok := gjson.Parse(json).Value().(map[string]interface{})
if !ok {
// not a map
}
## 处理Bytes
如果你的JSON包含字节数组切片, 与其调用`Get(string(data), path)`, 不如调用[GetBytes](https://godoc.org/github.com/tidwall/gjson#GetBytes)方法更优.
```go
var json []byte = ...
result := gjson.GetBytes(json, path)
gjson.GetBytes(json, path)result.Raw[]bytevar json []byte = ...
result := gjson.GetBytes(json, path)
var raw []byte
if result.Index > 0 {
raw = json[result.Index:result.Index+len(result.Raw)]
} else {
raw = []byte(result.Raw)
}
result.Indexresult.Raw[]byteresult.Index一次获取多个值
GetManyresults := gjson.GetMany(json, "name.first", "name.last", "age")
[]Result性能
测试了GJSON以及 encoding/json,
ffjson,
EasyJSON,
jsonparser,
and json-iterator
BenchmarkGJSONGet-8 3000000 372 ns/op 0 B/op 0 allocs/op
BenchmarkGJSONUnmarshalMap-8 900000 4154 ns/op 1920 B/op 26 allocs/op
BenchmarkJSONUnmarshalMap-8 600000 9019 ns/op 3048 B/op 69 allocs/op
BenchmarkJSONDecoder-8 300000 14120 ns/op 4224 B/op 184 allocs/op
BenchmarkFFJSONLexer-8 1500000 3111 ns/op 896 B/op 8 allocs/op
BenchmarkEasyJSONLexer-8 3000000 887 ns/op 613 B/op 6 allocs/op
BenchmarkJSONParserGet-8 3000000 499 ns/op 21 B/op 0 allocs/op
BenchmarkJSONIterator-8 3000000 812 ns/op 544 B/op 9 allocs/op
使用的JSON:
{
"widget": {
"debug": "on",
"window": {
"title": "Sample Konfabulator Widget",
"name": "main_window",
"width": 500,
"height": 500
},
"image": {
"src": "Images/Sun.png",
"hOffset": 250,
"vOffset": 250,
"alignment": "center"
},
"text": {
"data": "Click Here",
"size": 36,
"style": "bold",
"vOffset": 100,
"alignment": "center",
"onMouseUp": "sun1.opacity = (sun1.opacity / 100) * 90;"
}
}
}
每个操作都是在以下的搜索路径中进行旋转的:
widget.window.name
widget.image.hOffset
widget.text.onMouseUp
这些基准是在MacBook Pro 15" 2.8 GHz英特尔酷睿i7上运行的, 使用Go 1.8, 可以找到. here.