增加 ApiContext.Current，用于获取当前上下文

Apewer/Web/ApiContext.cs

@@ -1,9 +1,6 @@
-using Apewer.Network;
-using System;
-using System.Collections.Generic;
-using System.Diagnostics;
+using System;
 using System.Reflection;
-using System.Text;
+using System.Threading;
 
 namespace Apewer.Web
 {
@@ -69,6 +66,36 @@ namespace Apewer.Web
 
         #endregion
 
+        #region Current
+
+#if NET461_OR_GREATER || NETSTANDARD || NETCOREAPP
+        static AsyncLocal<ApiContext> _current = new AsyncLocal<ApiContext>();
+#endif
+
+        static void SetCurrent(ApiContext context)
+        {
+#if NET461_OR_GREATER || NETSTANDARD || NETCOREAPP
+            _current.Value = context;
+#else
+            System.Runtime.Remoting.Messaging.CallContext.LogicalSetData("ApiContext", context);
+#endif
+        }
+
+        static ApiContext GetCurrent()
+        {
+#if NET461_OR_GREATER || NETSTANDARD || NETCOREAPP
+            if (_current == null) return null;
+            return _current.Value;
+#else
+            return System.Runtime.Remoting.Messaging.CallContext.LogicalGetData("ApiContext") as ApiContext;
+#endif
+        }
+
+        /// <summary>获取当前的 <see cref="ApiContext" /> 实例。</summary>
+        public static ApiContext Current { get => GetCurrent(); }
+
+        #endregion
+
         internal ApiContext(ApiInvoker invoker, ApiProvider provider, ApiEntries entries)
         {
             if (invoker == null) throw new ArgumentNullException(nameof(invoker));
@@ -78,9 +105,9 @@ namespace Apewer.Web
             _invoker = invoker;
             _provider = provider;
             _entries = entries;
-
             _options = invoker.Options ?? new ApiOptions();
 
+            SetCurrent(this);
         }
 
         /// <summary>自定义数据。若此自定义数据实现了 <see cref="IDisposable" />，将会与 Context 一起自动释放。</summary>