我正在使用.Net中的WebBrowser控件来执行一些第三方成员(member)营销转换。
我在数据库中有一个队列表，其中包含要执行的所有脚本/图像。我使用WebBrowser控件在WinForms应用程序中浏览所有这些内容。执行完脚本/图像后，我将WebBrowser控件放下，将其设置为null，然后使用新的WebBrowser控件实例对其进行更新。
考虑以下URL:http://renderserver/RenderScript.aspx?id=1
RenderScript.aspx显示的图像的URL例如:http://3rdparty/img.ashx?id=9343
我使用Fiddler查看所有请求和响应，并且当两次执行相同的URL时，它使用某种缓存。该缓存存在于WebBrowser控件本身的下面。
此缓存意味着不调用img.ashx。
我尝试使用Internet Explorer请求URL:http://renderserver/RenderScript.aspx?id=1，然后按F5键。然后，它是完美的要求。
但是，如果我单击地址栏，然后按Enter键，再次导航到相同的URL，则不需要输入该URL。当我使用Firefox时，无论我使用F5还是从地址栏导航，都将每次都请求页面和图像。
我发现一些Win32 API调用(http://support.microsoft.com/kb/326201)能够清除缓存。它在我的本地机器上工作。然后将该应用程序部署到运行Windows Server 2003 Standard x64(我自己的计算机是Vista x86)的服务器上。
现在，用于清除缓存的API调用不起作用。
关于为什么API调用在Windows Server上不起作用，但在Vista上起作用的任何想法？两台机器都运行IE8。
最佳答案
前一段时间我有同样的问题。 Microsoft的页面对此非常有帮助:
http://support.microsoft.com/default.aspx?scid=http://support.microsoft.com:80/support/kb/articles/q326/2/01.asp&NoWebContent=1
我从Microsoft的示例中创建了一个类，但是当没有更多项时，我还必须添加一对if语句来停止处理。已经有一段时间了，但是我很确定它会抛出错误(请参见下面的代码中的ERROR_NO_MORE_ITEMS)。
希望对您有所帮助!
using System;
using System.Runtime.InteropServices;
// copied from: http://support.microsoft.com/default.aspx?scid=http://support.microsoft.com:80/support/kb/articles/q326/2/01.asp&NoWebContent=1
namespace PowerCode
{
public class IECache
{
// For PInvoke: Contains information about an entry in the Internet cache
[StructLayout(LayoutKind.Explicit, Size = 80)]
public struct INTERNET_CACHE_ENTRY_INFOA
{
[FieldOffset(0)]
public uint dwStructSize;
[FieldOffset(4)]
public IntPtr lpszSourceUrlName;
[FieldOffset(8)]
public IntPtr lpszLocalFileName;
[FieldOffset(12)]
public uint CacheEntryType;
[FieldOffset(16)]
public uint dwUseCount;
[FieldOffset(20)]
public uint dwHitRate;
[FieldOffset(24)]
public uint dwSizeLow;
[FieldOffset(28)]
public uint dwSizeHigh;
[FieldOffset(32)]
public FILETIME LastModifiedTime;
[FieldOffset(40)]
public FILETIME ExpireTime;
[FieldOffset(48)]
public FILETIME LastAccessTime;
[FieldOffset(56)]
public FILETIME LastSyncTime;
[FieldOffset(64)]
public IntPtr lpHeaderInfo;
[FieldOffset(68)]
public uint dwHeaderInfoSize;
[FieldOffset(72)]
public IntPtr lpszFileExtension;
[FieldOffset(76)]
public uint dwReserved;
[FieldOffset(76)]
public uint dwExemptDelta;
}
// For PInvoke: Initiates the enumeration of the cache groups in the Internet cache
[DllImport(@"wininet", SetLastError = true, CharSet = CharSet.Auto, EntryPoint = "FindFirstUrlCacheGroup", CallingConvention = CallingConvention.StdCall)]
public static extern IntPtr FindFirstUrlCacheGroup( int dwFlags, int dwFilter, IntPtr lpSearchCondition, int dwSearchCondition, ref long lpGroupId, IntPtr lpReserved );
// For PInvoke: Retrieves the next cache group in a cache group enumeration
[DllImport(@"wininet", SetLastError = true, CharSet = CharSet.Auto, EntryPoint = "FindNextUrlCacheGroup", CallingConvention = CallingConvention.StdCall)]
public static extern bool FindNextUrlCacheGroup( IntPtr hFind, ref long lpGroupId, IntPtr lpReserved );
// For PInvoke: Releases the specified GROUPID and any associated state in the cache index file
[DllImport(@"wininet", SetLastError = true, CharSet = CharSet.Auto, EntryPoint = "DeleteUrlCacheGroup", CallingConvention = CallingConvention.StdCall)]
public static extern bool DeleteUrlCacheGroup( long GroupId, int dwFlags, IntPtr lpReserved );
// For PInvoke: Begins the enumeration of the Internet cache
[DllImport(@"wininet", SetLastError = true, CharSet = CharSet.Auto, EntryPoint = "FindFirstUrlCacheEntryA", CallingConvention = CallingConvention.StdCall)]
public static extern IntPtr FindFirstUrlCacheEntry( [MarshalAs(UnmanagedType.LPTStr)] string lpszUrlSearchPattern, IntPtr lpFirstCacheEntryInfo, ref int lpdwFirstCacheEntryInfoBufferSize );
// For PInvoke: Retrieves the next entry in the Internet cache
[DllImport(@"wininet", SetLastError = true, CharSet = CharSet.Auto, EntryPoint = "FindNextUrlCacheEntryA", CallingConvention = CallingConvention.StdCall)]
public static extern bool FindNextUrlCacheEntry( IntPtr hFind, IntPtr lpNextCacheEntryInfo, ref int lpdwNextCacheEntryInfoBufferSize );
// For PInvoke: Removes the file that is associated with the source name from the cache, if the file exists
[DllImport(@"wininet", SetLastError = true, CharSet = CharSet.Auto, EntryPoint = "DeleteUrlCacheEntryA", CallingConvention = CallingConvention.StdCall)]
public static extern bool DeleteUrlCacheEntry( IntPtr lpszUrlName );
public static void ClearCache()
{
// Indicates that all of the cache groups in the user's system should be enumerated
const int CACHEGROUP_SEARCH_ALL = 0x0;
// Indicates that all the cache entries that are associated with the cache group
// should be deleted, unless the entry belongs to another cache group.
const int CACHEGROUP_FLAG_FLUSHURL_ONDELETE = 0x2;
// File not found.
const int ERROR_FILE_NOT_FOUND = 0x2;
// No more items have been found.
const int ERROR_NO_MORE_ITEMS = 259;
// Pointer to a GROUPID variable
long groupId = 0;
// Local variables
int cacheEntryInfoBufferSizeInitial = 0;
int cacheEntryInfoBufferSize = 0;
IntPtr cacheEntryInfoBuffer = IntPtr.Zero;
INTERNET_CACHE_ENTRY_INFOA internetCacheEntry;
IntPtr enumHandle = IntPtr.Zero;
bool returnValue = false;
// Delete the groups first.
// Groups may not always exist on the system.
// For more information, visit the following Microsoft Web site:
// http://msdn.microsoft.com/library/?url=/workshop/networking/wininet/overview/cache.asp
// By default, a URL does not belong to any group. Therefore, that cache may become
// empty even when the CacheGroup APIs are not used because the existing URL does not belong to any group.
enumHandle = FindFirstUrlCacheGroup(0, CACHEGROUP_SEARCH_ALL, IntPtr.Zero, 0, ref groupId, IntPtr.Zero);
// If there are no items in the Cache, you are finished.
if (enumHandle != IntPtr.Zero && ERROR_NO_MORE_ITEMS == Marshal.GetLastWin32Error()) {
return;
}
// Loop through Cache Group, and then delete entries.
while (true) {
if (ERROR_NO_MORE_ITEMS == Marshal.GetLastWin32Error() || ERROR_FILE_NOT_FOUND == Marshal.GetLastWin32Error()) {
break;
}
// Delete a particular Cache Group.
returnValue = DeleteUrlCacheGroup(groupId, CACHEGROUP_FLAG_FLUSHURL_ONDELETE, IntPtr.Zero);
if (!returnValue && ERROR_FILE_NOT_FOUND == Marshal.GetLastWin32Error()) {
returnValue = FindNextUrlCacheGroup(enumHandle, ref groupId, IntPtr.Zero);
}
if (!returnValue && (ERROR_NO_MORE_ITEMS == Marshal.GetLastWin32Error() || ERROR_FILE_NOT_FOUND == Marshal.GetLastWin32Error())) {
break;
}
}
// Start to delete URLs that do not belong to any group.
enumHandle = FindFirstUrlCacheEntry(null, IntPtr.Zero, ref cacheEntryInfoBufferSizeInitial);
if (enumHandle != IntPtr.Zero && ERROR_NO_MORE_ITEMS == Marshal.GetLastWin32Error()) {
return;
}
cacheEntryInfoBufferSize = cacheEntryInfoBufferSizeInitial;
cacheEntryInfoBuffer = Marshal.AllocHGlobal(cacheEntryInfoBufferSize);
enumHandle = FindFirstUrlCacheEntry(null, cacheEntryInfoBuffer, ref cacheEntryInfoBufferSizeInitial);
while (true) {
internetCacheEntry = (INTERNET_CACHE_ENTRY_INFOA)Marshal.PtrToStructure(cacheEntryInfoBuffer, typeof(INTERNET_CACHE_ENTRY_INFOA));
if (ERROR_NO_MORE_ITEMS == Marshal.GetLastWin32Error()) {
break;
}
cacheEntryInfoBufferSizeInitial = cacheEntryInfoBufferSize;
returnValue = DeleteUrlCacheEntry(internetCacheEntry.lpszSourceUrlName);
if (!returnValue) {
returnValue = FindNextUrlCacheEntry(enumHandle, cacheEntryInfoBuffer, ref cacheEntryInfoBufferSizeInitial);
}
if (!returnValue && ERROR_NO_MORE_ITEMS == Marshal.GetLastWin32Error()) {
break;
}
if (!returnValue && cacheEntryInfoBufferSizeInitial > cacheEntryInfoBufferSize) {
cacheEntryInfoBufferSize = cacheEntryInfoBufferSizeInitial;
cacheEntryInfoBuffer = Marshal.ReAllocHGlobal(cacheEntryInfoBuffer, (IntPtr)cacheEntryInfoBufferSize);
returnValue = FindNextUrlCacheEntry(enumHandle, cacheEntryInfoBuffer, ref cacheEntryInfoBufferSizeInitial);
}
}
Marshal.FreeHGlobal(cacheEntryInfoBuffer);
}
}
}
要在您的代码中使用它，只需调用:
IECache.ClearCache()
在调用导航方法之前。