go json解析Marshal和Unmarshal

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第一次，站长亲自招 Gopher 了>>>

http://www.tuicool.com/articles/BFruI3

go语言提供一个json解析的包。见 http://golang.org/pkg/encoding/json/

官方同时提供了一篇文章 JSON and Go 讲述json包的用法，该文章同时存在中文翻译： JSON与Go 。

看过上述两篇文章后，基本使用应该就没问题了。

同时，贴几个官方的例子，方便理解。
Decoder:

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package main
import (
"encoding/json"
"fmt"
"io"
"log"
"strings"
)
func main ( ) {
const jsonStream = `
{ "Name" : "Ed" , "Text" : "Knock knock." }
{ "Name" : "Sam" , "Text" : "Who's there?" }
{ "Name" : "Ed" , "Text" : "Go fmt." }
{ "Name" : "Sam" , "Text" : "Go fmt who?" }
{ "Name" : "Ed" , "Text" : "Go fmt yourself!" }
`
type Message struct {
Name , Text string
}
dec := json. NewDecoder ( strings. NewReader ( jsonStream ) )
for {
var m Message
if err := dec. Decode ( & m ) ; err == io. EOF {
break
} else if err != nil {
log . Fatal ( err )
}
fmt. Printf ( "%s: %s \n " , m. Name , m. Text )
}
}

Marshal:

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package main
import (
"encoding/json"
"fmt"
"os"
)
func main ( ) {
type ColorGroup struct {
ID int
Name string
Colors [ ] string
}
group := ColorGroup {
ID : 1 ,
Name : "Reds" ,
Colors : [ ] string { "Crimson" , "Red" , "Ruby" , "Maroon" } ,
}
b , err := json. Marshal ( group )
if err != nil {
fmt. Println ( "error:" , err )
}
os. Stdout . Write ( b )
}

RawMessage :

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package main
import (
"encoding/json"
"fmt"
"log"
)
func main ( ) {
type Color struct {
Space string
Point json. RawMessage // delay parsing until we know the color space
}
type RGB struct {
R uint8
G uint8
B uint8
}
type YCbCr struct {
Y uint8
Cb int8
Cr int8
}
var j = [ ] byte ( ` [
{ "Space" : "YCbCr" , "Point" : { "Y" : 255 , "Cb" : 0 , "Cr" : - 10 } } ,
{ "Space" : "RGB" , "Point" : { "R" : 98 , "G" : 218 , "B" : 255 } }
] ` )
var colors [ ] Color
err := json. Unmarshal ( j , & colors )
if err != nil {
log . Fatalln ( "error:" , err )
}
for _ , c := range colors {
var dst interface { }
switch c. Space {
case "RGB" :
dst = new ( RGB )
case "YCbCr" :
dst = new ( YCbCr )
}
err := json. Unmarshal ( c. Point , dst )
if err != nil {
log . Fatalln ( "error:" , err )
}
fmt. Println ( c. Space , dst )
}
}

Unmarshal:

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package main
import (
"encoding/json"
"fmt"
)
func main ( ) {
var jsonBlob = [ ] byte ( ` [
{ "Name" : "Platypus" , "Order" : "Monotremata" } ,
{ "Name" : "Quoll" , "Order" : "Dasyuromorphia" }
] ` )
type Animal struct {
Name string
Order string
}
var animals [ ] Animal
err := json. Unmarshal ( jsonBlob , & animals )
if err != nil {
fmt. Println ( "error:" , err )
}
fmt. Printf ( "%+v" , animals )
}