使用场景

最近在做资源管理模块时，关于资源引用这方面的问题，并不想直接引用某一个asset ，比如Prefab、或者sprite、material等资源，当然可以由资源管理模块统一管理，然后对业务层提供获取的接口。由业务层传入文件名、或者AssetBundle Name、path之类的数据，资源管理模块内加载出来然后返回。结合ObjectFiled这个编辑器类来介绍，我们拖入某一个asset，然后序列化存储其guid和asset path，表面上看起来是引用了该asset，实际上只是存住了guid和path（用于load，结合资源管理模块而定），guid用于绝对指向asset资源，就算路径更改，也不怕引用丢失。

ObjectField介绍

https://docs.unity3d.com/2017.2/Documentation/ScriptReference/EditorGUI.ObjectField.html

FileField实现

private string[] FileField(Rect position, string label, string guid,Type type)
	{
		string[] guidPath = new string[2];//存储guid和path，这里的path是assetPath，实际存储起来需要做一步处理，处理成资源管理模块能load的path或者别的数据
		string path = AssetDatabase.GUIDToAssetPath(guid);
		UnityEngine.Object file = AssetDatabase.LoadAssetAtPath(path,type);
		EditorGUI.BeginChangeCheck();
		{
			//编辑器上显示的是ObjectField绘制出来的                                                                                  
			file = EditorGUI.ObjectField(position, label, file, type, false);
		}

		if (EditorGUI.EndChangeCheck())
		{
			path = AssetDatabase.GetAssetPath(file);
			guid = AssetDatabase.AssetPathToGUID(path);
		}

		guidPath[0] = guid;
		guidPath[1] = path;
		return guidPath;
	}

不算完整的代码：

using UnityEditor;
using UnityEngine;
using System;
using System.IO;
using IdleGames.Core.AssetManagement;

[CustomPropertyDrawer(typeof(WeakReferenceAttribute), true)]
public class WeakReferenceBaseDrawer : PropertyDrawer
{
	public override void OnGUI(Rect position, SerializedProperty property, GUIContent label)
	{
		WeakReferenceAttribute attribute = (WeakReferenceAttribute)base.attribute;
		Type referenceType = typeof(GameObject);
		if (attribute != null)
		{
			referenceType = attribute.AssetType;
		}
		
		SerializedProperty guidProperty = property.FindPropertyRelative(\"_guid\");
		SerializedProperty pathProperty = property.FindPropertyRelative(\"_path\");
		Rect guidRect = position;
		
		string[] guidPath = FileField(guidRect, property.displayName, guidProperty.stringValue,referenceType);
		guidProperty.stringValue = guidPath[0];
		//这里演示的是把path存成了Resources文件夹下的path
		if (string.IsNullOrEmpty(guidPath[1]) == false && guidPath[1].Contains(\"Resources/\"))
		{
			int index = guidPath[1].LastIndexOf(\"Resources/\") + \"Resources/\".Length;
			string path = guidPath[1].Substring(index);
			path = path.Remove(path.LastIndexOf(\".\"));
			pathProperty.stringValue = path;
		}
		property.serializedObject.ApplyModifiedProperties();
	}
	
	private string[] FileField(Rect position, string label, string guid,Type type)
	{
		string[] guidPath = new string[2];
		string path = AssetDatabase.GUIDToAssetPath(guid);
		UnityEngine.Object file = AssetDatabase.LoadAssetAtPath(path,type);
		EditorGUI.BeginChangeCheck();
		{                                                                                  
			file = EditorGUI.ObjectField(position, label, file, type, false);
		}

		if (EditorGUI.EndChangeCheck())
		{
			path = AssetDatabase.GetAssetPath(file);
			guid = AssetDatabase.AssetPathToGUID(path);
		}

		guidPath[0] = guid;
		guidPath[1] = path;
		return guidPath;
	}
}

上述代码仅供参考，拖入的object与实际序列化存储的不是同一个东西时，可以用上述类似的思路

以上知识分享，如有错误，欢迎指出，共同学习，共同进步。