C# 如何从嵌套类或结构以json格式编写

将嵌套json文件的结构作为嵌套类，当我写入json时，json总是空的

public class Class1
{
    public int level;
    public float timeElapsed;
    public string playerName;
    public Class2 subClass;


}

public class Class2
{
    public int age;
}

---

我得到{“等级”：1，“时间流逝”：47.5，“玩家名称”：“弗朗西斯”}，年龄在哪里

using System;
using UnityEngine;

public class Example : MonoBehaviour
{
    private void Start()
    {
        Class2 class2 = new Class2();
        class2.age = 99;

        Class1 myObject = new Class1();
        myObject.level = 1;
        myObject.timeElapsed = 47.5f;
        myObject.playerName = "Francis";
        myObject.subClass = class2;

        var jsonString = JsonUtility.ToJson(myObject);
        print(jsonString);
    }
}

[Serializable]
public class Class1
{
    public int level;
    public float timeElapsed;
    public string playerName;
    public Class2 subClass;
}

[Serializable]
public class Class2
{
    public int age;
}

---

结果是{“level”：1，“timeappeased”：47.5，“playerName”：“Francis”，“subClass”：{“age”：99}

我不做Unity，但我发现这表明类需要

[Serializable]

属性。

using System;
using UnityEngine;

public class Example : MonoBehaviour
{
    private void Start()
    {
        Class2 class2 = new Class2();
        class2.age = 99;

        Class1 myObject = new Class1();
        myObject.level = 1;
        myObject.timeElapsed = 47.5f;
        myObject.playerName = "Francis";
        myObject.subClass = class2;

        var jsonString = JsonUtility.ToJson(myObject);
        print(jsonString);
    }
}

[Serializable]
public class Class1
{
    public int level;
    public float timeElapsed;
    public string playerName;
    public Class2 subClass;
}

[Serializable]
public class Class2
{
    public int age;
}