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)
                }

        }

}