从 url 保存图像

Question

是否可以使用Visual Basic 2008 从 URL 将图像保存到我的 PC？

例如：从www.domain.com/image.jpg到C:\folder\image.jpg

P.S：我需要最简单的代码示例，然后我将根据需要进行编辑。

谢谢。

更新：我想知道代码何时完成图像下载。

Answer 1

创建一个模块并使用这个函数

公开声明函数 ShellExecute Lib "shell32.dll" 别名 "ShellExecuteA" (ByVal hwnd As Long, ByVal lpOperation As String, ByVal lpFile As String, ByVal lpParameters As String, ByVal lpDirectory As String, ByVal nShowCmd As Long) As Long Private Declare Function URLDownloadToFile Lib "urlmon" Alias "URLDownloadToFileA" (ByVal pCaller As Long, ByVal szURL As String, ByVal szFileName As String, ByVal dwReserved As Long, ByVal lpfnCB As Long) As Long

公共函数 DownloadFile(sURLFile As String, sLocalFilename As String) As Boolean 调暗 lRetVal 只要 lRetVal = URLDownloadToFile(0, sURLFile, sLocalFilename, 0, 0) 如果 lRetVal = 0 那么 DownloadFile = True 结束函数

Answer 2

这是我想出的。

 Public Function getImgFrmUrl(ByVal url As String, ByVal Optional ImageName As String = "", ByVal Optional DstntnPath As String = "c:\") As String

        Dim imgPath = DstntnPath & "\"
        Dim name = IIf(ImageName.Length = 0, Guid.NewGuid.ToString, ImageName)
        Dim fileExt = Path.GetExtension(url)

        Using webClient As WebClient = New WebClient
            Const _Tls12 As SslProtocols = CType(&HC00, SslProtocols)
            Const Tls12 As SecurityProtocolType = CType(_Tls12, SecurityProtocolType)
            ServicePointManager.SecurityProtocol = Tls12
            Dim data As Byte() = webClient.DownloadData(url)
            If File.Exists(imgPath + name & fileExt) Then File.Delete(imgPath + name & fileExt)

            Using mem = New MemoryStream(data)

                Using yourImage = Image.FromStream(mem)

                    If fileExt.ToLower Is ".png" Then
                        yourImage.Save(imgPath + name & fileExt, ImageFormat.Png)
                    Else
                        yourImage.Save(imgPath + name & fileExt, ImageFormat.Jpeg)
                    End If
                End Using
            End Using
        End Using

        Return imgPath & name & fileExt
    End Function

Answer 3

这是我知道的最简单的方法。

Dim Client as new WebClient
Client.DownloadFile(Source, Destination)
Client.Dispose

这优于使用 Microsoft 的 documentation 中的 My.Computer.Network.DownloadFile 方法

“DownloadFile 方法不发送可选的 HTTP 标头。如果可选的用户代理标头丢失，某些服务器可能会返回 500（内部服务器错误）。要发送可选标头，您必须使用 WebClient 类构造一个请求。”

Answer 4

有一个更简单的方法：

My.Computer.Network.DownloadFile(Source, Desination)