VB.NET/C#批量上传文件至服务器的最优方案探讨

场景说明 #

我们有一个uploads.aspx页面，包含名为“Files To Upload”的多行文本框和“Upload”按钮。用户可在文本框中粘贴本地文件路径，示例如下：

/pages/contact-us.aspx
/pages/contact-us.aspx.vb
/App_Code/Contact/contact.vb
/pages/css/contact.css
/pages/css/contact2.css

核心问题：使用VB.NET/C#实现这些文件的上传，最优方式是FTP还是HTTP？目前很多旧代码示例已被弃用或不推荐，需要基于当前.NET规范的方案。

方案对比与推荐实现 #

1. HTTP上传：优先推荐（现代.NET首选） #

.NET官方已弃用HttpWebRequest、WebClient等旧API，当前推荐使用HttpClient，这是跨.NET Framework、.NET Core/.NET 5+的统一HTTP客户端，支持异步、连接池、现代HTTP特性。

实现思路

1. 读取文本框中的所有文件路径，验证文件存在性
2. 使用HttpClient构建MultipartFormDataContent，将文件添加到请求中
3. 发送POST请求到接收文件的HTTP接口

C# 示例代码

using System;
using System.IO;
using System.Net.Http;
using System.Threading.Tasks;
using System.Web.UI;

public partial class uploads : Page
{
    private static readonly HttpClient _httpClient = new HttpClient();

    protected async void UploadButton_Click(object sender, EventArgs e)
    {
        var filePaths = FilesToUpload.Text.Split(new[] { Environment.NewLine }, StringSplitOptions.RemoveEmptyEntries);
        var content = new MultipartFormDataContent();

        foreach (var path in filePaths)
        {
            var fullPath = Server.MapPath(path); // 若路径是站点相对路径，转换为物理路径
            if (!File.Exists(fullPath)) continue;

            var fileStream = File.OpenRead(fullPath);
            content.Add(new StreamContent(fileStream), "files", Path.GetFileName(fullPath));
        }

        try
        {
            // 替换为目标HTTP接收接口地址
            var response = await _httpClient.PostAsync("https://your-target-server/upload", content);
            response.EnsureSuccessStatusCode();
            // 处理上传成功逻辑
        }
        catch (HttpRequestException ex)
        {
            // 处理异常
        }
    }
}

VB.NET 示例代码

Imports System
Imports System.IO
Imports System.Net.Http
Imports System.Threading.Tasks
Imports System.Web.UI

Partial Class uploads
    Inherits Page

    Private Shared ReadOnly _httpClient As New HttpClient()

    Protected Async Sub UploadButton_Click(sender As Object, e As EventArgs) Handles UploadButton.Click
        Dim filePaths = FilesToUpload.Text.Split({Environment.NewLine}, StringSplitOptions.RemoveEmptyEntries)
        Dim content = New MultipartFormDataContent()

        For Each path In filePaths
            Dim fullPath = Server.MapPath(path) ' 转换站点相对路径为物理路径
            If Not File.Exists(fullPath) Then Continue For

            Dim fileStream = File.OpenRead(fullPath)
            content.Add(New StreamContent(fileStream), "files", Path.GetFileName(fullPath))
        Next

        Try
            ' 替换为目标HTTP接收接口地址
            Dim response = Await _httpClient.PostAsync("https://your-target-server/upload", content)
            response.EnsureSuccessStatusCode()
            ' 处理上传成功逻辑
        Catch ex As HttpRequestException
            ' 处理异常
        End Try
    End Sub
End Class

2. FTP上传：仅当目标服务器仅支持FTP时使用 #

.NET官方已将FtpWebRequest标记为过时，不再推荐使用原生API。如果必须使用FTP，优先选择第三方成熟库，比如WinSCP.NET或Flurl.Http，这些库维护更活跃，支持现代FTP特性（如FTPS、SFTP）。

基于WinSCP.NET的示例（C#）

using WinSCP;

protected void UploadButton_Click(object sender, EventArgs e)
{
    var filePaths = FilesToUpload.Text.Split(new[] { Environment.NewLine }, StringSplitOptions.RemoveEmptyEntries);
    var sessionOptions = new SessionOptions
    {
        Protocol = Protocol.Ftp,
        HostName = "your-ftp-server",
        UserName = "ftp-user",
        Password = "ftp-password"
    };

    using (var session = new Session())
    {
        session.Open(sessionOptions);
        foreach (var path in filePaths)
        {
            var fullPath = Server.MapPath(path);
            if (!File.Exists(fullPath)) continue;

            // 上传到FTP服务器的目标路径，需根据实际情况调整
            session.PutFiles(fullPath, "/remote-target-folder/*").Check();
        }
    }
}

方案选择建议 #

• 优先选HTTP：如果目标服务器提供HTTP/HTTPS文件接收接口，HttpClient是现代.NET的标准方案，API简洁、性能优异，且无过时风险。
• 仅用FTP：仅当目标服务器只支持FTP协议时使用，务必选择第三方库替代过时的FtpWebRequest，避免后续.NET版本兼容性问题。

内容的提问来源于stack exchange，提问作者user1946932