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CloudBuilder/CloudBuilder.Core/Extensions/CustomAttributeExtensions.cs

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+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace CloudBuilder.Core.Extensions
+{
+    using System;
+    using System.Collections.Concurrent;
+    using System.Reflection;
+
+    public static class CustomAttributeExtensions
+    {
+        /// <summary>
+        /// Cache Data
+        /// </summary>
+        private static readonly ConcurrentDictionary<string, object> Cache = new ConcurrentDictionary<string, object>();
+
+        /// <summary>
+        /// 获取CustomAttribute Value
+        /// </summary>
+        /// <typeparam name="TAttribute">Attribute的子类型</typeparam>
+        /// <typeparam name="TReturn">TReturn的子类型</typeparam>
+        /// <param name="sourceType">头部标有CustomAttribute类的类型</param>
+        /// <param name="attributeValueAction">取Attribute具体哪个属性值的匿名函数</param>
+        /// <returns>返回Attribute的值，没有则返回null</returns>
+        public static TReturn GetCustomAttributeValue<TAttribute, TReturn>(this Type sourceType, Func<TAttribute, TReturn> attributeValueAction)
+            where TAttribute : Attribute
+        {
+            return _getAttributeValue(sourceType, attributeValueAction, null);
+        }
+
+        /// <summary>
+        /// 获取CustomAttribute Value
+        /// </summary>
+        /// <typeparam name="TAttribute">Attribute的子类型</typeparam>
+        /// <typeparam name="TReturn">TReturn的子类型</typeparam>
+        /// <param name="sourceType">头部标有CustomAttribute类的类型</param>
+        /// <param name="attributeValueAction">取Attribute具体哪个属性值的匿名函数</param>
+        /// <param name="propertyName">field name或property name</param>
+        /// <returns>返回Attribute的值，没有则返回null</returns>
+        public static TReturn GetCustomAttributeValue<TAttribute, TReturn>(this Type sourceType, Func<TAttribute, TReturn> attributeValueAction, string propertyName)
+            where TAttribute : Attribute
+        {
+            return _getAttributeValue(sourceType, attributeValueAction, propertyName);
+        }
+
+        #region private methods
+
+        private static TReturn _getAttributeValue<TAttribute, TReturn>(Type sourceType, Func<TAttribute, TReturn> attributeFunc, string propertyName)
+            where TAttribute : Attribute
+        {
+            var cacheKey = BuildKey<TAttribute>(sourceType, propertyName);
+            var value = Cache.GetOrAdd(cacheKey, k => GetValue(sourceType, attributeFunc, propertyName));
+            if (value is TReturn) return (TReturn)Cache[cacheKey];
+            return default(TReturn);
+        }
+
+        private static string BuildKey<TAttribute>(Type type, string propertyName) where TAttribute : Attribute
+        {
+            var attributeName = typeof(TAttribute).FullName;
+            if (string.IsNullOrEmpty(propertyName))
+            {
+                return type.FullName + "." + attributeName;
+            }
+
+            return type.FullName + "." + propertyName + "." + attributeName;
+        }
+
+        private static TReturn GetValue<TAttribute, TReturn>(this Type type, Func<TAttribute, TReturn> attributeValueAction, string name)
+            where TAttribute : Attribute
+        {
+            TAttribute attribute = default(TAttribute);
+            if (string.IsNullOrEmpty(name))
+            {
+                attribute = type.GetCustomAttribute<TAttribute>(false);
+            }
+            else
+            {
+                var propertyInfo = type.GetProperty(name);
+                if (propertyInfo != null)
+                {
+                    attribute = propertyInfo.GetCustomAttribute<TAttribute>(false);
+                }
+                else
+                {
+                    var fieldInfo = type.GetField(name);
+                    if (fieldInfo != null)
+                    {
+                        attribute = fieldInfo.GetCustomAttribute<TAttribute>(false);
+                    }
+                    else
+                    {
+                        var methodInfo = type.GetMethod(name);
+                        if (methodInfo != null)
+                        {
+                            attribute = methodInfo.GetCustomAttribute<TAttribute>(false);
+                        }
+                    }
+                }
+            }
+
+            return attribute == null ? default(TReturn) : attributeValueAction(attribute);
+        }
+
+        #endregion
+    }
+}