Imports Microsoft.VisualBasic
Imports System.Net
Imports System.Security.Cryptography.X509Certificates
Imports System.Security.Authentication
Imports System.Net.Security
Imports System.Collections.Generic
Imports System.Text
Imports System.IO
Public Class HttpUpload
Public Function GetWebRequest(ByVal url As String, ByVal method As String) As HttpWebRequest
Dim req As HttpWebRequest = Nothing
If url.Contains("https") Then
ServicePointManager.ServerCertificateValidationCallback = New RemoteCertificateValidationCallback(AddressOf CheckValidationResult)
req = CType(WebRequest.CreateDefault(New Uri(url)), HttpWebRequest)
Else
req = CType(WebRequest.Create(url), HttpWebRequest)
End If
req.ServicePoint.Expect100Continue = False
req.Method = method
req.KeepAlive = True
req.UserAgent = "Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/34.0.1847.116 Safari/537.36"
Return req
End Function
Public Function CheckValidationResult(ByVal sender As Object, ByVal certificate As X509Certificate, ByVal chain As X509Chain, ByVal errors As SslPolicyErrors) As Boolean
Return True
End Function
‘‘‘ <summary>
‘‘‘ 上传文件
‘‘‘ </summary>
‘‘‘ <param name="url"></param>
‘‘‘ <param name="textParams"></param>
‘‘‘ <param name="filename"></param>
‘‘‘ <param name="filestream"></param>
‘‘‘ <returns></returns>
‘‘‘ <remarks></remarks>
Public Function UploadFile(ByVal url As String, ByVal textParams As Dictionary(Of String, String), ByVal filename As String, ByVal filestream As System.IO.Stream) As String
Dim boundary As String = DateTime.Now.Ticks.ToString("X") ‘ 随机分隔线
Dim req As HttpWebRequest = GetWebRequest(url, "POST")
req.ContentType = "multipart/form-data;charset=utf-8;boundary=" + boundary
Dim reqStream As System.IO.Stream = req.GetRequestStream()
Dim itemBoundaryBytes As Byte() = Encoding.UTF8.GetBytes(vbCrLf & "--" & boundary & vbCrLf)
Dim endBoundaryBytes As Byte() = Encoding.UTF8.GetBytes(vbCrLf & "--" & boundary & "--" & vbCrLf)
‘ 组装文本请求参数
If Not IsNothing(textParams) Then
Dim textTemplate As String = "Content-Disposition:form-data;name=""{0}""" & vbCrLf & "Content-Type:text/plain" & vbCrLf & vbCrLf & "{1}"
For Each kvp As KeyValuePair(Of String, String) In textParams
Dim textEntry As String = String.Format(textTemplate, kvp.Key, kvp.Value)
Dim textBytes As Byte() = Encoding.UTF8.GetBytes(textEntry)
reqStream.Write(itemBoundaryBytes, 0, itemBoundaryBytes.Length)
reqStream.Write(textBytes, 0, textBytes.Length)
Next
End If
‘ 组装文件请求参数
Dim fileTemplate As String = "Content-Disposition:form-data;name=""{0}"";filename=""{1}""" & vbCrLf & "Content-Type:{2}" & vbCrLf & vbCrLf
Dim fileEntry As String = String.Format(fileTemplate, "file", filename, "application/octet-stream")
Dim itemBytes As Byte() = Encoding.UTF8.GetBytes(fileEntry)
reqStream.Write(itemBoundaryBytes, 0, itemBoundaryBytes.Length)
reqStream.Write(itemBytes, 0, itemBytes.Length)
Dim fileBytes As Byte() = New Byte(filestream.Length) {}
filestream.Read(fileBytes, 0, fileBytes.Length) ‘把文件流读入字节数组
filestream.Close()
reqStream.Write(fileBytes, 0, fileBytes.Length) ‘上传字节数组
reqStream.Write(endBoundaryBytes, 0, endBoundaryBytes.Length) ‘结尾标志
reqStream.Close()
Dim rsp As HttpWebResponse = CType(req.GetResponse(), HttpWebResponse)
Return GetResponseAsString(rsp, Encoding.UTF8)
End Function
‘‘‘ <summary>
‘‘‘ 把响应流转换为文本。
‘‘‘ </summary>
‘‘‘ <param name="rsp"></param>
‘‘‘ <param name="encoding"></param>
‘‘‘ <returns></returns>
‘‘‘ <remarks></remarks>
Public Function GetResponseAsString(ByVal rsp As HttpWebResponse, ByVal encoding As Encoding) As String
Dim stream As System.IO.Stream = Nothing
Dim reader As StreamReader = Nothing
Try
‘ 以字符流的方式读取HTTP响应
stream = rsp.GetResponseStream()
reader = New StreamReader(stream, encoding)
Return reader.ReadToEnd()
Catch ex As Exception
Finally
‘ 释放资源
If Not IsNothing(reader) Then reader.Close()
If Not IsNothing(stream) Then stream.Close()
If Not IsNothing(rsp) Then rsp.Close()
End Try
Return String.Empty
End Function
End Class
原文：http://my.oschina.net/zhuzhufanli/blog/294652