Go语言处理JSON之——利用Marshal生成json字符串（二）

上一篇文章中（地址为：https://blog.youkuaiyun.com/hp_cpp/article/details/101052036），我们最后留了个实例，就是生成这样的json字符串：

{
    "first fruit":
    {
        "describe":"an apple",
        "icon":"appleIcon",
        "name":"apple"
    },
    "second fruit":
    {
        "describe":"an orange",
        "icon":"orangeIcon",
        "name":"orange"
    },
    "three fruit array":
    [
        "eat 0",
        "eat 1",
        "eat 2",
        "eat 3",
        "eat 4"
    ]
}

这样嵌套的格式，就需要用到结构体来处理。

package main

import (
	"fmt"
	"encoding/json"
	"os"
)

type Fruit struct {
	Describe string `json:"describe"`
	Icon     string `json:"icon"`
	Name     string `json:"name"`
}

type FruitGroup struct {
	FirstFruit  *Fruit `json:"first fruit"`  //指针，指向引用对象；如果不用指针，只是值复制
	SecondFruit *Fruit `json:"second fruit"` //指针，指向引用对象；如果不用指针，只是值复制
	THreeFruitArray []string `json:"three fruit array"`
}

func main() {
	firstFruit := new(Fruit)  //指针
	firstFruit.Describe = "an apple"
	firstFruit.Icon = "appleIcon"
	firstFruit.Name = "apple"

	secondFruit := new(Fruit) //指针
	secondFruit.Describe = "an orange"
	secondFruit.Icon = "appleIcon"
	secondFruit.Name = "orange"

	fruitGroup := FruitGroup{}
	fruitGroup.THreeFruitArray = []string{"eat 0","eat 1","eat 2","eat 3"}
	fruitGroup.FirstFruit = firstFruit //指针，避免了拷贝
	fruitGroup.SecondFruit = secondFruit //指针，避免了拷贝

	//方式一
	// b, err := json.Marshal(fruitGroup)
	// if err != nil {
	//     fmt.Println("error:", err)
	// }
	// fmt.Println(string(b))
	//输出结果：(输出的结果没有换行，这里人为加上换行是为了方便查看)
	//{"first fruit":{"describe":"an apple","icon":"appleIcon","name":"apple"},
	//"second fruit":{"describe":"an orange","icon":"appleIcon","name":"orange"},
	//"three fruit array":["eat 0","eat 1","eat 2","eat 3"]}
	
	//方式二
	//第二个参数表示的添加的前缀，第三个参数表示缩进四个空格；这两个参数你都可以修改为其他字符串
	output, err := json.MarshalIndent(fruitGroup, "", "    ")
	if err != nil {
		fmt.Printf("error: %v\n", err)
	}
	os.Stdout.Write(output)
}

输出结果：

{
    "first fruit": {
        "describe": "an apple",
        "icon": "appleIcon",
        "name": "apple"
    },
    "second fruit": {
        "describe": "an orange",
        "icon": "appleIcon",
        "name": "orange"
    },
    "three fruit array": [
        "eat 0",
        "eat 1",
        "eat 2",
        "eat 3"
    ]
}

参考：
golang中json与struct中tag
GO :json解析及生成json
Go – 在Go语言中使用JSON struct