Update download system

增加证书认证方法

Assets/YooAsset/Runtime/DownloadSystem/DownloadSystem.cs

@@ -2,6 +2,7 @@
 using System.IO;
 using System.Collections;
 using System.Collections.Generic;
+using UnityEngine.Networking;
 
 namespace YooAsset
 {
@@ -15,6 +16,12 @@ namespace YooAsset
 		private static readonly Dictionary<string, DownloaderBase> _downloaderDic = new Dictionary<string, DownloaderBase>();
 		private static readonly List<string> _removeList = new List<string>(100);
 
+
+		/// <summary>
+		/// 自定义的证书认证实例
+		/// </summary>
+		public static CertificateHandler CertificateHandlerInstance;
+
 		/// <summary>
 		/// 启用断点续传功能文件的最小字节数
 		/// </summary>

Assets/YooAsset/Runtime/DownloadSystem/Downloader/FileDownloader.cs

@@ -89,6 +89,12 @@ namespace YooAsset
 					_downloadHandle = handler;
 #endif
 
+					if (DownloadSystem.CertificateHandlerInstance != null)
+					{
+						_webRequest.certificateHandler = DownloadSystem.CertificateHandlerInstance;
+						_webRequest.disposeCertificateHandlerOnDispose = false;
+					}
+
 					_webRequest.downloadHandler = handler;
 					_webRequest.disposeDownloadHandlerOnDispose = true;
 					if (fileLength > 0)

Assets/YooAsset/Runtime/YooAssets.cs

@@ -161,7 +161,16 @@ namespace YooAsset
 		{
 			DownloadSystem.ClearFileResponseCodes = codes;
 		}
-		
+
+		/// <summary>
+		/// 设置下载系统参数，自定义的证书认证实例
+		/// </summary>
+		/// <param name="instance"></param>
+		public static void SetDownloadSystemCertificateHandler(UnityEngine.Networking.CertificateHandler instance)
+		{
+			DownloadSystem.CertificateHandlerInstance = instance;
+		}
+
 		/// <summary>
 		/// 设置异步系统参数，每帧执行消耗的最大时间切片（单位：毫秒）
 		/// </summary>