Imports System.IO
Imports System.Net
Public Class Form1
Private Sub btnDown_Click(sender As Object, e As EventArgs) Handles btnDown.Click
Dim hwq As HttpWebRequest
Dim hwp As HttpWebResponse
Dim colHeader As WebHeaderCollection '响应头信息集合
Dim lngSize As Int64 '要下载文件的总大小
Dim lngCurSize As Int64 '已经下载大小
Dim lngNet As Int64 '计算网速用
Dim stRespones As Stream '响应流
Dim st As FileStream '本地流
Dim intCurSize As Int64
Dim bytBuffer(512) As Byte '缓存大小
Dim datLast As DateTime '最后一次时间
Dim intDiff As Int32 '两次时间差（秒）
datLast = Now '取得开始时间
hwq = CType(HttpWebRequest.Create(txtAddress.Text), HttpWebRequest) '请求对象创建
hwp = hwq.GetResponse '取得响应对象
colHeader = hwp.Headers '取得响应头
lngSize = colHeader.Get("Content-Length") '取得要下载文件的大小
stRespones = hwp.GetResponseStream '取得响应流
st = New FileStream("D:\2.zip", FileMode.Create) '本地保存文件
intCurSize = stRespones.Read(bytBuffer, 0, bytBuffer.Length) '响应流中读取
Do While (intCurSize > 0) '只要有数据就继续
st.Write(bytBuffer, 0, intCurSize) '写入本地文件
intDiff = DateDiff(DateInterval.Second, datLast, Now)
lngCurSize = lngCurSize + intCurSize
lngNet = lngNet + intCurSize '单位时间内的下载量
If intDiff >= 1 Then
txtState.Text = "文件大小：" & lngSize & vbCrLf &
"已经下载：" & lngCurSize & vbCrLf &
"下载速度：" & CInt(lngNet / intDiff / 1024) & "k/s" & vbCrLf &
"下载百分比：" & Math.Round(lngCurSize/lngSize*100, 2) & " %"
datLast = Now
lngNet = 0
End If
Application.DoEvents()
intCurSize = stRespones.Read(bytBuffer, 0, bytBuffer.Length) '继续读取
Loop
txtState.Text = "下载完成！"
st.Close()
stRespones.Close()
End Sub
End Class