using System;using System.Runtime.InteropServices;namespace Common{  public  class IECache    {        [DllImport("Wininet.dll", SetLastError = true, CharSet = CharSet.Auto)]        public static extern Boolean GetUrlCacheEntryInfo(String lpxaUrlName, IntPtr lpCacheEntryInfo, ref int lpdwCacheEntryInfoBufferSize);        const int ERROR_FILE_NOT_FOUND = 0x2;        struct LPINTERNET_CACHE_ENTRY_INFO        {            public int dwStructSize;            IntPtr lpszSourceUrlName;            public IntPtr lpszLocalFileName;            int CacheEntryType;            int dwUseCount;            int dwHitRate;            int dwSizeLow;            int dwSizeHigh;            FILETIME LastModifiedTime;            FILETIME Expiretime;            FILETIME LastAccessTime;            FILETIME LastSyncTime;            IntPtr lpHeaderInfo;            int dwheaderInfoSize;            IntPtr lpszFileExtension;            int dwEemptDelta;        }        // 返回 指定URL文件的缓存在本地文件系统中的路径        public string GetPathForCachedFile(string fileUrl)        {            int cacheEntryInfoBufferSize = 0;            IntPtr cacheEntryInfoBuffer = IntPtr.Zero;            int lastError; Boolean result;            try            {                result = GetUrlCacheEntryInfo(fileUrl, IntPtr.Zero, ref cacheEntryInfoBufferSize);                lastError = Marshal.GetLastWin32Error();                if (result == false)                {                    if (lastError == ERROR_FILE_NOT_FOUND)                         return null;                }                cacheEntryInfoBuffer = Marshal.AllocHGlobal(cacheEntryInfoBufferSize);                result = GetUrlCacheEntryInfo(fileUrl, cacheEntryInfoBuffer, ref cacheEntryInfoBufferSize);                lastError = Marshal.GetLastWin32Error();                if (result == true)                {                    Object strObj = Marshal.PtrToStructure(cacheEntryInfoBuffer, typeof(LPINTERNET_CACHE_ENTRY_INFO));                    LPINTERNET_CACHE_ENTRY_INFO internetCacheEntry = (LPINTERNET_CACHE_ENTRY_INFO)strObj;                    String localFileName = Marshal.PtrToStringAuto(internetCacheEntry.lpszLocalFileName); return localFileName;                }                else                     return null;// file not found            }            finally            {                if (!cacheEntryInfoBuffer.Equals(IntPtr.Zero))                     Marshal.FreeHGlobal(cacheEntryInfoBuffer);            }        }    }}