Unity 序列化与反序列化，多次使用AssetDatabase.CreateAsset(asset, path)创建同一个资源，场景引用资源的位置出现 missing

• 使用 ScriptableObject 保存到硬盘后在编辑器中可以二次编辑

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEditor;
using System.IO;

public class TestScriptableObject : Editor {

    [MenuItem("Tools/Serialize")]
    private static void Serialize () {
        Rect rect = ScriptableObject.CreateInstance<Rect>();
        rect.width = 10;
        rect.height = 20;

        // *注意 AssetDatabase.CreateAsset 方法使用的是相对路径
        string path = "Assets/Data";
        if (!Directory.Exists(path)) {
            Directory.CreateDirectory(path);
        }

        // Assets/Data/Rect.asset
        path += $"/Rect.asset";
        AssetDatabase.CreateAsset(rect, path);
    }

    [MenuItem("Tools/Deserialize")]
    private static void Deserialize () {
        Rect rect = AssetDatabase.LoadAssetAtPath<Rect>("Assets/Data/Rect.asset");
        Debug.Log(rect.width);  // 10
        Debug.Log(rect.height); // 20
    }


    public class Rect : ScriptableObject {
        public int width;
        public int height;
    }
}

• 二进制序列化与反序列化

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEditor;
using System.IO;
using System.Runtime.Serialization.Formatters.Binary;

public class TestBinary : Editor {

    [MenuItem("Tools/BinarySerialize")]
    private static void BinarySerialize () {
        Rect rect = new Rect();
        rect.width = 10;
        rect.height = 20;

        string path = Application.dataPath + "/Data/Rect.bytes";
        FileStream fileStream = new FileStream(path, FileMode.Create, FileAccess.Write, FileShare.ReadWrite);
        BinaryFormatter binaryFormatter = new BinaryFormatter();
        binaryFormatter.Serialize(fileStream,rect);
        fileStream.Close();

        AssetDatabase.Refresh(); // 保存到 Assets 文件夹下需要刷新才能看到
    }

    [MenuItem("Tools/BinaryDeserialize")]
    private static void BinaryDeserialize () {
        // 非 Assets 文件夹下时，使用 byte[] bytes = File.ReadAllBytes(path);
        TextAsset textAsset = AssetDatabase.LoadAssetAtPath<TextAsset>("Assets/Data/Rect.bytes");

        MemoryStream memoryStream = new MemoryStream(textAsset.bytes);
        BinaryFormatter binaryFormatter = new BinaryFormatter();

        Rect rect = (Rect)binaryFormatter.Deserialize(memoryStream);
        memoryStream.Close();

        Debug.Log(rect.width);  // 10
        Debug.Log(rect.height); // 20
    }

    // * 注意必须标记可序列化
    [System.Serializable]
    public class Rect{
        public int width;
        public int height;
    }
}

• XML 序列化与反序列化

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEditor;
using System.IO;
using System.Xml.Serialization;

public class TestXml : Editor {

    [MenuItem("Tools/XmlSerialize")]
    private static void XmlSerialize () {
        Rect rect = new Rect();
        rect.width = 10;
        rect.height = 20;

        string path = Application.dataPath + "/Data/Rect.xml";
        FileStream fileStream = new FileStream(path, FileMode.Create, FileAccess.Write, FileShare.ReadWrite);
        StreamWriter streamWriter = new StreamWriter(fileStream, System.Text.Encoding.UTF8);
        XmlSerializer xmlSerializer = new XmlSerializer(rect.GetType());
        xmlSerializer.Serialize(streamWriter, rect);
        streamWriter.Close();
        fileStream.Close();

        AssetDatabase.Refresh(); // 保存到 Assets 文件夹下需要刷新才能看到
    }

    [MenuItem("Tools/XmlDeserialize")]
    private static void XmlDeserialize () {
        string path = Application.dataPath + "/Data/Rect.xml";
        FileStream fileStream = new FileStream(path, FileMode.Open, FileAccess.ReadWrite, FileShare.ReadWrite);
        XmlSerializer xmlSerializer = new XmlSerializer(typeof(Rect));
        Rect rect = (Rect)xmlSerializer.Deserialize(fileStream);
        fileStream.Close();

        Debug.Log(rect.width);  // 10
        Debug.Log(rect.height); // 20
    }

    // * 注意必须标记可序列化
    [System.Serializable]
    public class Rect {
        public int width;
        public int height;
    }
}

• JSON 序列化与反序列化

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEditor;
using System.IO;

public class TestJson : Editor {

    [MenuItem("Tools/JsonSerialize")]
    private static void JsonSerialize () {
        Rect rect = new Rect();
        rect.width = 10;
        rect.height = 20;

        string jsonString = JsonUtility.ToJson(rect);
        string path = Application.dataPath + "/Data/Rect.json";
        File.WriteAllText(path, jsonString);

        AssetDatabase.Refresh(); // 保存到 Assets 文件夹下需要刷新才能看到
    }

    [MenuItem("Tools/JsonDeserialize")]
    private static void JsonDeserialize () {
        string path = Application.dataPath + "/Data/Rect.json";
        StreamReader streamReader = File.OpenText(path);
        string jsonString = streamReader.ReadToEnd();
        streamReader.Close();

        Rect rect = JsonUtility.FromJson<Rect>(jsonString);
        Debug.Log(rect.width);  // 10
        Debug.Log(rect.height); // 20
    }

    public class Rect {
        public int width;
        public int height;
    }
}

---

• 注意：不能使用父类来代替子类进行序列化

#if UNITY_EDITOR

using System.Collections.Generic;
using UnityEditor;
using UnityEngine;


public class RefData : ScriptableObject {
    public Foo[] foos;
}

[System.Serializable]
public class Foo {
    public int a;
    public Vector2 b;
}

[System.Serializable]
public class Goo : Foo {
    public string c;
}

public class EditorTest : Editor {

    [MenuItem("Tools/Serialize")]
    private static void Serialize() {
        var refData = ScriptableObject.CreateInstance<RefData>();
        refData.foos = new Foo[3];
        refData.foos[0] = new Foo { a = 0, b = Vector2.up };
        refData.foos[1] = new Foo { a = 1, b = Vector2.down };
        refData.foos[2] = new Goo { a = 2, b = Vector2.left, c = "c" };

        AssetDatabase.CreateAsset(refData, "Assets/RefData.asset");
    }

    [MenuItem("Tools/Deserialize")]
    private static void Deserialize() {
        RefData refData = AssetDatabase.LoadAssetAtPath<RefData>("Assets/RefData.asset");
        // 当重载加载当前程序集时（重新编译脚本或重启unity），输出 false
        Debug.Log(refData.foos[2] is Goo);
    }
}
#endif

---

• 重复使用 AssetDatabase.CreateAsset(asset, path) 创建同一个资源时，场景中存在引用该资源的的位置出现 missing 丢失引用，所有代码如下：
  PlayerData .cs

using UnityEngine;
public class PlayerData : ScriptableObject {
    public string id;
}

Player.cs

using UnityEngine;
public class Player : MonoBehaviour {
    public PlayerData data;
}

TestCreateAsset.cs 放置在 Editor 文件夹

using UnityEditor;
using UnityEngine;
public class TestCreateAsset : Editor {
    [MenuItem("Tools/TestCreateAsset")]
    private static void Test() {
        PlayerData playerData = ScriptableObject.CreateInstance<PlayerData>();
        playerData.id = "aa";

        const string path = "Assets/playerData.asset";
        AssetDatabase.CreateAsset(playerData, path);
        AssetDatabase.Refresh();
    }
}

注意：不能多次使用AssetDatabase.CreateAsset(asset, path)创建同一个资源。即使资源没发生更改，否则就会出现 missing
正确做法如下：
TestCreateAsset.cs

using System.IO;
using UnityEditor;
using UnityEngine;
public class TestCreateAsset : Editor {
    [MenuItem("Tools/TestCreateAsset")]
    private static void Test() {
        const string path = "Assets/playerData.asset";

        PlayerData playerData;
        bool isExists = File.Exists(path);

        if (isExists) {
            playerData = AssetDatabase.LoadAssetAtPath<PlayerData>(path);
            playerData.id = "bb";
            EditorUtility.SetDirty(playerData);
            AssetDatabase.SaveAssetIfDirty(playerData);
        } else {
            playerData = ScriptableObject.CreateInstance<PlayerData>();
            playerData.id = "aa";
            AssetDatabase.CreateAsset(playerData, path);
        }

        AssetDatabase.Refresh();
    }
}