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How to delete my temporary internet files


Posted Date: 21 Jul 2006      Posted By:: Jebin     Member Level: Bronze    Member Rank: 0     Points: 2   Responses: 1



Can any one plz suggest me how i can delete my temporary internet files
within my Asp.net page. I am using C# as the code behind language.




Responses

#64083    Author: Abhishek Arya      Member Level: Gold      Member Rank: 23     Date: 21/Jul/2006   Rating: 2 out of 52 out of 5     Points: 2

WinInet Functions
To clear the cache directly, you can use the following WinInet functions: • Use the FindFirstURLCacheEntry function to find the first cache entry.
• Use the FindNextUrlCacheEntry function to enumerate through the cache.
• Use the DeleteUrlCacheEntry function to delete each entry.
The code sample in this article uses all of these functions.

NOTE: These functions are only available with Microsoft Internet Explorer 5. Therefore, you must include the appropriate checks (which the code sample in this article includes) to prevent errors.


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Steps to Clear the Cache in Visual Basic .NET
To use the WinInet functions in Visual Basic .NET to clear all of the files in the cache, follow these steps: 1. Start Microsoft Visual Studio .NET.
2. On the File menu, point to New, and then click Project.
3. In the New Project dialog box, click Visual Basic Projects under Project Types, and then click Console Application under Templates.
4. On the Project menu, click Add Class.
5. Add the following code to the Class1 class:Imports System.Runtime.InteropServices
'Class for deleting the cache.
Public Class Class1
'For PInvoke: Contains information about an entry in the Internet cache
<StructLayout(LayoutKind.Explicit, Size:=80)> _
Public Structure INTERNET_CACHE_ENTRY_INFOA
<FieldOffset(0)> Public dwStructSize As UInt32
<FieldOffset(4)> Public lpszSourceUrlName As IntPtr
<FieldOffset(8)> Public lpszLocalFileName As IntPtr
<FieldOffset(12)> Public CacheEntryType As UInt32
<FieldOffset(16)> Public dwUseCount As UInt32
<FieldOffset(20)> Public dwHitRate As UInt32
<FieldOffset(24)> Public dwSizeLow As UInt32
<FieldOffset(28)> Public dwSizeHigh As UInt32
<FieldOffset(32)> Public LastModifiedTime As FILETIME
<FieldOffset(40)> Public ExpireTime As FILETIME
<FieldOffset(48)> Public LastAccessTime As FILETIME
<FieldOffset(56)> Public LastSyncTime As FILETIME
<FieldOffset(64)> Public lpHeaderInfo As IntPtr
<FieldOffset(68)> Public dwHeaderInfoSize As UInt32
<FieldOffset(72)> Public lpszFileExtension As IntPtr
<FieldOffset(76)> Public dwReserved As UInt32
<FieldOffset(76)> Public dwExemptDelta As UInt32
End Structure

'For PInvoke: Initiates the enumeration of the cache groups in the Internet cache
<DllImport("wininet.dll", SetLastError:=True, _
CharSet:=CharSet.Auto, _
EntryPoint:="FindFirstUrlCacheGroup", _
CallingConvention:=CallingConvention.StdCall)> _
Shared Function FindFirstUrlCacheGroup( _
ByVal dwFlags As Int32, _
ByVal dwFilter As Integer, _
ByVal lpSearchCondition As IntPtr, _
ByVal dwSearchCondition As Int32, _
ByRef lpGroupId As Long, _
ByVal lpReserved As IntPtr) As IntPtr
End Function

'For PInvoke: Retrieves the next cache group in a cache group enumeration
<DllImport("wininet.dll", _
SetLastError:=True, _
CharSet:=CharSet.Auto, _
EntryPoint:="FindNextUrlCacheGroup", _
CallingConvention:=CallingConvention.StdCall)> _
Shared Function FindNextUrlCacheGroup( _
ByVal hFind As IntPtr, _
ByRef lpGroupId As Long, _
ByVal lpReserved As IntPtr) As Boolean
End Function

'For PInvoke: Releases the specified GROUPID and any associated state in the cache index file
<DllImport("wininet.dll", _
SetLastError:=True, _
CharSet:=CharSet.Auto, _
EntryPoint:="DeleteUrlCacheGroup", _
CallingConvention:=CallingConvention.StdCall)> _
Shared Function DeleteUrlCacheGroup( _
ByVal GroupId As Long, _
ByVal dwFlags As Int32, _
ByVal lpReserved As IntPtr) As Boolean
End Function

'For PInvoke: Begins the enumeration of the Internet cache
<DllImport("wininet.dll", _
SetLastError:=True, _
CharSet:=CharSet.Auto, _
EntryPoint:="FindFirstUrlCacheEntryA", _
CallingConvention:=CallingConvention.StdCall)> _
Shared Function FindFirstUrlCacheEntry( _
<MarshalAs(UnmanagedType.LPStr)> ByVal lpszUrlSearchPattern As String, _
ByVal lpFirstCacheEntryInfo As IntPtr, _
ByRef lpdwFirstCacheEntryInfoBufferSize As Int32) As IntPtr
End Function

'For PInvoke: Retrieves the next entry in the Internet cache
<DllImport("wininet.dll", _
SetLastError:=True, _
CharSet:=CharSet.Auto, _
EntryPoint:="FindNextUrlCacheEntryA", _
CallingConvention:=CallingConvention.StdCall)> _
Shared Function FindNextUrlCacheEntry( _
ByVal hFind As IntPtr, _
ByVal 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.dll", _
SetLastError:=True, _
CharSet:=CharSet.Auto, _
EntryPoint:="DeleteUrlCacheEntryA", _
CallingConvention:=CallingConvention.StdCall)> _
Shared Function DeleteUrlCacheEntry( _
ByVal lpszUrlName As IntPtr) As Boolean
End Function

End Class


6. Add the following code to the Module1.vb module:Imports System.Runtime.InteropServices
Module Module1

Sub Main()
'Indicates that all of the cache groups in the user's system should be enumerated
Const CACHEGROUP_SEARCH_ALL = &H0
'Indicates that all of 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 = &H2
'File not found.
Const ERROR_FILE_NOT_FOUND = &H2
'No more items have been found.
Const ERROR_NO_MORE_ITEMS = 259
'Pointer to a GROUPID variable
Dim groupId As Long = 0

'Local variables
Dim cacheEntryInfoBufferSizeInitial As Integer = 0
Dim cacheEntryInfoBufferSize As Integer = 0
Dim cacheEntryInfoBuffer As IntPtr = IntPtr.Zero
Dim internetCacheEntry As Class1.INTERNET_CACHE_ENTRY_INFOA
Dim enumHandle As IntPtr = IntPtr.Zero
Dim returnValue As Boolean = 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 CacheGroup APIs are not used because the existing URL does not belong to any group.

enumHandle = Class1.FindFirstUrlCacheGroup(0, CACHEGROUP_SEARCH_ALL, IntPtr.Zero, 0, groupId, IntPtr.Zero)
'If there are no items in the Cache, you are finished.
If (Not enumHandle.Equals(IntPtr.Zero) And ERROR_NO_MORE_ITEMS.Equals(Marshal.GetLastWin32Error)) Then
Exit Sub
End If

'Loop through Cache Group, and then delete entries.
While (True)
'Delete a particular Cache Group.
returnValue = Class1.DeleteUrlCacheGroup(groupId, CACHEGROUP_FLAG_FLUSHURL_ONDELETE, IntPtr.Zero)

If (Not returnValue And ERROR_FILE_NOT_FOUND.Equals(Marshal.GetLastWin32Error())) Then
returnValue = Class1.FindNextUrlCacheGroup(enumHandle, groupId, IntPtr.Zero)
End If

If (Not returnValue And (ERROR_NO_MORE_ITEMS.Equals(Marshal.GetLastWin32Error()) Or ERROR_FILE_NOT_FOUND.Equals(Marshal.GetLastWin32Error()))) Then
Exit While
End If
End While
'Start to delete URLs that do not belong to any group.
enumHandle = Class1.FindFirstUrlCacheEntry(vbNull, IntPtr.Zero, cacheEntryInfoBufferSizeInitial)

If (Not enumHandle.Equals(IntPtr.Zero) And ERROR_NO_MORE_ITEMS.Equals(Marshal.GetLastWin32Error())) Then
Exit Sub
End If

cacheEntryInfoBufferSize = cacheEntryInfoBufferSizeInitial
cacheEntryInfoBuffer = Marshal.AllocHGlobal(cacheEntryInfoBufferSize)
enumHandle = Class1.FindFirstUrlCacheEntry(vbNull, cacheEntryInfoBuffer, cacheEntryInfoBufferSizeInitial)

While (True)
internetCacheEntry = CType(Marshal.PtrToStructure(cacheEntryInfoBuffer, GetType(Class1.INTERNET_CACHE_ENTRY_INFOA)), Class1.INTERNET_CACHE_ENTRY_INFOA)
cacheEntryInfoBufferSizeInitial = cacheEntryInfoBufferSize
returnValue = Class1.DeleteUrlCacheEntry(internetCacheEntry.lpszSourceUrlName)

If (Not returnValue) Then
'Console.WriteLine("Error Deleting: {0}", Marshal.GetLastWin32Error())
End If

returnValue = Class1.FindNextUrlCacheEntry(enumHandle, cacheEntryInfoBuffer, cacheEntryInfoBufferSizeInitial)
If (Not returnValue And ERROR_NO_MORE_ITEMS.Equals(Marshal.GetLastWin32Error())) Then
Exit While
End If

If (Not returnValue And cacheEntryInfoBufferSizeInitial > cacheEntryInfoBufferSize) Then

cacheEntryInfoBufferSize = cacheEntryInfoBufferSizeInitial
Dim tempIntPtr As New IntPtr(cacheEntryInfoBufferSize)
cacheEntryInfoBuffer = Marshal.ReAllocHGlobal(cacheEntryInfoBuffer, tempIntPtr)
returnValue = Class1.FindNextUrlCacheEntry(enumHandle, cacheEntryInfoBuffer, cacheEntryInfoBufferSizeInitial)
End If
End While
Marshal.FreeHGlobal(cacheEntryInfoBuffer)

End Sub

End Module


7. Compile and then run the project.
8. To confirm that the temporary Internet files in your cache have been deleted, follow these steps in Microsoft Internet Explorer:a. On the Tools menu, click Internet Options.
b. In the Temporary Internet files area on the General tab, click Settings.
c. Click View Files. Notice that all of the files in the Internet Explorer cache have been deleted.


 
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