it-swarm.com.de

Problem beim Zwischenspeichern des WebBrowser-Steuerelements

Ich verwende das WebBrowser-Steuerelement in einem Windows Form, um eine PDF-Datei anzuzeigen.

Bei der Neuerstellung von PDF zeigt das WebBrowser-Steuerelement jedoch nur die lokal zwischengespeicherte Version und nicht die aktualisierte Version des Servers an.

Ich verwende die unten gezeigte Refresh () -Methode, um zu versuchen, das Steuerelement zum erneuten Laden der PDF-Datei zu zwingen, aber es funktioniert nicht:

_webBrowser.Navigate(pdfUrl);

_webBrowser.Refresh(WebBrowserRefreshOption.Completely)

Muss ich noch etwas tun, um die Aktualisierung zu erzwingen, um die PDF vom Server neu zu laden?

28
Gurpreet Singh

Sheng Jiang ist korrekt - Sie benötigen den programmgesteuert leeren IE-Cache. Beispielcode zeigt, wie dies in c #: http://www.gutgames.com/post/Clearing-the-Cache-of-a-WebBrowser-Control.aspx

Kopieren Sie für den Fall, dass die Seite offline ist:

/**
* 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'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);
        }
        #endregion
    }
}

Es basiert stark auf dem Microsoft KB-Artikel hier: http://support.Microsoft.com/kb/326201

Und um die Frage vorwegzunehmen - ja, das ist ein enormer Schmerz im Hals und nein, da gibt es keinen anderen Weg. Viel Glück!

25
Chris Clark

Neben Serj Sagan ist hier der Code mit bizarrer Fehlerbehandlung vereinfacht, die Endlosschleife entfernt und 32/64-Bit-fähig.

/**
* 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'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;
        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);
        }
    }
}
30
Oliver Bock

Dies ist eine Erweiterung der Antwort von Chris Clark. Dieser Code ist zu wichtig. Ich denke, der Stapelüberlauf ist ein sicherer Ort, um ihn zu behalten, und ich habe die Zeilennummern für Sie weggelassen. Hier nochmal ein Link zum Originalartikel: http://www.gutgames.com/post/Clearing-the-Cache-of-a-WebBrowser-Control.aspx

Und der Code:

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'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);
        }
        #endregion
    }
}
12
Serj Sagan

Da der WebBrowser (eigentlich die Trident-Engine des IE) WinInet für Netzwerke verwendet, können Sie die cache-Management-APIs von WinInet [] verwenden, um die zwischengespeicherten Dateien vor dem Navigieren zu entfernen.

4

Wir haben festgestellt, dass das vollständige Löschen des Cache zu lange dauert. Eine gut funktionierende Alternative (und behebt das Problem in der ursprünglichen Frage, dass das Aktualisieren nicht funktioniert), besteht darin, den Aufruf nach dem Laden des Dokuments auf Aktualisieren zu verschieben.

webBrowser.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(OnWebBrowserDocumentCompleted);

// ...

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

Wie Sie den Wert von cacheIsStale bestimmen, hängt von Ihrer Anwendung ab.

2
x5657

Fügen Sie der URL eine zufällige ID hinzu, damit die URL jedes Mal eindeutig ist

2
Vescan Petru

Um das CSS-Caching zu verhindern, können Sie beim Einfügen der CSS-Datei einen hinterlistigen Trick verwenden:

<link type = "text/css" href = "css/Outlook.css? <? php Echo-Datum ('l jS\von F y h: i: s A');

Es lädt eine neue Kopie der CSS herunter, da sich der? Date_stuff jedes Mal ändert.

1
Clive

Wird das PDF mit einem Objekt-Tag oder etwas eingebettet? Wenn dies der Fall ist, hat das Aktualisieren des Browserobjekts keine Auswirkung. Sie müssen den Viewer PDF für die Aktualisierung mit einem Skript versehen (z. B. das Viewer-Objekt PDF nach ID aus dem Webbrowser abrufen Kontrolle), da es das ist, was es heruntergeladen hat.

0
nitzmahone

Für diejenigen von uns, die noch VB.NET schreiben müssen, portierte ich den von Serj Sagan und Oliver Bock veröffentlichten Code auf VB und stellte fest, dass dies gut funktioniert.

Gott sei Dank, dass dieser Thread existiert, schwitzte ich dieses Thema lange Zeit.

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

Region "Definitionen/DLL-Importe"

        ''' <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

Region beenden

        ''' <summary>
        ''' Clears the cache of the web browser
        ''' </summary>
        Public Shared Sub ClearCache()
            ' Indicates that all of the cache groups in the user's 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
0
Mark K

Vescan Petru ist auf dem richtigen Weg, denke ich. Das Löschen der IE Browser-Caches ist ziemlich schwerfällig und nicht benutzerfreundlich. Die Anpassung des vorgeschlagenen MS-Codes, der von Chris Clark verknüpft wurde, um nur die bestimmte Datei aus dem Cache zu löschen, scheint ein interessantes Stück Code zu sein. Die einfachste Antwort wäre, einen neuen temporären Dateinamen zu übernehmen und dann eine Kopie des Ziels PDF mit diesem Namen. Zeigen Sie dann die temporäre Datei an - löschen Sie sie beim Beenden.

Das ist meine Arbeitslösung, wenn ich das gleiche Problem habe.

0
Mike