文件分割代码

Imports System.IO
''''
''Developed by : Sreenivas Vemulapalli  [email protected]
''Date :       08/10/2002
''Version: 1.0.0.0
''Description: To split the file into smaller chunks and merge them back to single file
''             Supports Multi threading /Thread safe 
''Remarks: Can be used to copy big file into floppies, copying file over network/internet
''  
''Future enhancements: Add Crypt and compression functionality
Public Class SplitMerge
    '''
    Private _FileName As String
    Private _ChunkSize As Integer
    Private _Error As String
    Private _OutPutPath As String
    Private _DeleteFileAfterSplit As Boolean
    Private _DeleteFilesAfterMerge As Boolean
    Public Event FileSplitCompleted(ByVal ErrorMessage As String)
    Public Event FileMergeCompleted(ByVal ErrorMessage As String)
    Public Event UpdateProgress(ByVal Progress As Double)
    '''
    Public Property DeleteFilesAfterMerge() As Boolean
        Get
            Return _DeleteFilesAfterMerge
        End Get
        Set(ByVal Value As Boolean)
            _DeleteFilesAfterMerge = Value
        End Set
    End Property
    '''
    Public Property DeleteFileAfterSplit() As Boolean
        Get
            Return _DeleteFileAfterSplit
        End Get
        Set(ByVal Value As Boolean)
            _DeleteFileAfterSplit = Value
        End Set
    End Property
    '''
    Public Property OutputPath() As String
        Get
            Return _OutPutPath
        End Get
        Set(ByVal Value As String)
            If Value.Length > 0 AndAlso Value.Substring(Value.Length - 1, 1) = "\" Then Value = Value.Substring(0, Value.Length - 1)
            _OutPutPath = Value
        End Set
    End Property
    '''
    Public ReadOnly Property getError() As String
        Get
            Return _Error
        End Get
    End Property
    '''
    Public Sub ClearErrors()
        _Error = ""
    End Sub
    '''
    Public Property FileName() As String
        Get
            Return _FileName
        End Get
        Set(ByVal Value As String)
            If Value <> "" Then
                If Value.Substring(Value.Length - 4, 4) = ".001" Then
                    _FileName = Value.Substring(0, Value.Length - 4)
                Else
                    _FileName = Value
                End If
            End If
        End Set
    End Property
    '''
    Public Property ChunkSize() As Integer
        Get
            Return _ChunkSize
        End Get
        Set(ByVal Value As Integer)
            _ChunkSize = Value
        End Set
    End Property
    '''
    Public Sub SplitFile()
        '''
        ''Usage
        '' Fille FileName and ChunkSize
        ''If output Folder is different than the input file then pass it, otherwise chunk files will be created in the
        '' same folder.
        ''Chunk File Size should be less than the input file size.
        ''Client application is informed via the FileSplitCompleted event
        ''Progress can be updated via UpdateProgress event
        Dim _FileSize As Long
        Dim _Index As Short
        Dim _OutputFile As String
        Dim _BaseName As String
        Dim _StartPosition As Long
        Dim _Buffer As Byte() = New Byte() {}
        Dim _InputFileStram As System.IO.FileStream
        Dim _OutputFileStram As System.IO.FileStream
        Dim _BinaryWriter As BinaryWriter
        Dim _BinaryReader As BinaryReader
        Dim _Fragments As Short
        Dim _RemainingBytes As Long
        Dim _SplitFileName As String
        Dim _Progress As Double
        '''
        Try
            _Error = ""
            _SplitFileName = Me.FileName
            _InputFileStram = New FileStream(FileName, FileMode.Open)
            _BinaryReader = New BinaryReader(_InputFileStram)
            _FileSize = FileSize(_SplitFileName)
            _BaseName = FileBaseName(_SplitFileName)
            If Not File.Exists(_SplitFileName) Then _Error = "File " & FileName & " doesn't exist"
            If _FileSize <= ChunkSize Then _Error = _SplitFileName & " size(" & _FileSize & ")  is less than the ChunkSize(" & ChunkSize & ")"
            If _Error = "" Then
                _Fragments = Math.Floor(_FileSize / ChunkSize)
                _Progress = 100 / _Fragments
                _RemainingBytes = _FileSize - (_Fragments * ChunkSize)
                If Me.OutputPath = "" Then Me.OutputPath = Directory.GetParent(_SplitFileName).ToString
                If Not Directory.Exists(Me.OutputPath) Then Directory.CreateDirectory(Me.OutputPath)
                _BinaryReader.BaseStream.Seek(0, SeekOrigin.Begin)
                For _Index = 1 To _Fragments
                    _OutputFile = Me.OutputPath & "\" & _BaseName & "." & Format(_Index, "000")
                    ReDim _Buffer(ChunkSize - 1)
                    _BinaryReader.Read(_Buffer, 0, ChunkSize)
                    _StartPosition = _BinaryReader.BaseStream.Seek(0, SeekOrigin.Current)
                    If File.Exists(_OutputFile) Then File.Delete(_OutputFile)
                    _OutputFileStram = New System.IO.FileStream(_OutputFile, FileMode.Create)
                    _BinaryWriter = New BinaryWriter(_OutputFileStram)
                    _BinaryWriter.Write(_Buffer)
                    _OutputFileStram.Flush()
                    _BinaryWriter.Close()
                    _OutputFileStram.Close()
                    RaiseEvent UpdateProgress(_Progress)
                Next
                If _RemainingBytes > 0 Then
                    _OutputFile = Me.OutputPath & "\" & _BaseName & "." & Format(_Index, "000")
                    ReDim _Buffer(_RemainingBytes - 1)
                    _BinaryReader.Read(_Buffer, 0, _RemainingBytes)
                    If File.Exists(_OutputFile) Then File.Delete(_OutputFile)
                    _OutputFileStram = New System.IO.FileStream(_OutputFile, FileMode.Create)
                    _BinaryWriter = New BinaryWriter(_OutputFileStram)
                    _BinaryWriter.Write(_Buffer)
                    _OutputFileStram.Flush()
                    _BinaryWriter.Close()
                    _OutputFileStram.Close()
                End If
                _InputFileStram.Close()
                _BinaryReader.Close()
                If Me.DeleteFileAfterSplit Then File.Delete(FileName)
                Me._Error = ""
            End If
        Catch ex As Exception
            Me._Error = ex.ToString
        Finally
            RaiseEvent UpdateProgress(100)
            RaiseEvent FileSplitCompleted(Me._Error)
            _BinaryWriter = Nothing
            _OutputFileStram = Nothing
            _BinaryReader = Nothing
            _InputFileStram = Nothing
        End Try
    End Sub
    '''
    Public Sub MergeFile()
        '''
        ''Usage
        '' Fille FileName and ChunkSize
        ''If output Folder is different than the input file then pass it, otherwise the merged file will be created in the
        '' same folder.
        ''Client application is informed via the FileMergeCompleted event
        ''Progress can be updated via UpdateProgress event

        Dim _InputFileStram As System.IO.FileStream
        Dim _OutputFileStram As System.IO.FileStream
        Dim _BinaryWriter As BinaryWriter
        Dim _BinaryReader As BinaryReader
        Dim _MergeFiles() As String
        Dim _index As Short
        Dim _buffer() As Byte = New Byte() {}
        Dim _FileSize As Long
        Dim _MergedFile As String
        Dim _MergingFileName As String
        Dim _Progress As Double
        Try
            _Error = ""
            _MergingFileName = Me.FileName
            If Me.FileName = "" Then _Error = "Merging File Name can't be empty"
            If _Error = "" Then
                _MergeFiles = getMergeFiles(_MergingFileName)
                _Progress = 100 / (_MergeFiles.Length - 1)
                If Not IsNothing(_MergeFiles) Then
                    If Me.OutputPath = "" Then Me.OutputPath = Directory.GetParent(_MergingFileName).ToString
                    If Not Directory.Exists(Me.OutputPath) Then Directory.CreateDirectory(Me.OutputPath)
                    _MergedFile = Me.OutputPath & "\" & FileBaseName(_MergingFileName)
                    If File.Exists(_MergedFile) Then File.Delete(_MergedFile)
                    _OutputFileStram = New FileStream(_MergedFile, FileMode.CreateNew)
                    _BinaryWriter = New BinaryWriter(_OutputFileStram)
                    For _index = 0 To _MergeFiles.Length - 1
                        _FileSize = FileSize(_MergeFiles(_index))
                        _InputFileStram = New FileStream(_MergeFiles(_index), FileMode.Open)
                        _BinaryReader = New BinaryReader(_InputFileStram)
                        _BinaryReader.BaseStream.Seek(0, SeekOrigin.Begin)
                        ReDim _buffer(_FileSize - 1)
                        _BinaryReader.Read(_buffer, 0, _buffer.Length)
                        _BinaryWriter.Write(_buffer)
                        _OutputFileStram.Flush()
                        _BinaryReader.Close()
                        _InputFileStram.Close()
                        RaiseEvent UpdateProgress(_Progress)
                    Next
                    _OutputFileStram.Close()
                    _BinaryWriter.Close()
                    If Me.DeleteFilesAfterMerge Then
                        For _index = 0 To _MergeFiles.Length - 1
                            File.Delete(_MergeFiles(_index))
                        Next
                    End If
                Else
                    _Error = "There are not merging files found in " & Me.OutputPath
                End If
            End If
        Catch ex As Exception
            Me._Error = ex.ToString
        Finally
            RaiseEvent UpdateProgress(100)
            RaiseEvent FileMergeCompleted(Me._Error)
            _OutputFileStram = Nothing
            _BinaryWriter = Nothing
            _BinaryReader = Nothing
            _InputFileStram = Nothing
        End Try
    End Sub
    '''
    Public Function FileSize(ByVal FileName As String) As Long
        Dim _fileInfo As System.IO.FileInfo
        _fileInfo = New FileInfo(FileName)
        Return _fileInfo.Length
        _fileInfo = Nothing
    End Function
    '''
    Private Function FileBaseName(ByVal FileName As String) As String
        Dim _fileInfo As System.IO.FileInfo
        _fileInfo = New FileInfo(FileName)
        Return _fileInfo.Name
        _fileInfo = Nothing
    End Function
    '''
    Private Function getMergeFiles(ByVal MergeFileName As String) As String()
        Dim _tempFiles As String() = System.IO.Directory.GetFiles(System.IO.Directory.GetParent(MergeFileName).ToString)
        Dim _MergeFiles() As String
        Dim _Index As Short
        Do
            _Index += 1
            If Array.BinarySearch(_tempFiles, MergeFileName & "." & Format(_Index, "000")) >= 0 Then
                ReDim Preserve _MergeFiles(_Index - 1)
                _MergeFiles(_Index - 1) = MergeFileName & "." & Format(_Index, "000")
            Else
                Exit Do
            End If
        Loop
        Return _MergeFiles
    End Function
    '''
End Class
'''