Golang JSON encoding decoding

Golang "Encoding/json" package implements encoding and decoding of JSON objects

One, the code

Interface {}) ([]byte, error)

The Marshal function uses the following type-based default encoding format:

The Boolean type is encoded as a JSON Boolean type.

Values for floating-point, Integer, and number types are encoded as JSON numeric types.

The string is encoded as a JSON string. The angle brackets "<" and ">" are escaped as "\u003c" and "\u003e" to avoid some browser bar JSON output incorrectly interpreted as HTML. For the same reason, "&" is escaped as "\u0026".

The values for array and slice types are encoded as JSON arrays, but []byte encoded as base64 encoded strings and nil slices are encoded as null.

The value of the struct is encoded as a JSON object. Each export field becomes a member of the object

Example:

1 Package Main2 3 Import (4     "FMT"5     "Encoding/json"6 )7 Func Main () {8Type Userstruct{9NamestringTenAgeint One     } AUser: =user{ -Name:"Tom", -Age:3, the     } -B, err: =JSON. Marshal (user) -     ifErr! =Nil { -Fmt. Println ("json Marshal fail:", Err) +     } -Fmt. Println (string(b)) +}

Output:

{"Name":"Tom","Age":  3}

1 non-exportable fields are not encoded

Example:

struct {        string             int} User: = user{Name:         " Tom " , age        :3,    }    B, _:= json. Marshal (user)    FMT. Println (string(b))

Output:

{"Name":"Tom"}

2 The encoded JSON object can be changed through the structure tag

Example:

 type User struct  {Name  string  ' Json:"  name  Span style= "COLOR: #800000" > "  ' age  int ' Json: " ageeeeeeeeeeeeeeeeee   " "} User:  = user{ Name:   " tom  "  , Age:  3  ,} B, _:  = JSON. Marshal (user) fmt. Println ( string  (b)) 

Output:

{"name":"Tom","ageeeeeeeeeeeeeeeeee ":3}

3 Complex structure Code:

The pointer is encoded to the value it points to

Slice encoding Array

The value of the struct is encoded as a JSON object

Example:

    //Complex structure Coding//basic type pointers, struct pointers, slices, slice pointers,Type Contactstruct{AddrstringPhonestring} type Userstruct{Namestring Age*intC1*Contact C2 []contact C3 []*Contact } Age:= -C1:= contact{"Beijing","12345"} CARR:= [...] contact{contact{"Beijing","11111"},contact{"Shenzhen","22222"},contact{"Shanghai","33333"}} C2:= carr[:2] C3:= Make ([]*contact,0) C3= Append (C3, &carr[0]) C3= Append (C3, &carr[1]) User:=user{Name:"Tom", Age:&Age , C1:&C1, C2:C2, C3:C3,} fmt. Printf ("struct:%v\n", user) B, _:=JSON. Marshal (user) fmt. Println ("JSON:",string(b))

Output:

struct: {Tom0xc04204a1c8 0xc042044580[{Beijing11111} {Shenzhen22222}] [0xc042086000 0xc042086020]}json: {"Name":"Tom"," Age": -,"C1":{"Addr":"Beijing","Phone":"12345"},"C2":[{"Addr":"Beijing","Phone":"11111"},{"Addr":"Shenzhen","Phone":"22222"}],"C3":[{"Addr":"Beijing","Phone":"11111"},{"Addr":"Shenzhen","Phone":"22222"}]}

Second, decoding

Func unmarshal (data []byteinterface{}) Error

Example

//JSON decoding testType Contactstruct{AddrstringPhonestring} type Userstruct{Namestring Age*intC1*Contact C2 []contact C3 []*Contact } User:=user{} J:= `{                "Name":"Tom",                " Age": -,                "C1": {                    "Addr":"Beijing",                    "Phone":"12345"                },                "C2": [{                    "Addr":"Beijing",                    "Phone":"11111"                }, {                    "Addr":"Shenzhen",                    "Phone":"22222"                }],                "C3": [{                    "Addr":"Beijing",                    "Phone":"11111"                }, {                    "Addr":"Shenzhen",                    "Phone":"22222"}]} ' err:= json. Unmarshal ([]byte(j), &user)ifErr! =Nil {fmt. Println ("JSON unmarshal fail!")} FMT. Printf ("%v\n", user) fmt. Println (*user. Age) Fmt. Println (*user. C1) fmt. Println (*user. c3[0])

Output

0xc04204a3a8 0xc0420447a0 11111 22222}] [0xc0420448600xc042044880]}12345   11111}

Reference: Go language standard library document Chinese version

Golang JSON encoding decoding