我在Windows窗体中使用WebBrowser控件来显示PDF。
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)
我是否必须执行其他操作才能强制刷新从服务器重新加载PDF？
答案 0 :(得分：30)
继Serj Sagan之后，这里的代码简化了奇怪的错误处理，删除了无限循环，并且支持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);
}
}
}
答案 1 :(得分：26)
盛江是正确的 - 您需要以编程方式清除IE的缓存。以下示例代码显示了如何在c＃中执行此操作： http://www.gutgames.com/post/Clearing-the-Cache-of-a-WebBrowser-Control.aspx
如果页面脱机，请复制：
/**
* 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Microsoft知识库文章： http://support.microsoft.com/kb/326201
并预先解决这个问题 - 是的，这是一个巨大的痛苦，不，没有别的办法。祝你好运！
答案 2 :(得分：12)
这是克里斯·克拉克答案的延伸......这段代码太重要了，我认为堆栈溢出是一个更安全的地方来保存它，而且我为你排除了行号。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
}
}
答案 3 :(得分：4)
由于WebBrowser（实际上是IE的Trident引擎）使用WinInet进行网络连接，因此您可以在导航之前使用WinInet的cache management APIs删除缓存的文件。
答案 4 :(得分：2)
在网址中添加一个随机ID，以便每次都是唯一的网址
答案 5 :(得分：2)
我们发现完全清除缓存需要的时间太长。一个似乎运行良好的替代方案（并修复了原始问题“刷新不起作用”中的问题）是在文档加载完成后将调用移动到“刷新”。
webBrowser.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(OnWebBrowserDocumentCompleted);
// ...
private void OnWebBrowserDocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)
{
if (cacheIsStale)
{
webBrowser.Refresh(WebBrowserRefreshOption.Completely);
}
}
如何确定cacheIsStale的值取决于您的应用程序。
答案 6 :(得分：1)
要防止CSS缓存，您可以在包含css文件时使用偷偷摸摸的技巧：
<link type="text/css" href="css/outlook.css?<?php echo date('l jS \of F Y h:i:s A'); ?>" rel="stylesheet" />
它会下载css的新副本，因为？date_stuff每次都会更改。
答案 7 :(得分：0)
PDF是否嵌入了对象标签或其他内容？如果是这样，请求浏览器对象刷新将不会产生任何影响 - 您必须编写PDF查看器脚本以进行刷新（例如，通过Web浏览器控件中的ID获取PDF查看器对象），因为这是下载它的内容
答案 8 :(得分：0)
我认为Vescan Petru走在正确的轨道上。清除IE浏览器缓存非常繁重，而且不是用户友好的。修改由Chris Clark链接的建议MS代码以清除缓存中的特定文件，看起来有一些有用的代码，但最简单的答案是获取新的临时文件名，然后复制目标PDF文件用这个名字。然后显示临时文件 - 退出时将其删除。
这是我遇到同样问题时实施的工作解决方案。
答案 9 :(得分：0)
对于我们这些仍然需要编写VB.NET的人，我将Serj Sagan和Oliver Bock发布的代码移植到VB上，发现它运行良好。
谢天谢地，这个帖子存在，我真的在这个问题上冒了很长时间。
'
' 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
答案 10 :(得分：0)
TimeSpan serialNoCache = DateTime.Now.TimeOfDay;
string urlNocache = string.Format("{0}?v={1}", "https://www.google.com/", serialNoCache.ToString());
this.webBrowser.Navigate(urlNocache);