Caché y el control WebBrowser en .Net

Question

Estoy usando el control WebBrowser en .Net para ejecutar algunas conversiones de marketing de afiliación de terceros.

Tengo una tabla de cola en una base de datos con todos los scripts/imágenes para ejecutar. Repaso todo esto en una aplicación WinForms con el control WebBrowser. Después de ejecutar una secuencia de comandos/imagen, elimino el control WebBrowser, lo configuro como nulo y lo renuevo con una nueva instancia de control WebBrowser.

Considere este URL: http://renderserver/RenderScript.aspx?id=1

RenderScript.aspx muestra una imagen con una URL de ejemplo: http://3rdparty/img.ashx?id=9343

utilizo Fiddler para ver todas las peticiones y respuestas, y cuando la misma URL se ejecuta dos veces, usa algún tipo de caché Esa caché existe debajo del control WebBrowser.

Este caché significa que no se llama a img.ashx.

Intenté usar Internet Explorer para solicitar la URL: http://renderserver/RenderScript.aspx?id=1 y presioné F5. Entonces se solicita perfectamente.

Pero si hago clic en la barra de direcciones y presiono Enter para navegar nuevamente a la misma URL, no se solicita. Cuando uso Firefox, solicitaré la página y la imagen cada vez, sin importar si uso F5 o navego desde la barra de direcciones.

Encontré algunas llamadas a la API de Win32 (http://support.microsoft.com/kb/326201) que pudieron borrar el caché. Funcionó en mi máquina local. Luego, la aplicación se implementó en un servidor que ejecuta Windows Server 2003 Standard x64 (mi propia máquina es Vista x86).

Y ahora las llamadas a API para borrar la caché no funcionan.

¿Alguna idea sobre por qué las llamadas API no funcionan en Windows Server pero funcionan en Vista? Ambas máquinas ejecutan IE8.

Answer 1

tuve la s ame problema (bastante) hace un tiempo. Microsoft tiene una página que era muy servicial con esto:

http://support.microsoft.com/default.aspx?scid=http://support.microsoft.com:80/support/kb/articles/q326/2/01.asp&NoWebContent=1

me creado una clase fuera de la muestra de Microsoft, sin embargo, también tuve que añadir un par if para detener el proceso cuando no hay más elementos; Ha pasado un tiempo, pero estoy bastante seguro de que arrojaría un error (consulte ERROR_NO_MORE_ITEMS en el siguiente código).

¡Espero que sea útil!

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); 
     } 
    } 
} 

utilizarlo en su código, simplemente llame a:

IECache.ClearCache() 

antes de llamar a los métodos de navegar.

Answer 2

Fiddler utiliza fundamentalmente el mismo código que en el artículo de KB para borrar el caché de WinINET, y lo uso en Win2k3 todos los días.

En lugar de borrar todo el caché del usuario, la solución adecuada es establecer el encabezado de respuesta HTTP adecuado para prohibir el almacenamiento en caché. Puede obtener más información sobre el almacenamiento en caché de WinINET aquí: http://www.enhanceie.com/redir/?id=httpperf

(Alternativamente, podría simplemente agregar un parámetro de cadena de consulta aleatorizada; de esta forma, cada vez que el control encuentre una solicitud del recurso, la URL será diferente y la caché será por lo tanto derivada automáticamente)

Answer 3

esto debe hacer el truco:.

Response.Cache.SetCacheability(HttpCacheability.NoCache); 

Answer 4

probar este ...

[DllImport("wininet.dll", SetLastError = true)] 
     private static extern bool InternetSetOption(IntPtr hInternet, int dwOption, IntPtr lpBuffer, int lpdwBufferLength); 
private const int INTERNET_OPTION_END_BROWSER_SESSION = 42; 
private void clearCache() 
{ 
    try 
    { 
     Utilities.Web.WebBrowserHelper.WebBrowserHelper.ClearCache(); 
     InternetSetOption(IntPtr.Zero, INTERNET_OPTION_END_BROWSER_SESSION, IntPtr.Zero, 0); 
    } 
    catch (Exception exception) 
    { 
     //throw; 
    } 

} 

Answer 5

Ese artículo kb con el que todos los enlaces tienen numerosos errores (de donde vino el código fuente de la respuesta seleccionada), y he perdido ~ 2 días tratando de que funcione en todos los ajustes necesarios. Es una copia pegada a través de Internet, y hay numerosos errores reportados basados ​​en el sistema operativo y la versión de IE.

Fiddler fue escrito originalmente por un empleado de Microsoft y está impulsado por FiddlerCore.dll. Telerik (los actuales propietarios/mantenedores/vendedores) de Fiddler aún actualizan, mantienen y regalan FiddlerCore gratis. Si no desea agregar una referencia a FiddlerCore, puede desensamblar el dll, y muestra la forma CORRECTA de llamar a todas estas funciones WinINet horriblemente documentadas, pero creo que publicarlo aquí sería un perjuicio para Telerik/plagarismo.

Actualmente, Fiddlercore está alojado aquí: http://www.telerik.com/fiddler/fiddlercore

Answer 6

El código original de https://support.microsoft.com/en-us/kb/326201 parece cochecito

comprobación de la documentación de MSDN y también la versión VB aquí: https://support.microsoft.com/en-us/kb/262110

he modificado el código como esto y ahora porque funciona para mí (el problema estaba en la ejecución de FindNextUrlCacheGroup y FindNextUrlCacheEntry):

using System; 
using System.Runtime.InteropServices; 

namespace Q326201CS 
{ 
    // Class for deleting the cache. 
    public class DeleteIECache 
    { 
     // 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 doDelete() 
     { 
      // 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 || (!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);  
     } 
    } 
}