WebRequest保持Session和Cookie

最近用到了webrequest,查了很多资料都无法保存网站的登录信息

最后自己终于调试成功了一把。

Option   Explicit   On  
Option   Strict   On

Imports  System.Net
Imports  System.Web
Imports  System.Text
Imports  System.IO

Namespace SoilNET Namespace SoilNET.KRL.WebUtility

    Public Class LoginRequestClass LoginRequest
        Public Cookies As CookieCollection


        Sub New()Sub New()

        End Sub
        Public Function Login()Function Login(ByVal Url As String, ByVal Params As String) As String
            Dim strResult As String = getPageByPost(Url, Params)
            Return strResult
        End Function

        Public Function getPageByPost()Function getPageByPost(ByVal url As String, ByVal payload As String, Optional ByVal needEncode As Boolean = False) As String
            Dim result As HttpWebResponse
            Dim strResult As String = 
            Try
                Dim req As HttpWebRequest
                Dim RequestStream As Stream
                Dim ReceiveStream As Stream
                Dim encode As Encoding
                Dim sr As StreamReader

                req = CType(WebRequest.Create(url), HttpWebRequest)
                req.Method = POST
                req.ContentType = applicationx-www-form-urlencoded
                req.CookieContainer = New CookieContainer
                req.UserAgent = Mozilla4.0 (compatible; MSIE 6.0; Windows NT 5.0; Q312461; .NET CLR 1.0.3705)

                If Not Me.Cookies Is Nothing Then
                    req.CookieContainer.Add(New Uri(url), Me.Cookies)
                End If


                Dim SomeBytes() As Byte
                Dim UrlEncoded As New StringBuilder
                Dim reserved() As Char = {ChrW(63), ChrW(61), ChrW(38)}

                If payload  Nothing Then
                    If needEncode Then '有些网站encode后反而出现中文乱码所以加上这个开关
                        Dim i As Integer = 0
                        Dim j As Integer
                        While i  payload.Length
                            j = payload.IndexOfAny(reserved, i)
                            If j = -1 Then
                                UrlEncoded.Append(HttpUtility.UrlEncode(payload.Substring(i, payload.Length - i)))
                                Exit While
                            End If
                            UrlEncoded.Append(HttpUtility.UrlEncode(payload.Substring(i, j - i)))
                            UrlEncoded.Append(payload.Substring(j, 1))
                            i = j + 1
                        End While
                        SomeBytes = System.Text.Encoding.ASCII.Default.GetBytes(UrlEncoded.ToString())
                    Else
                        SomeBytes = System.Text.Encoding.ASCII.Default.GetBytes(payload)
                    End If
                    req.ContentLength = SomeBytes.Length
                    RequestStream = req.GetRequestStream()
                    RequestStream.Write(SomeBytes, 0, SomeBytes.Length)
                    RequestStream.Close()
                Else
                    req.ContentLength = 0
                End If
                'result.Cookies = New CookieCollection
                result = CType(req.GetResponse(), HttpWebResponse)


                ReceiveStream = result.GetResponseStream()
                encode = System.Text.Encoding.ASCII.Default
                sr = New StreamReader(ReceiveStream, encode)

                Dim read(256) As Char
                Dim count As Integer = sr.Read(read, 0, 256)

                Do While count  0
                    strResult &= New String(read, 0, count)
                    count = sr.Read(read, 0, 256)
                Loop
                Me.Cookies = req.CookieContainer.GetCookies(New Uri(url))

            Catch Exc As Exception

                Debug.Write(Exc.Message)
            Finally

                If Not result Is Nothing Then
                    result.Close()
                End If

            End Try
            Return strResult
        End Function
        Public Function getPageByUrl()Function getPageByUrl(ByVal url As String) As String
            Dim result As HttpWebResponse
            Dim strResult As String = 
            Try
                Dim req As HttpWebRequest

                Dim ReceiveStream As Stream
                Dim encode As Encoding
                Dim sr As StreamReader

                req = CType(WebRequest.Create(url), HttpWebRequest)

                req.Method = GET

                req.CookieContainer = New CookieContainer
                req.UserAgent = Mozilla4.0 (compatible; MSIE 6.0; Windows NT 5.0; Q312461; .NET CLR 1.0.3705)

                If Not Me.Cookies Is Nothing Then
                    req.CookieContainer.Add(New Uri(url), Me.Cookies)
                End If

                result = CType(req.GetResponse(), HttpWebResponse)


                ReceiveStream = result.GetResponseStream()
                encode = System.Text.Encoding.ASCII.Default
                sr = New StreamReader(ReceiveStream, encode)

                Dim read(256) As Char
                Dim count As Integer = sr.Read(read, 0, 256)

                Do While count  0
                    strResult &= New String(read, 0, count)
                    count = sr.Read(read, 0, 256)
                Loop
                Me.Cookies = req.CookieContainer.GetCookies(New Uri(url))
            Catch Exc As Exception


            Finally

                If Not result Is Nothing Then
                    result.Close()
                End If

            End Try
            Return strResult
        End Function
    End Class
End Namespace