golang学习笔记--struct、json、map互相转化

结构体生成Json

package main

import (
	"encoding/json"
	"fmt"
)

type IT struct {
	Company string `json:"-"` //此字段不会输出到屏幕
	//Company  string   `json:"company"`  // 这样打印输出别名首字母就会小写(二次编码)
	Subjects []string `json:"subjects"` //二次编码
	IsOk     bool     `json:",string"`
	Price    float64  `json:",string"`
}

func main() {
	//定义一个结构体变量，同时初始化
	s := IT{"itcast", []string{"Golang", "PHP", "Java", "C++"}, true, 666.666}

	//编码，根据内容生成json文本
	//buf, err := json.Marshal(s)
	//buf =  {"subjects":["Golang","PHP","Java","C++"],"IsOk":"true","Price":"666.666"}
	buf, err := json.MarshalIndent(s, "", "    ") //格式化编码
	if err != nil {
		fmt.Println("err = ", err)
		return
	}

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

　　输出：

buf =  {
    "subjects": [
        "Golang",
        "PHP",
        "Java",
        "C++"
    ],
    "IsOk": "true",
    "Price": "666.666"
}

　　

Json转成结构体

package main

import (
	"encoding/json"
	"fmt"
)

type IT struct {
	Address   string   `json:"address"`
	Languages []string `json:"languages"` //二次编码
	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                                   //定义一个结构体变量
	err := json.Unmarshal([]byte(jsonBuf), &tmp) //第二个参数要地址传递
	if err != nil {
		fmt.Println("err = ", err)
		return
	}
	//fmt.Println("tmp = ", tmp)
	fmt.Printf("tmp = %+v
", tmp)

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

	var tmp2 IT2
	err = json.Unmarshal([]byte(jsonBuf), &tmp2) //第二个参数要地址传递
	if err != nil {
		fmt.Println("err = ", err)
		return
	}
	fmt.Printf("tmp2 = %+v
", tmp2)

}

　　输出：

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() {
	//创建一个map
	m := make(map[string]interface{}, 4) //因为类型多，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

	//编码成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))
}

　　输出：

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

　　

Json转化为Map

package main
 
import (
    "encoding/json"
    "fmt"
)
 
func main() {
    jsonBuf := `
    {
    "company": "itcast",
    "subjects": [
        "Go",
        "C++",
        "Python",
        "Test"
    ],
    "isok": true,
    "price": 666.666
}`
 
    //创建一个map
    m := make(map[string]interface{}, 4)
 
    err := json.Unmarshal([]byte(jsonBuf), &m) //第二个参数要地址传递
    if err != nil {
        fmt.Println("err = ", err)
        return
    }
    fmt.Printf("m = %+v
", m)
 
    //    var str string
    //    str = string(m["company"]) //err， 无法转换
    //    fmt.Println("str = ", str)
 
    var str string
 
    //类型断言, 值，它是value类型
    for key, value := range m {
        //fmt.Printf("%v ============> %v
", key, value)
        switch data := value.(type) {
        case string:
            str = data
            fmt.Printf("map[%s]的值类型为string, value = %s
", key, str)
        case bool:
            fmt.Printf("map[%s]的值类型为bool, value = %v
", key, data)
        case float64:
            fmt.Printf("map[%s]的值类型为float64, value = %f
", key, data)
        case []string:
            fmt.Printf("map[%s]的值类型为[]string, value = %v
", key, data)
        case []interface{}:
            fmt.Printf("map[%s]的值类型为[]interface, value = %v
", key, data)
        }
 
    }
 
}

　　输出：

m = map[company:itcast isok:true price:666.666 subjects:[Go C++ Python Test]]
map[company]的值类型为string, value = itcast
map[subjects]的值类型为[]interface, value = [Go C++ Python Test]
map[isok]的值类型为bool, value = true
map[price]的值类型为float64, value = 666.666000

　　

　[]interface{}转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))
}

　　输出：

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