局域网文件传输软件[通俗易懂]

大家好，又见面了，我是你们的朋友全栈君。在公司实习了一个周，虽然很累，但也感觉有所得，此次项目是做一个局域网两台计算机之间的文件传输。我用的主要控件为winsock控件，用其TCP协议。至于用此控件连接两台计算机书上都有介绍，我主要介绍一下我传送文件的思想和方法： 首先，将要传送的文件分成指定大小的N个包，大小不能超过8K因为TCP每次最多发送8K数据，最后一个包可能会小于其它包。然后在每个包加个包头，因为接收端需要通过包头知道传送过来的是数据还是路径（因为发送端指定存放路径），接收端收到数据后必须返回确认到发送端，这样才能循环发送，但一定要有最后的终止，不然会死循环。我的主要发送和接收代码如下： 发送端收到数据后产生的事件 Private Sub WskCli_DataArrival(ByVal bytesTotal As Long) Dim FIT As Boolean, OVER As Boolean, xx As Byte WskCli.GetData FIT If Number < BagNum Then If FIT = True Then ‘接收端已收到上一个数据包 If v <> 0 Then ‘传送速率受限制 Dim ss As Long ss = 0 Do Until (Number * 1024 <= v * ss) ‘传送速率过大则等待 ss = CLng((Time – timeInt) * 3600 * 24) Loop End If Send_File ‘调用发送文件数据包过程 End If Number = Number + 1 ‘计数 ProgressBar1.Value = Number * 20 / BagNum ‘刷新进度条的进度 El** *x = 2 WskCli.SendData xx ‘发送传送完毕的信息给接收端 Close 1 Label1.Caption = “发送完毕！” OVER = True Number = 0 ‘传送完后置计数Number=0 End If If OVER = True Then ‘传送完之后的处理 Drive1.Enabled = True Dir1.Enabled = True File1.Enabled = True CmdSend.Enabled = True Exit Sub End If End Sub send_file是自定义的一个发送过程: Private Sub Send_File() Dim i As Long ‘循环变量 If Number <= BagNum – 1 Then ReDim Buff(1 To BagSize) As Byte ‘定义缓冲区 ReDim TempBuff(0 To BagSize) As Byte Get 1, , Buff TempBuff(0) = 1 ‘设置包头为1代表文件数据 For i = 1 To BagSize TempBuff(i) = Buff(i) Next WskCli.SendData TempBuff Else ‘传送最后一个数据包 n = filelength – Seek(1) + 1 ‘得到最后一个包的大小 If n > 0 Then ReDim Buff(0 To n) As Byte ReDim TempBuff(0 To n) As Byte TempBuff(0) = 1 ‘设置包头为1代表文件数据 Get 1, , Buff For i = 1 To n TempBuff(i) = Buff(i – 1) Next WskCli.SendData TempBuff End If End If End Sub

‘发送按钮被按下的响应事件 Private Sub CmdSend_Click() CmdSend.Enabled = False Combo1.Enabled = False If Combo1.Text = “” Then MsgBox “请选择一个传输速度！”, vbOKOnly, “错误” Else ‘传送速度的选择 Select Case Combo1.ListIndex Case 0 v = CLng(200) * 1024 Case 1 v = CLng(600) * 1024 Case 2 v = 1.5 * CLng(1024) * 1024 Case 3 v = 2 * CLng(1024) * 1024 Case 4 v = 0 End Select If Number > 0 Then ‘重传或续传 If MsgBox(“上次未能传送完成，是否续传？”, vbYesNo, “提示”) = vbNo Then Number = 0: Close 1 End If ReDim Buff(Len(sendFileName)) As Byte Buff(0) = 0 For i = 1 To Len(sendFileName) Buff(i) = Asc(Mid(sendFileName, i, 1)) Next WskCli.SendData Buff ‘发送文件路径和文件名 End If Open fn For Binary Access Read As #1 ‘设置数据包的数量 filelength = LOF(1) ‘文件长度 BagNum = filelength / BagSize If BagNum < filelength / BagSize Then BagNum = BagNum + 1 ‘计时初始化 timeInt = Time

End Sub 接收端接收数据的事件： Private Sub WskSer_DataArrival(ByVal bytesTotal As Long) Dim Buff() As Byte ‘定义接收数据缓冲区 Dim OVER As Boolean ‘结束标记 WskSer.GetData Buff ‘接收数据 ‘判断包头信息 Select Case Buff(0) ‘包头 Case 0 ‘得到存放路径和文件名 fn = “” For i = 1 To UBound(Buff) fn = fn + Chr(Buff(i)) Next Open fn For Binary As #1 ‘新建或打开文件 Close 1 Label1.Caption = “正在发送” Case 1 ‘写入文件 Open fn For Binary Access Write As #1 Seek #1, LOF(1) + 1 ‘找到文件尾 ReDim TempBuff(1 To UBound(Buff)) As Byte ‘去掉包头 For i = 1 To UBound(Buff) TempBuff(i) = Buff(i) Next Put 1, , TempBuff ‘将数据写入文件 Close 1 Case 2 ‘接收结束 Label1.Caption = “发送完毕！” OVER = True End Select If OVER = True Then Exit Sub ‘如果接收完毕则退出此过程 WskSer.SendData True ‘告诉客户端继续发送下一个数据包 End Sub

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