go json解析Marshal和Unmarshal

Decoder:

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:

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 :

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:

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 )
}