mydownthread.vb

编程环境VB.NET2005 多线程下载

Imports System.Threading
Public Class MyDownThread
#Region "dim"
    Private m_filename As String
    Private m_startPos As Long
    Private m_endPos As Long
    Private m_nowPos As Long
    Private m_url As String
    Friend m_speed As Long
    Private memDiskSize As Integer = 100000 * 100
    Private bufferSize As Integer = CInt(Me.memDiskSize / 100)
    Friend speedlimit As Boolean = True
    Friend limitspeedtime As Integer
    Private m_stop As Boolean = False
    Friend Event thStop(ByVal sender As MyDownThread, ByVal saveData As MyThreadStru)
    Private m_threadData As MyThreadStru
    '    Friend clearSpeedSum As Boolean '速度是否清空
    Friend writeCount As Integer
    Friend thisThNoErrStop As Boolean = False
    Friend thErrCount As Integer = 0
#End Region
    Public Property MyThreadData() As MyThreadStru
        Get
            m_threadData.startPos = Me.m_startPos
            m_threadData.nowPos = Me.m_nowPos
            m_threadData.endPos = Me.m_endPos
            m_threadData.speed = Me.m_speed
            Return m_threadData
        End Get
        Set(ByVal value As MyThreadStru)
            m_threadData = value
            Me.m_url = m_threadData.url
            Me.m_filename = m_threadData.filename
            Me.m_startPos = m_threadData.startPos
            Me.m_nowPos = m_threadData.nowPos
            Me.m_endPos = m_threadData.endPos
        End Set
    End Property
    Public Sub New(ByVal nt As MyThreadStru)
        Me.MyThreadData = nt
    End Sub
    Sub startdown()
        'If Me.MyThreadData.nowPos = (Me.MyThreadData.endPos - Me.MyThreadData.startPos + 1) Then
        '    RaiseEvent thStop(Me, Me.MyThreadData)
        '    Exit Sub
        'End If
        Me.m_stop = False
        System.Threading.Thread.Sleep(Me.thErrCount * 1000)
        Me.DoDownload()
        Exit Sub

        Dim th As Threading.Thread
        th = New Threading.Thread(AddressOf Me.DoDownload)
        th.Start()
    End Sub
    Sub stopDown()
        Me.m_stop = True
    End Sub

    Sub DoDownload()
        If Me.m_nowPos = Me.m_endPos + 1 Then
            Me.thisThNoErrStop = True
            RaiseEvent thStop(Me, Me.MyThreadData)
            Exit Sub
        End If
        '********************************************************
        'http://dugupiaoyun.icode.csdn.net/post/2007/06/21/54243
        Dim ns As System.IO.Stream = Nothing : Dim request As Net.HttpWebRequest
        Dim fs As New IO.FileStream(Me.m_filename, System.IO.FileMode.Open, IO.FileAccess.Write, IO.FileShare.ReadWrite)
        Dim b(bufferSize - 1) As Byte : Dim ret As Integer
        Dim memB(memDiskSize - 1) As Byte
        Try
            request = CType(Net.HttpWebRequest.Create(Me.m_url), Net.HttpWebRequest)
            '接收的起始位置及接收的长度
            request.AddRange(CInt(Me.m_nowPos), CInt(Me.m_endPos))
            ns = request.GetResponse.GetResponseStream
            fs.Seek(Me.m_nowPos, IO.SeekOrigin.Begin)
            Dim L As Integer = 0
            Do
                ret = ns.Read(b, 0, bufferSize)
                If L + ret >= memDiskSize Then '要超过时
                    fs.Write(memB, 0, L)
                    writeCount += 1
                    L = ret
                Else
                    L += ret
                End If
                Array.Copy(b, 0, memB, L - ret, ret)

                Me.m_speed += ret
                Me.m_nowPos += ret

                If Me.m_stop = True Then Exit Do
                If Me.speedlimit = True Then
                    'System.Threading.Thread.Sleep(limitspeedtime)
                End If

                'While speedlimit
                '    '    System.Threading.Thread.Sleep(100)
                '    If Me.m_stop = True Then Exit Do
                'End While
                'System.Threading.Thread.Sleep(200)

            Loop Until ret = 0
            fs.Write(memB, 0, L)
            writeCount += 1

            'ret = ns.Read(b, 0, bufferSize)
            'While ret > 0
            '    If Me.m_stop = True Then Exit While
            '    fs.Write(b, 0, ret)
            '     Me.m_speed += ret
            '    Me.m_nowPos += ret
            '    While speedlimit
            '        System.Threading.Thread.Sleep(10)
            '        If Me.m_stop = True Then Exit While
            '    End While
            '    ret = ns.Read(b, 0, bufferSize)
            'End While

            Me.m_speed = 0
            fs.Close()
            ns.Close()
            Me.thisThNoErrStop = True
            Me.thErrCount = 0
            RaiseEvent thStop(Me, Me.MyThreadData)
        Catch ex As Exception
            Me.thisThNoErrStop = False
            Me.thErrCount += 1
            RaiseEvent thStop(Me, Me.MyThreadData)
            Debug.WriteLine("出错:" & Me.MyThreadData.startPos.ToString & " time:" & Now.ToString & " : " & ex.Message)
        Finally
            If fs Is Nothing = False Then fs.Close()
            If ns Is Nothing = False Then ns.Close()
        End Try
    End Sub

  
End Class