GO-json

目录

• 通过结构体生成json
• 通过map生成json
• json解析到结构体
• json解析到map

buf, err := json.MarshalIndent(s, "", " ") //格式化编码

package main

import (
	"encoding/json"
	"fmt"
)

//成员变量名首字母必须大写
type IT struct {
	Company  string   `json:"-"`        //此字段不会输出到屏幕
	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{"Go", "C++", "Python", "Test"}, true, 666.666}

	//编码，根据内容生成json文本
	//{"Company":"itcast","Subjects":["Go","C++","Python","Test"],"IsOk":true,"Price":666.666}
	//buf, err := json.Marshal(s)
	buf, err := json.MarshalIndent(s, "", "	") //格式化编码
	if err != nil {
		fmt.Println("err = ", err)
		return
	}
	fmt.Println(string(buf))
}

通过map生成json

package main

import (
	"encoding/json"
	"fmt"
)

func main() {
	//创建一个map
	m := make(map[string]interface{}, 4)
	m["company"] = "itcast"
	m["subjects"] = []string{"Go", "C++", "Python", "Test"}
	m["isok"] = true
	m["price"] = 666.666

	//编码成json
	//result, err := json.Marshal(m)
	result, err := json.MarshalIndent(m, "", "	")
	if err != nil {
		fmt.Println("err = ", err)
		return
	}
	fmt.Println("result = ", string(result))
}

json解析到结构体

err := json.Unmarshal([]byte(jsonBuf), &tmp) //第二个参数要地址传递

package main

import (
	"encoding/json"
	"fmt"
)

type IT struct {
	Company  string   `json:"company"`
	Subjects []string `json:"subjects"` //二次编码
	IsOk     bool     `json:"isok"`
	Price    float64  `json:"price"`
}

func main() {

	jsonBuf := `
	{
    "company": "itcast",
    "subjects": [
        "Go",
        "C++",
        "Python",
        "Test"
    ],
    "isok": 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\n", tmp)

	type IT2 struct {
		Subjects []string `json:"subjects"` //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\n", tmp2)

}

json解析到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\n", 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\n", key, value)
		switch data := value.(type) {
		case string:
			str = data
			fmt.Printf("map[%s]的值类型为string, value = %s\n", key, str)
		case bool:
			fmt.Printf("map[%s]的值类型为bool, value = %v\n", key, data)
		case float64:
			fmt.Printf("map[%s]的值类型为float64, value = %f\n", key, data)
		case []string:
			fmt.Printf("map[%s]的值类型为[]string, value = %v\n", key, data)
		case []interface{}:
			fmt.Printf("map[%s]的值类型为[]interface, value = %v\n", key, data)
		}

	}

}