如何使用 vb.NET 从 URL 读取 XML 数据并保存

Question

朋友们，我能够通过单个字节获取 XML 文件，也许这遇到了一些问题。您可以建议我使用替代方法来执行相同的操作来保存 XML 文件吗？

  Try
        Dim strUrl As String = "http://example.com" 
        Dim wr As HttpWebRequest = CType(WebRequest.Create(strUrl), HttpWebRequest)
        Dim ws As HttpWebResponse = CType(wr.GetResponse(), HttpWebResponse)
        ws.ContentType = "UTF-16"
        Dim str As Stream = ws.GetResponseStream()
        Dim inBuf(100000) As Byte
        Dim bytesToRead As Integer = CInt(inBuf.Length)
        Dim bytesRead As Integer = 0
        While bytesToRead > 0
            Dim n As Integer = str.Read(inBuf, bytesRead, bytesToRead)
            If n = 0 Then
                Exit While
            End If
            bytesRead += n
            bytesToRead -= n
        End While
        Dim fstr As New FileStream("c:/GetXml.xml", FileMode.OpenOrCreate, FileAccess.Write)
        fstr.Write(inBuf, 0, bytesRead)
        str.Close()
        fstr.Close()
    Catch ex As WebException
        Response.Write(ex.Message)
    End Try

Answer 1

为什么不直接使用 WebClient 类及其 DownloadFile 方法？看起来容易多了......

这是用 C# 编写的，但是将其转换为 VB.NET 应该没有问题：

WebClient wc = new WebClient();
wc.DownloadFile("http://xyz", @"C:\getxml.xml");

然后就完成了！

马克

Answer 2

考虑使用 XMLTextReader。此示例只是将整个 XML 加载到字符串中，但显然您可以将其写入文件：

    Dim strUrl As String = "http://xyz.com"
    Dim reader As XmlTextReader = New XmlTextReader(strUrl)
    Dim output as String

    Do While (reader.Read())
        Select Case reader.NodeType
            Case XmlNodeType.Element 

                Output = Output + "<" + reader.Name

                If reader.HasAttributes Then 
                    While reader.MoveToNextAttribute()
                        Output = Output + " {0}='{1}'", reader.Name, reader.Value)
                    End While
                End If
                Output = Output + ">"
            Case XmlNodeType.Text
                Output = Output + reader.Value
            Case XmlNodeType.EndElement
                Output = Output + "</" + reader.Name + ">"
        End Select
    Loop

Answer 3

如果服务将请求发送到我们的 URL 怎么办？我如何调整它来读取他们发送的http流？经历了这么艰难的时光......（我应该做一个单独的线程吗？抱歉。）