Wininetdll函数库：根据url获取缓存文件

using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;
namespace ConsoleApplication34
{
class Program
{
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
public struct internet_cache_entry_info
{
public int dwstructsize;
public IntPtr lpszsourceurlname;
public IntPtr lpszlocalfilename;
public int cacheentrytype;
public int dwusecount;
public int dwhitrate;
public int dwsizelow;
public int dwsizehigh;
public FILETIME lastmodifiedtime;
public FILETIME expiretime;
public FILETIME lastaccesstime;
public FILETIME lastsynctime;
public IntPtr lpheaderinfo;
public int dwheaderinfosize;
public IntPtr lpszfileextension;
public int dwexemptdelta;
}
[DllImport("wininet.dll", SetLastError = true, CharSet = CharSet.Auto)]
public static extern IntPtr FindFirstUrlCacheEntry([MarshalAs(UnmanagedType.LPTStr)]   string urlsearchpattern, IntPtr lpfirstcacheentryinfo, ref   int lpdwfirstcacheentryinfobuffersize);
[DllImport("wininet.dll", SetLastError = true, CharSet = CharSet.Auto)]
public static extern bool GetUrlCacheEntryInfo([MarshalAs(UnmanagedType.LPTStr)]   string lpszurlname, IntPtr lpcacheentryinfo, ref   int lpdwcacheentryinfobuffersize);
public static string getcatchfilename(string url)
{
int nneeded = 0, nbufsize = 0;
IntPtr buf = IntPtr.Zero;
FindFirstUrlCacheEntry(null, IntPtr.Zero, ref   nneeded);
nbufsize = nneeded; buf = Marshal.AllocHGlobal(nbufsize);
internet_cache_entry_info cacheitem;
GetUrlCacheEntryInfo(url, buf, ref   nneeded);
cacheitem = (internet_cache_entry_info)Marshal.PtrToStructure(buf, typeof(internet_cache_entry_info));
string res = Marshal.PtrToStringAuto(cacheitem.lpszlocalfilename);
return (res);
}

static void Main(string[] args)
{
string str = getcatchfilename("http://profile.csdn.net/jinjazz/picture/2.jpg");
Console.WriteLine(str);
Console.Read();
}
}
}