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WebBrowser控件缓存问题

  •  28
  • Gurpreet Singh  · 技术社区  · 15 年前

    我正在使用Windows窗体中的WebBrowser控件来显示PDF。

    但是,每当重新生成PDF时,WebBrowser控件仅显示其本地缓存版本,而不显示服务器的更新版本。

    我正在使用下面显示的refresh()方法尝试强制控件重新加载PDF,但它不起作用:

    _webBrowser.Navigate(pdfUrl);
    
    _webBrowser.Refresh(WebBrowserRefreshOption.Completely)
    

    是否必须执行其他操作才能强制刷新以从服务器重新加载PDF?

    10 回复  |  直到 7 年前
        1
  •  25
  •   user8607806 Ralph King    7 年前

    盛江是对的-你需要程序性地清除IE的缓存。下面是演示如何在C中执行此操作的示例代码: http://www.gutgames.com/post/Clearing-the-Cache-of-a-WebBrowser-Control.aspx

    复制以防页面脱机:

    /**
    * 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
        }
    }
    

    它主要基于微软知识库的文章: http://support.microsoft.com/kb/326201

    为了先发制人这个问题——是的,这是一个巨大的颈部疼痛,而不是,没有其他的方法可以解决这个问题。祝你好运!

        2
  •  30
  •   Oliver Bock    11 年前

    对于serj-sagan来说,这里的代码简化了奇怪的错误处理,删除了无限循环,支持32/64位。

    /**
    * 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);
            }
        }
    }
    
        3
  •  12
  •   Serj Sagan    12 年前

    这是克里斯克拉克回答的延伸…这段代码太重要了,我认为栈溢出是一个更安全的地方来保存它,另外我为您去掉了行号。以下是原始文章的链接: http://www.gutgames.com/post/Clearing-the-Cache-of-a-WebBrowser-Control.aspx

    代码:

    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
        }
    }
    
        4
  •  4
  •   Sheng Jiang 蒋晟    15 年前

    因为Webbrowser(实际上是IE的Trident引擎)使用wininet进行网络连接,所以可以使用wininet的 cache management APIs 在导航之前删除缓存文件。

        5
  •  2
  •   Vescan Petru    13 年前

    向URL中添加随机ID,以便每次URL都是唯一的

        6
  •  2
  •   x5657    10 年前

    我们发现完全清除缓存需要很长时间。另一个看起来工作良好的方法(并解决了原始刷新不工作问题中的问题)是在文档加载完成后移动对刷新的调用。

    webBrowser.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(OnWebBrowserDocumentCompleted);
    
    // ...
    
    private void OnWebBrowserDocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)
    {
        if (cacheIsStale)
        {
            webBrowser.Refresh(WebBrowserRefreshOption.Completely);
        }
    }
    

    如何确定 cacheIsStale 将取决于您的申请。

        7
  •  1
  •   Clive    13 年前

    为了防止CSS缓存,您可以在包含CSS文件时使用一个秘密的技巧:

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

    它下载了一个新的CSS副本,因为?每次都会改变日期。

        8
  •  0
  •   nitzmahone    15 年前

    PDF是否嵌入了对象标记或其他内容?如果是这样,请求浏览器对象刷新将不会有任何效果-您必须编写PDF查看器脚本来进行刷新(例如,从WebBrowser控件中按ID获取PDF查看器对象的旧版本),因为这就是下载它的原因。

        9
  •  0
  •   Mike    13 年前

    我想维斯卡·佩特鲁走对了。清除IE浏览器缓存的操作非常繁琐,用户不友好。调整由Chris Clark链接的建议MS代码以从缓存中清除特定文件看起来是一个有趣的代码,但最简单的答案是获取一个新的临时文件名,然后用该名称复制目标PDF文件。然后显示临时文件-退出时将其删除。

    当我遇到同样的问题时,这就是我的工作解决方案。

        10
  •  0
  •   Mark K    8 年前

    对于那些仍然需要编写vb.net的人来说,我把上面SerjSagan和OliverBock发布的代码移植到vb中,发现它工作得很好。

    谢天谢地,这条线已经存在了,我真的很长一段时间都在为这个问题苦恼。

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

    区域“定义/dll导入”

            ''' <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
    

    端部区域

            ''' <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