VB.NET中使用FTP下载文件的两种方法
.net没有专门处理FTP的类,我们可以通过调用系统自带的FTP.EXE 或者是调用win32 API中的wininet.dll来完成基本操作。希望以下的代码能为大家抛砖引玉。
方法一: 使用Ftp.exe ,通过process类来调用它。
Imports System.Diagnostics
...
? Public Sub GetFileByCallFtp()
?????? '定义ProcessStartInfo,Process的启动信息。
??????? Dim psi As New ProcessStartInfo
??????? 'ftp.exe的路径最好放到配置文件里。
??????? psi.FileName = "C:\WINNT\system32\ftp.exe"
??????? psi.RedirectStandardInput = False
??????? psi.RedirectStandardOutput = True
??????? '该值指示不使用操作系统Shell程序启动进程。
??????? psi.UseShellExecute = False
??????? '命令集文件名.注意,路径中不能有空格.
??????? Dim fileName As String = "C\ftp.txt"???
??????? '-s:FileName表示,从文件中读取控制命令
??????? psi.Arguments = "-s:" + fileName
??????? Dim proc As Process
??????? proc = Process.Start(psi)
??????? '等待进程完成任务
??????? proc.WaitForExit()
??????? '在控制台输出结果
??????? Console.WriteLine(proc.StandardOutput)
??????? Console.ReadLine()
??? End Sub
方法二,使用win32 api —— wininet.dll
首先是,api声明:
?? 因为此测试程序,是VB.NET ConsoleApplication所以,api声明写在Module里,
?? 方法是静态的。所以没加Shared关键字, 这一点请大家注意。
??? <DllImport("wininet")> _
??? Public Function InternetOpen(ByVal sAgent As String, ByVal LAccessType As Integer, ByVal sProxyName As String, _
????????????????????????????????? ByVal SProxyBypass As String, ByVal lFlags As Integer) As Integer
??? End Function
??? <DllImport("wininet")> _
??? Public Function InternetConnect(ByVal hInternetSession As Integer, ByVal sServerName As String, _
??????????????????????????????????? ByVal nServerPort As Integer, ByVal sUsername As String, _
??????????????????????????????????? ByVal sPassword As String, ByVal lService As Integer, _
??????????????????????????????????? ByVal lFlags As Integer, ByVal lContext As Integer) As Integer
??? End Function
??? <DllImport("wininet")> _
??? Public Function FtpGetFile(ByVal hFtpSession As Integer, ByVal lpszRemoteFile As String, _
?????????????????????????????? ByVal lpszNewFile As String, ByVal fFailIfExists As Boolean, _
?????????????????????????????? ByVal dwFlagsAndAttributes As Integer, ByVal dwFlags As Integer, _
?????????????????????????????? ByVal dwContext As Integer) As Boolean
??? End Function
??? <DllImport("wininet")> _
??? Public Function InternetCloseHandle(ByVal hInet As Integer) As Integer
??? End Function
??? 调用:
???? Public Sub GetFileByCallWininetDLL()
??????? Try
??????????? Dim intinet As Integer = InternetOpen(Nothing, 0, Nothing, Nothing, 0)
??????????? If intinet > 0 Then
??????????????? '参数:intinet的session值,ftp地址,端口,用户名,密码,lService, lFlags,lContext
??????????????? Dim intinetconn As Integer = InternetConnect(intinet, "192.168.110.152", 0, "tokiwa", "tokiwa", 1, 0, 0)
??????????????? If intinetconn > 0 Then
??????????????????? '下载某个文件到指定文件
??????????????????? Dim ret As Boolean = FtpGetFile(intinetconn, "pagerror.gif", "C:\itest.gif", 0, 0, 1, 0)
??????????????????? If ret Then
??????????????????????? Console.WriteLine("ok!")
??????????????????????? Console.ReadLine()
??????????????????? End If
??????????????????? InternetCloseHandle(intinetconn)
??????????????????? InternetCloseHandle(intinet)
??????????????? Else
??????????????????? Console.WriteLine("can't connect!")
??????????????????? Console.ReadLine()
??????????????? End If
??????????? Else
??????????????? Console.WriteLine("ftp wrong!")
??????????????? Console.ReadLine()
??????????? End If
??????? Catch ex As Exception
??????????? Console.WriteLine(ex.Message)
??????????? Console.ReadLine()
??????? End Try
??? End Sub