Golang操作結構體、Map轉化為JSON

結構體生成Json

package main

import (
    "encoding/json"
    "fmt"
)

type IT struct {
    Company string `json:"-"` //此字段不會輸出到屏幕
    //Company  string   `json:"company"`       這樣打印輸出別名首字母就會小寫(二次編碼)
    Subjects []string `json:"subjects"` //二次編碼
    IsOk     bool     `json:",string"`
    Price    float64  `json:",string"`
}

func main() {
    //定義一個結構體變量，同時初始化
    s := IT{"itcast", []string{"Golang", "PHP", "Java", "C++"}, true, 666.666}

    //編碼，根據內容生成json文本
    //buf, err := json.Marshal(s)
    //buf =  {"subjects":["Golang","PHP","Java","C++"],"IsOk":"true","Price":"666.666"}
    buf, err := json.MarshalIndent(s, "", "    ") //格式化編碼
    if err != nil {
        fmt.Println("err = ", err)
        return
    }

    fmt.Println("buf = ", string(buf))
}

　　

//結果
buf =  {
        "subjects": [   //首字母小寫
               "Golang",
                "PHP",
                "Java",
                "C++"
        ],
       "IsOk": "true",   //string類型
       "Price": "666.666"
}

　　Json轉成結構體

package main

import (
    "encoding/json"
    "fmt"
)

type IT struct {
    Address   string   `json:"address"`
    Languages []string `json:"languages"` //二次編碼
    Status    bool     `json:"isok"`
    Price     float64  `json:"price"`
}

func main() {

    jsonBuf := `
    {
    "address": "北京",
    "languages": [
        "Golang",
        "PHP",
        "Java",
        "Python"
    ],
    "status": true,
    "price": 666.666
}`

    var tmp IT                                   //定義一個結構體變量
    err := json.Unmarshal([]byte(jsonBuf), &tmp) //第二個參數要地址傳遞
    if err != nil {
        fmt.Println("err = ", err)
        return
    }
    //fmt.Println("tmp = ", tmp)
    fmt.Printf("tmp = %+v\n", tmp)

    type IT2 struct {
        Subjects []string `json:"languages"` //二次編碼
    }

    var tmp2 IT2
    err = json.Unmarshal([]byte(jsonBuf), &tmp2) //第二個參數要地址傳遞
    if err != nil {
        fmt.Println("err = ", err)
        return
    }
    fmt.Printf("tmp2 = %+v\n", tmp2)

}

　　

tmp = {Address:北京 Languages:[Golang PHP Java Python] Status:false Price:666.666}
tmp2 = {Subjects:[Golang PHP Java Python]}

　　Map生成Json

package main

import (
    "encoding/json"
    "fmt"
)

func main() {
    //創建一個map
    m := make(map[string]interface{}, 4) //因為類型多，可以用interface空接口
    m["address"] = "北京"
    m["languages"] = []string{"Golang", "PHP", "Java", "Python"}
    m["status"] = true
    m["price"] = 666.666

    //編碼成json
    //result, err := json.Marshal(m)
    //result =  {"address":"北京","languages":["Golang","PHP","Java","Python"],"price":666.666,"status":true}
    result, err := json.MarshalIndent(m, "", "    ")
    if err != nil {
        fmt.Println("err = ", err)
        return
    }
    fmt.Println("result = ", string(result))
}

　　

result =  {
        "address": "北京",
        "languages": [
                "Golang",
                "PHP",
                "Java",
                "Python"
        ],
        "price": 666.666,
        "status": true
}

　　Json轉化為Map

package main

import (
    "encoding/json"
    "fmt"
)

func main() {
    jsonBuf := `
    {
    "company": "itcast",
    "subjects": [
        "Go",
        "C++",
        "Python",
        "Test"
    ],
    "isok": true,
    "price": 666.666
}`

    //創建一個map
    m := make(map[string]interface{}, 4)

    err := json.Unmarshal([]byte(jsonBuf), &m) //第二個參數要地址傳遞
    if err != nil {
        fmt.Println("err = ", err)
        return
    }
    fmt.Printf("m = %+v\n", m)

    //    var str string
    //    str = string(m["company"]) //err， 無法轉換
    //    fmt.Println("str = ", str)

    var str string

    //類型斷言, 值，它是value類型
    for key, value := range m {
        //fmt.Printf("%v ============> %v\n", key, value)
        switch data := value.(type) {
        case string:
            str = data
            fmt.Printf("map[%s]的值類型為string, value = %s\n", key, str)
        case bool:
            fmt.Printf("map[%s]的值類型為bool, value = %v\n", key, data)
        case float64:
            fmt.Printf("map[%s]的值類型為float64, value = %f\n", key, data)
        case []string:
            fmt.Printf("map[%s]的值類型為[]string, value = %v\n", key, data)
        case []interface{}:
            fmt.Printf("map[%s]的值類型為[]interface, value = %v\n", key, data)
        }

    }

}

　　

map[address]的值類型為string, value = 北京
map[Languages]的值類型為[]interface, value = [Golang PHP Java Python]
map[Status]的值類型為bool, value = true
map[price]的值類型為float64, value = 666.666000

　　[]interface{}轉json

package main
 
import (
    "encoding/json"
    "fmt"
)
func main(){
	var s []interface{}
	s = append(s,5)
	s = append(s,[]string{"Golang", "PHP", "Java", "Python"})
	s = append(s,map[string]string{"hello":"world"})
	result, err := json.MarshalIndent(s, "", "    ")
	if err != nil {
        fmt.Println("err = ", err)
        return
    }
	fmt.Println("result = ", string(result))
}

　　

result =  [
    5,
    [
        "Golang",
        "PHP",
        "Java",
        "Python"
    ],
    {
        "hello": "world"
    }
]