I'm just picking up VB, so this is probably a noob question. Apologies in advance.
I'm trying to wrap an XmlWriter with a class to manage memory, flushing, closing etc... so that clients don't need to worry about it.
My code is:
Option Explicit On
Option Strict Off
Imports System.Xml
Imports System.IO
Module MainModule
Sub Main()
Dim xmltest As XmlOutput = New XmlOutput("output.xml", "test")
xmltest.writeData("hello", "19.95")
End Sub
End Module
Public Class XmlOutput
Private xmlWriter As XmlWriter
Public Sub New(ByVal filename As String, ByVal calculator As String)
xmlWriter = XmlWriter.Create(filename)
xmlWriter.WriteStartDocument(True)
xmlWriter.WriteStartElement(calculator)
End Sub
Protected Overrides Sub Finalize()
xmlWriter.WriteEndElement()
xmlWriter.WriteEndDocument()
xmlWriter.Dispose()
End Sub
Public Sub writeData(ByVal head As String, ByVal value As String)
xmlWriter.WriteElementString(head, value)
End Sub
End Class
When I run this I get the following error:
System.ObjectDisposedException was unhandled
HResult=-2146232798
Message=Cannot access a closed file.
ObjectName=""
Source=mscorlib
StackTrace:
at System.IO.__Error.FileNotOpen()
at System.IO.FileStream.Flush(Boolean flushToDisk)
at System.IO.FileStream.Flush()
at System.Xml.XmlUtf8RawTextWriter.Close()
at System.Xml.XmlRawWriter.Close(WriteState currentState)
at System.Xml.XmlWellFormedWriter.Close()
at System.Xml.XmlWriter.Dispose(Boolean disposing)
at System.Xml.XmlWriter.Dispose()
at XmlOutputTest.XmlOutput.Finalize()
InnerException:
This looks like the XmlWriter has closed the FileStream before the XmlWriter is closed. Since the XmlWriter has responsibility for the FileStream I expected it to know when the FileStream had been closed.
Questions:
Why is the XmlWriter trying to close something it's already closed (or maybe I'm interpreting the stack trace incorrectly)?
What do I need to do to fix this?
Related
Getting the error "Event 'Load' cannot be found" referring to "Handles MyBase.Load" Please see attached code. Any help much appreciated!
I have many other applications set up the same way and they all work. However, these were in an older version of Visual Studio.
Option Explicit On
Option Strict On
Imports System, System.IO
Imports System.Text
Public Class Form1
Private Sub cleanXMLDialog_Load(ByVal eventSender As System.Object, ByVal
eventArgs As System.EventArgs) Handles MyBase.Load
Main()
End
End Sub
Public Sub Main()
Dim directories() As String = Directory.GetDirectories("C:\")
Dim files() As String = Directory.GetFiles("C:\", "*.dll")
DirSearch("c:\")
End Sub
Sub DirSearch(ByVal sDir As String)
Dim d As String
Dim f As String
Try
For Each d In Directory.GetDirectories(sDir)
For Each f In Directory.GetFiles(d, "*.xml")
'Dim Response As String = MsgBox(f)
Debug.Write(f)
Next
DirSearch(d)
Next
Catch excpt As System.Exception
Debug.WriteLine(excpt.Message)
End Try
End Sub
End Class
Load should happen without this error.
This is the class declaration:
Public Class Form1
It looks like you intend this to inherit from a windows Form type, but there's nothing here to make that happen.
You may want this:
Public Class Form1 Inherits System.Windows.Forms.Form
but even this is unlikely to really accomplish anything. It's not enough just to inherit from the Form type if you don't have any controls are properties set and don't ever show the form.
Did you accidentally create a Console or Class Library project when you mean to create a WinForms project?
I am instantiating a deserializing class to fetch data from a binary-formatted data file. This appraoch seems to work fine most of the time, except when some of the data files get larger than 2-4 MB, and the following exception is thrown (at the code line with comments, below):
"The runtime has encountered a fatal error. The address of the error was at 0x722de24f, on thread 0x30e0. The error code is 0xc0000005. This error may be a bug in the CLR or in the unsafe or non-verifiable portions of user code. Common sources of this bug include user marshaling errors for COM-interop or PInvoke, which may corrupt the stack."
Here is the code:
<Serializable()>
Public Class deserializedata
Public Property sernumrows As Integer
Public Property sernumcols As Integer
Public Property serx As Object(,)
Public snumrows, snumcols As Integer
Public sx As Object(,)
Sub New(ByRef snumrows As Integer, ByRef snumcols As Integer, ByRef sx(,) As Object, ByVal sfilename as String)
Dim param_obj(0) As Object
param_obj(0) = sfilename
Call deser(param_obj)
End Sub
Sub deser(ByVal param_obj)
sfilename = param_obj(0)
Using stream As FileStream = File.Open(sfilename, FileMode.Open, FileAccess.Read, FileShare.Read)
Dim formatter As New BinaryFormatter()
Dim myser As Object = formatter.Deserialize(stream) 'this is where exception is being thrown
snumrows = myser.sernumrows
snumcols = myser.sernumcols
sx = myser.serx
stream.Close()
End Using
End Sub
End Class
I was wondering, how can I get the percentage of this being done, so I can display it on a progress bar?
ZipFile.CreateFromDirectory("C:\temp\folder", "C:\temp\folder.zip")
and also
ZipFile.ExtractToDirectory("C:\temp\folder.zip", "C:\temp\folder")
This doesnt have any events or callbacks that you can use to report progress. Simply means you cant with the .Net version. If you used the 7-Zip library you can do this easily.
I came across this question while checking for related questions for the identical question, asked for C# code. It is true that the .NET static ZipFile class does not offer progress reporting. However, it is not hard to do using the ZipArchive implementation, available since earlier versions of .NET.
The key is to use a Stream wrapper that will report bytes read and written, and insert that in the data pipeline while creating or extracting the archive.
I wrote a version in C# for an answer to the other question, and since I didn't find any VB.NET examples, figured it would be helpful to include a VB.NET version on this question.
(Arguably, I could include both examples in a single answer and propose closing one of the questions as a duplicate of the other. But since it's doubtful the close vote would result in an actual closure, the connection between the two questions would not be as obvious as it should be. I think for best visibility to future users trying to find the solution appropriate for their needs, leaving this as two different questions is better.)
The foundation of the solution is the Stream wrapper class:
StreamWithProgress.vb
Imports System.IO
Public Class StreamWithProgress
Inherits Stream
' NOTE For illustration purposes. For production code, one would want To
' override *all* of the virtual methods, delegating to the base _stream object,
' to ensure performance optimizations in the base _stream object aren't
' bypassed.
Private ReadOnly _stream As Stream
Private ReadOnly _readProgress As IProgress(Of Integer)
Private ReadOnly _writeProgress As IProgress(Of Integer)
Public Sub New(Stream As Stream, readProgress As IProgress(Of Integer), writeProgress As IProgress(Of Integer))
_stream = Stream
_readProgress = readProgress
_writeProgress = writeProgress
End Sub
Public Overrides ReadOnly Property CanRead As Boolean
Get
Return _stream.CanRead
End Get
End Property
Public Overrides ReadOnly Property CanSeek As Boolean
Get
Return _stream.CanSeek
End Get
End Property
Public Overrides ReadOnly Property CanWrite As Boolean
Get
Return _stream.CanWrite
End Get
End Property
Public Overrides ReadOnly Property Length As Long
Get
Return _stream.Length
End Get
End Property
Public Overrides Property Position As Long
Get
Return _stream.Position
End Get
Set(value As Long)
_stream.Position = value
End Set
End Property
Public Overrides Sub Flush()
_stream.Flush()
End Sub
Public Overrides Sub SetLength(value As Long)
_stream.SetLength(value)
End Sub
Public Overrides Function Seek(offset As Long, origin As SeekOrigin) As Long
Return _stream.Seek(offset, origin)
End Function
Public Overrides Sub Write(buffer() As Byte, offset As Integer, count As Integer)
_stream.Write(buffer, offset, count)
_writeProgress?.Report(count)
End Sub
Public Overrides Function Read(buffer() As Byte, offset As Integer, count As Integer) As Integer
Dim bytesRead As Integer = _stream.Read(buffer, offset, count)
_readProgress?.Report(bytesRead)
Return bytesRead
End Function
End Class
The wrapper class can be used to implement progress-aware versions of the ZipFile static methods:
ZipFileWithProgress.vb
Imports System.IO
Imports System.IO.Compression
NotInheritable Class ZipFileWithProgress
Private Sub New()
End Sub
Public Shared Sub CreateFromDirectory(
sourceDirectoryName As String,
destinationArchiveFileName As String,
progress As IProgress(Of Double))
sourceDirectoryName = Path.GetFullPath(sourceDirectoryName)
Dim sourceFiles As FileInfo() = New DirectoryInfo(sourceDirectoryName).GetFiles("*", SearchOption.AllDirectories)
Dim totalBytes As Double = sourceFiles.Sum(Function(f) f.Length)
Dim currentBytes As Long = 0
Using archive As ZipArchive = ZipFile.Open(destinationArchiveFileName, ZipArchiveMode.Create)
For Each fileInfo As FileInfo In sourceFiles
' NOTE: naive method To Get Sub-path from file name, relative to
' input directory. Production code should be more robust than this.
' Either use Path class Or similar to parse directory separators And
' reconstruct output file name, Or change this entire method to be
' recursive so that it can follow the sub-directories And include them
' in the entry name as they are processed.
Dim entryName As String = fileInfo.FullName.Substring(sourceDirectoryName.Length + 1)
Dim entry As ZipArchiveEntry = archive.CreateEntry(entryName)
entry.LastWriteTime = fileInfo.LastWriteTime
Using inputStream As Stream = File.OpenRead(fileInfo.FullName)
Using outputStream As Stream = entry.Open()
Dim progressStream As Stream = New StreamWithProgress(inputStream,
New BasicProgress(Of Integer)(
Sub(i)
currentBytes += i
progress.Report(currentBytes / totalBytes)
End Sub), Nothing)
progressStream.CopyTo(outputStream)
End Using
End Using
Next
End Using
End Sub
Public Shared Sub ExtractToDirectory(
sourceArchiveFileName As String,
destinationDirectoryName As String,
progress As IProgress(Of Double))
Using archive As ZipArchive = ZipFile.OpenRead(sourceArchiveFileName)
Dim totalBytes As Double = archive.Entries.Sum(Function(e) e.Length)
Dim currentBytes As Long = 0
For Each entry As ZipArchiveEntry In archive.Entries
Dim fileName As String = Path.Combine(destinationDirectoryName, entry.FullName)
Directory.CreateDirectory(Path.GetDirectoryName(fileName))
Using inputStream As Stream = entry.Open()
Using outputStream As Stream = File.OpenWrite(fileName)
Dim progressStream As Stream = New StreamWithProgress(outputStream, Nothing,
New BasicProgress(Of Integer)(
Sub(i)
currentBytes += i
progress.Report(currentBytes / totalBytes)
End Sub))
inputStream.CopyTo(progressStream)
End Using
End Using
File.SetLastWriteTime(fileName, entry.LastWriteTime.LocalDateTime)
Next
End Using
End Sub
End Class
The .NET built-in implementation of IProgress(Of T) is intended for use in contexts where there is a UI thread where progress reporting events should be raised. As such, when used in a console program, like which I used to test this code, it will default to using the thread pool to raise the events, allowing for the possibility of out-of-order reports. To address this, the above uses a simpler implementation of IProgress(Of T), one that simply invokes the handler directly and synchronously.
BasicProgress.vb
Class BasicProgress(Of T)
Implements IProgress(Of T)
Private ReadOnly _handler As Action(Of T)
Public Sub New(handler As Action(Of T))
_handler = handler
End Sub
Private Sub Report(value As T) Implements IProgress(Of T).Report
_handler(value)
End Sub
End Class
And naturally, it's useful to have an example with which to test and demonstrate the code.
Module1.vb
Imports System.IO
Module Module1
Sub Main(args As String())
Dim sourceDirectory As String = args(0),
archive As String = args(1),
archiveDirectory As String = Path.GetDirectoryName(Path.GetFullPath(archive)),
unpackDirectoryName As String = Guid.NewGuid().ToString()
File.Delete(archive)
ZipFileWithProgress.CreateFromDirectory(sourceDirectory, archive,
New BasicProgress(Of Double)(
Sub(p)
Console.WriteLine($"{p:P2} archiving complete")
End Sub))
ZipFileWithProgress.ExtractToDirectory(archive, unpackDirectoryName,
New BasicProgress(Of Double)(
Sub(p)
Console.WriteLine($"{p:P0} extracting complete")
End Sub))
End Sub
End Module
Additional notes regarding this implementation can be found in my answer to the related question.
There is possibly a few things wrong with the below. Haven't had a chance to test/debug the code yet as can't run it. It stating that no main method has been found. But there is? i've even changed it to shared etc. It's probably something obvious?
It's flagging - 'Sub Main' was not found in 'ConsoleApplication1.Module1' error.
Also the main method wasn't always a separate class, I was just trying stuff. I'm importing a reference - system.processes. Was initially created as a vb.form but realised i didn't want the form part and recreated as a console app (which is very possibly where the problem lies as it's one of the first console apps i've done).
Code is basically planned to act on a service dying. Report and try and manage the restart (not finished, ideas welcome).
Imports System
Imports System.Management
Imports System.ServiceProcess
Imports System.Diagnostics
Imports System.Threading
Imports System.IO
Module Module1
Public Class Control
Public Sub Main() 'Public Sub Main(ByVal sArgs() As String)
Dim restart As New Rest
restart.startTime = DateTime.Now()
restart.cr20Services()
restart.Report()
End Sub
End Class
Public Class Rest
public startTime As String
Dim logPath As String = "C:\cr20\restart.txt"
'Dim fileExists As Boolean = File.Exists(strFile)
Dim arrcr20ServicesInitialStatus As New ArrayList
Dim failedServices As New ArrayList
Dim arrcr20Services As New ArrayList
Public Sub cr20Services()
'cr20 Services
arrcr20Services.Add("cr20 service")
arrcr20Services.Add("cr20 router")
For Each cr20Service In arrcr20Services
arrcr20ServicesInitialStatus.Add(cr20Service & " - " & cr20Status(cr20Service))
cr20Restore(cr20Service)
Next
End Sub
Private Function cr20Status(ByVal cr20Service As String)
Dim service As ServiceController = New ServiceController(cr20Service)
Return service.Status.ToString
End Function
Private Sub cr20Restore(ByVal cr20Service As String)
Dim service As ServiceController = New ServiceController(cr20Service)
'Dim p() As System.Diagnostics.Process = System.Diagnostics.Process.GetProcessesByName("calc")
If (service.Status.Equals(ServiceControllerStatus.Stopped)) Or (service.Status.Equals(ServiceControllerStatus.StopPending)) Then
failedServices.Add(service)
service.Stop()
Thread.Sleep(10000) 'give service 10 seconds to stop
service.Start()
End If
End Sub
In a contact manager program I've been storing data in CSV files for each contact and would like a way to compress this data into a single file.
I have attempted using data entry tools in the visual studio toolbox and template class, though I have never quite figured out how to use them. What would be especially convenient is if I could somehow store a generic class instance as opposed to having to come up with a string representation of it, and then parse it.
I'd also need to figure out how to tell the program what to do when a file is opened (I've noticed in the properties how to associate a file type with the program though am not sure how to tell it what to do when it's opened).
IMHO, switch to sqlite. You'll be able to query faster, compress it, and much more then working with a csv file.
Found this article about Serialization and it works very well!
http://www.vbdotnetheaven.com/UploadFile/Nimusoft/Serialization105022008052559AM/Serialization1.aspx
edit: Figured I should probably post more. I have a class IOwner, and list of this class contains all of my database. So I added serialization tags to this class and others it references then substitute in those properties with the ones shown on the article:
Imports System.Runtime.Serialization
Imports System.Runtime.Serialization.Formatters.Binary
Imports System.IO
Namespace BinarySerialization
<Serializable()> _
Public Class IFile
Implements ISerializable
Public Contacts As List(Of IOwner)
Public Self As IOwner
Public Cars As List(Of Vehicle)
Public path As String
Public Sub New()
End Sub
Public Sub New(ByVal info As SerializationInfo, ByVal context As StreamingContext)
Data.Self = info.GetValue("Self", GetType(IOwner))
Data.Contacts = info.GetValue("Contacts", GetType(List(Of IOwner)))
Data.Cars = info.GetValue("Cars", GetType(List(Of Vehicle)))
End Sub
Public Sub WriteFile()
Dim s As New FileStream(path, FileMode.Create, FileAccess.ReadWrite)
Dim B As New BinaryFormatter()
B.Serialize(s, Me)
s.Close()
End Sub
Public Function ReadFile() As IFile
Dim Fs As New FileStream(path, FileMode.Open, FileAccess.Read)
Dim F As New BinaryFormatter()
Dim s1 As IFile = DirectCast(F.Deserialize(Fs), IFile)
Fs.Close()
Return s1
End Function
#Region "ISerializable Members"
Public Sub GetObjectData(ByVal info As SerializationInfo, ByVal context As StreamingContext) Implements ISerializable.GetObjectData
info.AddValue("Self", Data.Self)
info.AddValue("Contacts", Data.Contacts)
info.AddValue("Cars", Data.Cars)
End Sub
#End Region
End Class
End Namespace
UPDATE 2016
Binary serialization is not advisable for complex structures that are subject to change. Using a database storage method such as SQLite and using an ODB (object database model) would have been preferable.