/// <summary>
    /// 表(biao)示(shi)用(yong)于方法緩存功(gong)能的攔(lan)截行為。
    /// </summary>
    public class CachingBehavior : IInterceptionBehavior
    {
        /// <summary>
        /// 緩(huan)存(cun)項(xiang)目名稱(cheng)，每個項(xiang)目有自己(ji)的名稱(cheng)
        /// 避免緩(huan)存鍵名(ming)重復
        /// </summary>
        static readonly string cacheProjectName = System.Configuration.ConfigurationManager.AppSettings["CacheProjectName"] ?? "DataSetCache";


        #region Private Methods
        /// <summary>
        /// 根據指定的<see cref="CachingAttribute"/>以及<see cref="IMethodInvocation"/>實例(li)，
        /// 獲取與某一特(te)定參數值相關的鍵名。
        /// </summary>
        /// <param name="cachingAttribute"><see cref="CachingAttribute"/>實例。</param>
        /// <param name="input"><see cref="IMethodInvocation"/>實例。</param>
        /// <returns>與某一特定參數值相關的鍵名。</returns>
        private string GetValueKey(CachingAttribute cachingAttribute, IMethodInvocation input)
        {
            switch (cachingAttribute.Method)
            {
                // 如果(guo)是Remove，則(ze)不存在(zai)特定(ding)值鍵名，所有的(de)以(yi)該方法名稱(cheng)相(xiang)關的(de)緩存都需要(yao)清(qing)除
                case CachingMethod.Remove:
                    return null;
                // 如果是Get或者Put，則需要產生一(yi)個針對(dui)特定(ding)參數值(zhi)的鍵名
                case CachingMethod.Get:
                case CachingMethod.Put:
                    if (input.Arguments != null &&
                        input.Arguments.Count > 0)
                    {
                        var sb = new StringBuilder();
                        for (int i = 0; i < input.Arguments.Count; i++)
                        {
                            if (input.Arguments[i].GetType().BaseType == typeof(LambdaExpression))//lambda處理
                            {
                                var exp = input.Arguments[i] as LambdaExpression;
                                var arr = ((System.Runtime.CompilerServices.Closure)(((System.Delegate)(Expression.Lambda(exp).Compile().DynamicInvoke())).Target)).Constants;

                                Type t = arr[0].GetType();
                                string result = "";

                                foreach (var member in t.GetFields())
                                {
                                    result += member.Name + "_" + t.GetField(member.Name).GetValue(arr[0]) + "_";
                                }
                                result = result.Remove(result.Length - 1);
                                sb.Append(result.ToString());
                            }
                            else if (input.Arguments[i].GetType() != typeof(string)//類和結構體(ti)處理
                                && input.Arguments[i].GetType().BaseType.IsClass)
                            {
                                var obj = input.Arguments[i];
                                Type t = obj.GetType();
                                string result = "";

                                foreach (var member in t.GetProperties())//公開屬性
                                {
                                    result += member.Name + "_" + t.GetProperty(member.Name).GetValue(obj) + "_";
                                }
                                foreach (var member in t.GetFields(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance))//私有和公用字段
                                {
                                    result += member.Name + "_" + t.GetField(member.Name, BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance).GetValue(obj) + "_";
                                }
                                result = result.Remove(result.Length - 1);
                                sb.Append(result.ToString());
                            }
                            else//簡(jian)單值類型處理
                            {
                                sb.Append(input.Arguments[i].ToString());
                            }

                            if (i != input.Arguments.Count - 1)
                                sb.Append("_");
                        }
                        return sb.ToString();
                    }
                    else
                        return "NULL";
                default:
                    throw new InvalidOperationException("無效的緩存方式。");
            }
        }
        #endregion

        #region IInterceptionBehavior Members
        /// <summary>
        /// 獲取當(dang)前行為需要攔截的對象類(lei)型接(jie)口(kou)。
        /// </summary>
        /// <returns>所有需(xu)要攔截的對象類型接口。</returns>
        public IEnumerable<Type> GetRequiredInterfaces()
        {
            return Type.EmptyTypes;
        }

        /// <summary>
        /// 通過實現此方法來攔截(jie)調用并執行(xing)所需的(de)攔截(jie)行(xing)為。
        /// </summary>
        /// <param name="input">調用攔截目(mu)標時的輸入信息。</param>
        /// <param name="getNext">通過行(xing)為鏈來獲(huo)取下一(yi)個攔截行(xing)為的(de)委(wei)托。</param>
        /// <returns>從(cong)攔截(jie)目標獲得的返回信息。</returns>
        public IMethodReturn Invoke(IMethodInvocation input, GetNextInterceptionBehaviorDelegate getNext)
        {

            var method = input.MethodBase;
            //鍵值前綴
            string prefix = cacheProjectName + "_" + input.Target.ToString() + "_";
            //鍵名(ming)，在put和get時(shi)使用
            var key = prefix + method.Name;

            if (method.IsDefined(typeof(CachingAttribute), false))
            {
                var cachingAttribute = (CachingAttribute)method.GetCustomAttributes(typeof(CachingAttribute), false)[0];
                var valKey = GetValueKey(cachingAttribute, input);
                switch (cachingAttribute.Method)
                {
                    case CachingMethod.Get:
                        try
                        {
                            if (CacheManager.Instance.Exists(key, valKey))
                            {
                                var obj = CacheManager.Instance.Get(key, valKey);
                                var arguments = new object[input.Arguments.Count];
                                input.Arguments.CopyTo(arguments, 0);
                                return new VirtualMethodReturn(input, obj, arguments);
                            }
                            else
                            {
                                var methodReturn = getNext().Invoke(input, getNext);
                                CacheManager.Instance.Add(key, valKey, methodReturn.ReturnValue);
                                return methodReturn;
                            }
                        }
                        catch (Exception ex)
                        {
                            return new VirtualMethodReturn(input, ex);
                        }
                    case CachingMethod.Put:
                        try
                        {
                            var methodReturn = getNext().Invoke(input, getNext);
                            if (CacheManager.Instance.Exists(key))
                            {
                                if (cachingAttribute.Force)
                                {
                                    CacheManager.Instance.Remove(key);
                                    CacheManager.Instance.Add(key, valKey, methodReturn.ReturnValue);
                                }
                                else
                                    CacheManager.Instance.Put(key, valKey, methodReturn.ReturnValue);
                            }
                            else
                                CacheManager.Instance.Add(key, valKey, methodReturn.ReturnValue);
                            return methodReturn;
                        }
                        catch (Exception ex)
                        {
                            return new VirtualMethodReturn(input, ex);
                        }
                    case CachingMethod.Remove:
                        try
                        {
                            var removeKeys = cachingAttribute.CorrespondingMethodNames;
                            foreach (var removeKey in removeKeys)
                            {
                                string delKey = prefix + removeKey;
                                if (CacheManager.Instance.Exists(delKey))
                                    CacheManager.Instance.Remove(delKey);
                            }
                            var methodReturn = getNext().Invoke(input, getNext);
                            return methodReturn;
                        }
                        catch (Exception ex)
                        {
                            return new VirtualMethodReturn(input, ex);
                        }
                    default: break;
                }
            }

            return getNext().Invoke(input, getNext);
        }

        /// <summary>
        /// 獲(huo)取一個<see cref="Boolean"/>值，該值表示當前攔截行為被調用時，是否真的需要執行
        /// 某些操作。
        /// </summary>
        public bool WillExecute
        {
            get { return true; }
        }

        #endregion
    }