C# Unity 将数据从 JSON 读取到对象数组中

Question

我正在尝试从 JSON 文件中读取一系列项目到 Object 数组中。 不幸的是，它返回为 null。

很像这个问题Unity C# JsonUtility is not serializing a list

所以在我的特殊情况下，我有该项目的类：

[Serializable]
public class StateData
{
    public string name;
    public string location;
    public string gameText;
}

项目集合的类：

[Serializable]
public class StateDataCollection
{
    public List<StateData> stateDatas = new List<StateData>();
}

以及调用它的类：

public class JSONReader : MonoBehaviour
{
    private const string Path = @"S:\repos\myProject\Assets\gameText\";

    void Start()
    {
        string json = File.ReadAllText(Path + "StateData.json");
        StateDataCollection stateDataCollection = new StateDataCollection();
        stateDataCollection = JsonUtility.FromJson<StateDataCollection>(json);
    }
}

终于有了json

{
"StateData":[
{
"name": "name", 
"location":"location",
"gameText" : "gameText"},
{
"name": "name", 
"location":"location",
"gameText" : "gameText"},
{
"name": "name", 
"location":"location",
"gameText" : "gameText"
}]
}

对象返回为空。 文件读取正常。

有什么想法是失败的吗？ 泰！

Answer 1

我会先检查几件事：

• 检查文件是否确实存在。只需使用一个小的Debug.Log(File.Exists(path))。
• 尝试其他路径 -> 保存类似：Application.persistentDataPath。在 Windows 上，这将为您提供如下内容：%userprofile%\AppData\Local\Packages\LocalState。这可确保您能够读取/写入文件。
• 用实际数据填写List，以便区分保存的列表和默认列表。

编辑 1：
我刚刚复制了您的代码并对其进行了一些调整。它并不完美，但它肯定对我有用。

状态数据：

using System;

[Serializable]
public struct StateData
{
    public string m_Name;
    public string m_Location;
    public string m_GameText;

    public StateData(string name, string location, string gameText)
    {
        m_Name = name;
        m_Location = location;
        m_GameText = gameText;
    }
}

StateDataCollection：

using System;
using System.Collections.Generic;

[Serializable]
public class StateDataCollection
{
    public List<StateData> m_StateData;

    public StateDataCollection() => m_StateData = new List<StateData>();
}

JSONReader：

using System.IO;
using UnityEngine;

public class JSONReader : MonoBehaviour
{
    private const string FILENAME = "StateData.json";

    private string m_path;
    public string FilePath {
        get => m_path;
        set => m_path = value;
    }

    void Start()
    {
        FilePath = Path.Combine(Application.persistentDataPath, FILENAME);
        Debug.Log(FilePath);// delete me

        StateDataCollection stateDataCollection = new StateDataCollection();
        stateDataCollection.m_StateData.Add(new StateData("Peter", "X", "123"));
        stateDataCollection.m_StateData.Add(new StateData("Annie", "Y", "42"));
        stateDataCollection.m_StateData.Add(new StateData("TheGuyFromTheSupermarket", "Supermarket", "666"));


        SaveStateDataCollectionToPath(FilePath, stateDataCollection);

        LoadStateDataCollectionFromPath(FilePath);
    }

    private void SaveStateDataCollectionToPath(string path, StateDataCollection stateDataCollection)
    {
        // ToDo: some checks on path and stateDataCollection
        string json = JsonUtility.ToJson(stateDataCollection, true);// prettyPrint active

        File.WriteAllText(path, json);
    }

    private void LoadStateDataCollectionFromPath(string path)
    {
        if(File.Exists(path)) {
            Debug.Log($"File exists at: {path}");// delete me

            string json = File.ReadAllText(path);
            StateDataCollection stateDataCollection = JsonUtility.FromJson<StateDataCollection>(json);

            // delete me
            Debug.Log($"StateDataCollection count: { stateDataCollection.m_StateData.Count}");
            int i = 1;
            stateDataCollection.m_StateData.ForEach(o => {
                Debug.Log(
                    $"Item Nr.: {i}\n" +
                    $"Name: {o.m_Name}\n" +
                    $"Location: {o.m_Location}\n" +
                    $"GameText: {o.m_GameText}\n\n");
                ++i;
            });
        }
    }
}

我还添加了几个Debug.Log()s 用于测试。
用法：
在SaveStateDataCollectionToPath(FilePath, stateDataCollection); 活动的情况下运行一次，在没有它的情况下运行一次。 控制台应显示 3 个项目。
编辑 2：
我认为您的问题可能是违反命名约定。 File 需要using System.IO;，在File 旁边还包含Path。不幸的是，您还将const string 命名为“路径”。