我正在使用Windows Form中的WebBrowser控件来显示PDF文档。
然而，每当PDF文档被重新生成时，WebBrowser控件仅显示其本地缓存版本，而不是来自服务器的更新版本。
我正在尝试使用下面展示的Refresh()方法来强制控件重新加载PDF文档，但它没有起作用：
_webBrowser.Navigate(pdfUrl);
_webBrowser.Refresh(WebBrowserRefreshOption.Completely)
我是否需要做其他任何事情来强制刷新从服务器重新加载PDF?
关于Serj Sagan所提到的问题，以下是简化后的代码，将奇怪的错误处理方式删除，移除了无限循环，并且支持32/64位系统。
/**
* 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);
}
}
}
Office365 登录。我需要做的是停止在我的应用程序中缓存 office365。你有什么想法或建议来解决这个问题吗？ - user2749605Sheng Jiang是正确的 - 你需要以编程方式清除IE的缓存。下面是一个示例代码，展示如何在C#中实现这个功能:
http://www.gutgames.com/post/Clearing-the-Cache-of-a-WebBrowser-Control.aspx如果该页面无法访问，可以参考以下内容:
/**
* 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
}
}
这是基于微软KB文章的大量工作： http://support.microsoft.com/kb/326201
提前回答问题 - 是的，这很麻烦，没有其他解决方法。祝好运！
代码如下：
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
}
}
Marshal.GetLastWin32Error()并不总是返回0。现在，我不会争论是否存在这种情况，即Marshal.GetLastWin32Error()永远不等于ERROR_NO_MORE_ITEMS，但这是一个与你所断言的不同的错误。 - Serj SaganwebBrowser.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(OnWebBrowserDocumentCompleted);
// ...
private void OnWebBrowserDocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)
{
if (cacheIsStale)
{
webBrowser.Refresh(WebBrowserRefreshOption.Completely);
}
}
cacheIsStale的值将取决于您的应用程序。为URL添加一个随机ID，以使每次URL都是唯一的
<link type="text/css" href="css/outlook.css?<?php echo date('l jS \of F Y h:i:s A'); ?>" rel="stylesheet" />
这会下载CSS的新副本，因为?date_stuff每次都会改变。对于那些仍需要编写VB.NET的人，我将Serj Sagan和Oliver Bock上面发布的代码移植到了VB中，并发现它可以很好地工作。
谢天谢地有这个帖子存在，我为这个问题担心了很长时间。
'
' Modified from code originally found here: http://support.microsoft.com/kb/326201
'
Public Class WebBrowserHelper
''' <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
''' <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
PDF是否被嵌入了对象标签或其他内容？如果是这样的话，要求浏览器对象刷新将没有任何效果-您必须编写脚本来刷新PDF查看器（例如，通过从WebBrowser控件获取PDF查看器对象ID），因为它是下载的。
Vescan Petru 正在正确的方向上。清除IE浏览器缓存是相当粗暴且不友好的做法。将Chris Clark提供的建议的微软代码适应到只清除特定文件的缓存看起来是一个有趣的代码片段，但最简单的解决方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 - 在退出时删除它。
这是我遇到同样问题时实施的工作解决方案。