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Проблема кэширования управления WebBrowser

Я использую элемент управления WebBrowser внутри формы Windows для отображения PDF.

Однако, когда PDF регенерируется, элемент управления WebBrowser отображает только локальную кешированную версию, а не обновленную версию с сервера.

Я использую метод Refresh(), показанный ниже, чтобы попытаться заставить элемент управления перезагрузить PDF файл, но он не работает:

_webBrowser.Navigate(pdfUrl);

_webBrowser.Refresh(WebBrowserRefreshOption.Completely)

Нужно ли мне что-то делать, чтобы заставить обновление перезагружать PDF с сервера?

4b9b3361

ОТВЕТЫ

Ответ 1

Шэн Цзян прав - вам нужен программно чистый IE-кеш. Вот пример кода, показывающий, как это сделать в С#: http://www.gutgames.com/post/Clearing-the-Cache-of-a-WebBrowser-Control.aspx

Скопировать в случае, если страница отключена:

/**
* Modified from code originally found here: 
http://support.microsoft.com/kb/326201
**/

#region Usings
using System;
using System.Runtime.InteropServices;

#endregion

namespace Utilities.Web.WebBrowserHelper
{
    /// <summary>
    /// Class for clearing the cache
    /// </summary>
    public static class WebBrowserHelper
    {
        #region Definitions/DLL Imports
        /// <summary>
        /// For PInvoke: Contains information about an entry in the Internet cache
        /// </summary>
        [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 System.Runtime.InteropServices.ComTypes.FILETIME LastModifiedTime;
            [FieldOffset(40)]
            public System.Runtime.InteropServices.ComTypes.FILETIME ExpireTime;
            [FieldOffset(48)]
            public System.Runtime.InteropServices.ComTypes.FILETIME LastAccessTime;
            [FieldOffset(56)]
            public System.Runtime.InteropServices.ComTypes.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);
        #endregion

        #region Public Static Functions

        /// <summary>
        /// Clears the cache of the web browser
        /// </summary>
        public static void ClearCache()
        {
            // Indicates that all of the cache groups in the user 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);
        }
        #endregion
    }
}

В основе этой статьи лежит статья Microsoft KB: http://support.microsoft.com/kb/326201

И чтобы упредить вопрос - да, это огромная боль в шее, и нет, нет другого пути вокруг него. Удачи!

Ответ 2

В дополнение к Serj Sagan, здесь приведен код с упрощенной обработкой ошибок, бесконечный цикл удален и 32/64-разрядный.

/**
* Modified from code originally found here: http://support.microsoft.com/kb/326201
**/
public class WebBrowserHelper
{
    #region Definitions/DLL Imports
    /// <summary>
    /// For PInvoke: Contains information about an entry in the Internet cache
    /// </summary>
    [StructLayout(LayoutKind.Explicit)]
    public struct ExemptDeltaOrReserverd
    {
        [FieldOffset(0)]
        public UInt32 dwReserved;
        [FieldOffset(0)]
        public UInt32 dwExemptDelta;
    }

    [StructLayout(LayoutKind.Sequential)]
    public struct INTERNET_CACHE_ENTRY_INFOA
    {
        public UInt32 dwStructSize;
        public IntPtr lpszSourceUrlName;
        public IntPtr lpszLocalFileName;
        public UInt32 CacheEntryType;
        public UInt32 dwUseCount;
        public UInt32 dwHitRate;
        public UInt32 dwSizeLow;
        public UInt32 dwSizeHigh;
        public FILETIME LastModifiedTime;
        public FILETIME ExpireTime;
        public FILETIME LastAccessTime;
        public FILETIME LastSyncTime;
        public IntPtr lpHeaderInfo;
        public UInt32 dwHeaderInfoSize;
        public IntPtr lpszFileExtension;
        public ExemptDeltaOrReserverd dwExemptDeltaOrReserved;
    }

    // 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);
    #endregion

    /// <summary>
    /// Clears the cache of the web browser
    /// </summary>
    public static void ClearCache()
    {
        // Indicates that all of the cache groups in the user 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;
        const int ERROR_INSUFFICIENT_BUFFER = 0x7A;

        // 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.            
        long groupId = 0;
        IntPtr enumHandle = FindFirstUrlCacheGroup(0, CACHEGROUP_SEARCH_ALL, IntPtr.Zero, 0, ref groupId, IntPtr.Zero);
        if (enumHandle != IntPtr.Zero) {
            bool more;
            do {
                // Delete a particular Cache Group.
                DeleteUrlCacheGroup(groupId, CACHEGROUP_FLAG_FLUSHURL_ONDELETE, IntPtr.Zero);
                more = FindNextUrlCacheGroup(enumHandle, ref groupId, IntPtr.Zero);
            } while (more);
        }

        // Start to delete URLs that do not belong to any group.
        int cacheEntryInfoBufferSizeInitial = 0;
        FindFirstUrlCacheEntry(null, IntPtr.Zero, ref cacheEntryInfoBufferSizeInitial);  // should always fail because buffer is too small
        if (Marshal.GetLastWin32Error() == ERROR_INSUFFICIENT_BUFFER) {
            int cacheEntryInfoBufferSize = cacheEntryInfoBufferSizeInitial;
            IntPtr cacheEntryInfoBuffer = Marshal.AllocHGlobal(cacheEntryInfoBufferSize);
            enumHandle = FindFirstUrlCacheEntry(null, cacheEntryInfoBuffer, ref cacheEntryInfoBufferSizeInitial);
            if (enumHandle != IntPtr.Zero) {
                bool more;
                do {
                    INTERNET_CACHE_ENTRY_INFOA internetCacheEntry = (INTERNET_CACHE_ENTRY_INFOA)Marshal.PtrToStructure(cacheEntryInfoBuffer, typeof(INTERNET_CACHE_ENTRY_INFOA));
                    cacheEntryInfoBufferSizeInitial = cacheEntryInfoBufferSize;
                    DeleteUrlCacheEntry(internetCacheEntry.lpszSourceUrlName);
                    more = FindNextUrlCacheEntry(enumHandle, cacheEntryInfoBuffer, ref cacheEntryInfoBufferSizeInitial);
                    if (!more && Marshal.GetLastWin32Error() == ERROR_INSUFFICIENT_BUFFER) {
                        cacheEntryInfoBufferSize = cacheEntryInfoBufferSizeInitial;
                        cacheEntryInfoBuffer = Marshal.ReAllocHGlobal(cacheEntryInfoBuffer, (IntPtr)cacheEntryInfoBufferSize);
                        more = FindNextUrlCacheEntry(enumHandle, cacheEntryInfoBuffer, ref cacheEntryInfoBufferSizeInitial);
                    }
                } while (more);
            }
            Marshal.FreeHGlobal(cacheEntryInfoBuffer);
        }
    }
}

Ответ 3

Это расширение для ответа Криса Кларка... этот код слишком важен, я считаю, что переполнение стека является более безопасным местом для его хранения, плюс я избавился от номеров строк для вас. Здесь снова ссылка на оригинальную статью: http://www.gutgames.com/post/Clearing-the-Cache-of-a-WebBrowser-Control.aspx

И код:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Runtime.InteropServices;

namespace Utilities.Web.WebBrowserHelper
{
    /**
    * Modified from code originally found here: http://support.microsoft.com/kb/326201
    **/
    public class WebBrowserHelper
    {
        #region Definitions/DLL Imports
        /// <summary>
        /// For PInvoke: Contains information about an entry in the Internet cache
        /// </summary>
        [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 System.Runtime.InteropServices.ComTypes.FILETIME LastModifiedTime;
            [FieldOffset(40)]
            public System.Runtime.InteropServices.ComTypes.FILETIME ExpireTime;
            [FieldOffset(48)]
            public System.Runtime.InteropServices.ComTypes.FILETIME LastAccessTime;
            [FieldOffset(56)]
            public System.Runtime.InteropServices.ComTypes.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);
        #endregion

        #region Public Static Functions

        /// <summary>
        /// Clears the cache of the web browser
        /// </summary>
        public static void ClearCache()
        {
            // Indicates that all of the cache groups in the user 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);
        }
        #endregion
    }
}

Ответ 4

Так как WebBrowser (на самом деле движок IE Trident) использует WinInet для работы в сети, вы можете использовать WinInet API управления кэшем, чтобы удалить кешированные файлы перед навигацией.

Ответ 5

Добавьте к URL-адресу случайный идентификатор, поэтому URL-адрес уникален каждый раз

Ответ 6

Мы обнаружили, что полностью очистка кеша занимает слишком много времени. Альтернатива, которая, кажется, работает хорошо (и исправляет проблему в исходном вопросе Refresh not working), заключается в перемещении вызова Refresh после завершения загрузки документа.

webBrowser.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(OnWebBrowserDocumentCompleted);

// ...

private void OnWebBrowserDocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)
{
    if (cacheIsStale)
    {
        webBrowser.Refresh(WebBrowserRefreshOption.Completely);
    }
}

Как определить значение cacheIsStale будет зависеть от вашего приложения.

Ответ 7

Чтобы предотвратить кеширование CSS, вы можете использовать хитрый трюк при включении файла css:

<link type="text/css" href="css/outlook.css?<?php echo date('l jS \of F Y h:i:s A'); ?>" rel="stylesheet" />

Загружает новую копию css, потому что переменная? date_stuff изменяется каждый раз.

Ответ 8

Встраивается ли PDF с тегом объекта или что-то еще? Если это так, запрос об обновлении объекта браузера не будет иметь никакого эффекта - вам нужно script средство просмотра PDF выполнить обновление (например, получить объект просмотра PDF по идентификатору из элемента управления веб-браузером), так как это скачал его.

Ответ 9

Vescan Petru на правильном пути, я думаю. Очистка кешей браузера IE довольно тяжелая, а не удобная для пользователя. Адаптация предлагаемого кода MS, связанного с Крисом Кларком, чтобы просто очистить конкретный файл от кеша, выглядит интересным битом кода для работы, но самым простым ответом было бы захватить новое временное имя файла, а затем сделать копию целевого файла PDF с этим именем. Затем отобразите временный файл - удалив его при выходе.

Это мое рабочее решение реализовано, когда я сталкиваюсь с той же проблемой.

Ответ 10

Для тех из нас, кому еще нужно писать VB.NET, я портировал код, отправленный Сержем Саганом и Оливером Боком выше VB, и обнаружил, что он работает хорошо.

Слава Богу, эта тема существует, я действительно долго вспотел этой проблемой.

        '
    ' Modified from code originally found here: http://support.microsoft.com/kb/326201
    '
    Public Class WebBrowserHelper

Регион "Определения/Импорт DLL" 

        ''' <summary>
        ''' For PInvoke: Contains information about an entry In the Internet cache
        ''' </summary>
        <StructLayout(LayoutKind.Explicit)>
        Public Structure ExemptDeltaOrReserverd
            <FieldOffset(0)>
            Public dwReserved As UInt32
            <FieldOffset(0)>
            Public dwExemptDelta As UInt32
        End Structure

        <StructLayout(LayoutKind.Sequential)>
        Public Structure INTERNET_CACHE_ENTRY_INFOA
            Public dwStructSize As UInt32
            Public lpszSourceUrlName As IntPtr
            Public lpszLocalFileName As IntPtr
            Public CacheEntryType As UInt32
            Public dwUseCount As UInt32
            Public dwHitRate As UInt32
            Public dwSizeLow As UInt32
            Public dwSizeHigh As UInt32
            Public LastModifiedTime As FILETIME
            Public ExpireTime As FILETIME
            Public LastAccessTime As FILETIME
            Public LastSyncTime As FILETIME
            Public lpHeaderInfo As IntPtr
            Public dwHeaderInfoSize As UInt32
            Public lpszFileExtension As IntPtr
            Public dwExemptDeltaOrReserved As ExemptDeltaOrReserverd
        End Structure

        ' 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 Shared Function FindFirstUrlCacheGroup(dwFlags As Integer, dwFilter As Integer, lpSearchCondition As IntPtr, dwSearchCondition As Integer, ByRef lpGroupId As Long,
                            lpReserved As IntPtr) As IntPtr
        End Function

        ' 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 Shared Function FindNextUrlCacheGroup(hFind As IntPtr, ByRef lpGroupId As Long, lpReserved As IntPtr) As Boolean
        End Function

        ' 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 Shared Function DeleteUrlCacheGroup(GroupId As Long, dwFlags As Integer, lpReserved As IntPtr) As Boolean
        End Function

        ' For PInvoke: Begins the enumeration Of the Internet cache
        <DllImport("wininet", SetLastError:=True, CharSet:=CharSet.Auto, EntryPoint:="FindFirstUrlCacheEntryA", CallingConvention:=CallingConvention.StdCall)>
        Public Shared Function FindFirstUrlCacheEntry(<MarshalAs(UnmanagedType.LPTStr)> lpszUrlSearchPattern As String, lpFirstCacheEntryInfo As IntPtr,
                                                      ByRef lpdwFirstCacheEntryInfoBufferSize As Integer) As IntPtr
        End Function

        ' For PInvoke: Retrieves the Next entry In the Internet cache
        <DllImport("wininet", SetLastError:=True, CharSet:=CharSet.Auto, EntryPoint:="FindNextUrlCacheEntryA", CallingConvention:=CallingConvention.StdCall)>
        Public Shared Function FindNextUrlCacheEntry(hFind As IntPtr, lpNextCacheEntryInfo As IntPtr, ByRef lpdwNextCacheEntryInfoBufferSize As Integer) As Boolean
        End Function

        ' 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 Shared Function DeleteUrlCacheEntry(lpszUrlName As IntPtr) As Boolean
        End Function

Конечный регион

        ''' <summary>
        ''' Clears the cache of the web browser
        ''' </summary>
        Public Shared Sub ClearCache()
            ' Indicates that all of the cache groups in the user system should be enumerated
            Const CACHEGROUP_SEARCH_ALL As Integer = &H0
            ' 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 CACHEGROUP_FLAG_FLUSHURL_ONDELETE As Integer = &H2
            Const ERROR_INSUFFICIENT_BUFFER As Integer = &H7A

            ' 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.            
            Dim groupId As Long = 0
            Dim enumHandle As IntPtr = FindFirstUrlCacheGroup(0, CACHEGROUP_SEARCH_ALL, IntPtr.Zero, 0, groupId, IntPtr.Zero)

            If (enumHandle <> IntPtr.Zero) Then
                Dim more As Boolean

                Do
                    ' Delete a particular Cache Group.
                    DeleteUrlCacheGroup(groupId, CACHEGROUP_FLAG_FLUSHURL_ONDELETE, IntPtr.Zero)
                    more = FindNextUrlCacheGroup(enumHandle, groupId, IntPtr.Zero)
                Loop While (more)
            End If

            ' Start to delete URLs that do Not belong to any group.
            Dim cacheEntryInfoBufferSizeInitial As Integer = 0

            FindFirstUrlCacheEntry(Nothing, IntPtr.Zero, cacheEntryInfoBufferSizeInitial)  ' should always fail because buffer Is too small

            If Marshal.GetLastWin32Error() = ERROR_INSUFFICIENT_BUFFER Then
                Dim cacheEntryInfoBufferSize As Integer = cacheEntryInfoBufferSizeInitial
                Dim cacheEntryInfoBuffer As IntPtr = Marshal.AllocHGlobal(cacheEntryInfoBufferSize)

                enumHandle = FindFirstUrlCacheEntry(Nothing, cacheEntryInfoBuffer, cacheEntryInfoBufferSizeInitial)

                If (enumHandle <> IntPtr.Zero) Then
                    Dim more As Boolean
                    Do
                        Dim internetCacheEntry As INTERNET_CACHE_ENTRY_INFOA = CType(Marshal.PtrToStructure(cacheEntryInfoBuffer, GetType(INTERNET_CACHE_ENTRY_INFOA)), INTERNET_CACHE_ENTRY_INFOA)

                        cacheEntryInfoBufferSizeInitial = cacheEntryInfoBufferSize
                        DeleteUrlCacheEntry(internetCacheEntry.lpszSourceUrlName)
                        more = FindNextUrlCacheEntry(enumHandle, cacheEntryInfoBuffer, cacheEntryInfoBufferSizeInitial)

                        If Not more AndAlso Marshal.GetLastWin32Error() = ERROR_INSUFFICIENT_BUFFER Then
                            cacheEntryInfoBufferSize = cacheEntryInfoBufferSizeInitial
                            cacheEntryInfoBuffer = Marshal.ReAllocHGlobal(cacheEntryInfoBuffer, CType(cacheEntryInfoBufferSize, IntPtr))
                            more = FindNextUrlCacheEntry(enumHandle, cacheEntryInfoBuffer, cacheEntryInfoBufferSizeInitial)
                        End If
                    Loop While (more)
                End If

                Marshal.FreeHGlobal(cacheEntryInfoBuffer)
            End If
        End Sub
    End Class

Ответ 11

Для того, что стоит, более простым средством достижения вашей цели может быть просто сделать URI не кэшируемым, что-то вроде этого:

        int junkData = rnd.Next(1, 1000);
        System.Uri pugme = new System.Uri("http://pugbomb.me/?" + junkData.ToString());
        webBrowser.Navigate(pugme);