用C#的HttpListener获取formdata的示例代码

以下是使用C#的HttpListener获取formdata的示例代码：

using System;
using System.IO;
using System.Net;
using System.Text;

namespace HttpListenerExample
{
    class Program
    {
        static void Main(string[] args)
        {
            string url = "http://localhost:8080/";
            HttpListener listener = new HttpListener();
            listener.Prefixes.Add(url);
            listener.Start();
            Console.WriteLine("Listening on " + url);

            while (true)
            {
                HttpListenerContext context = listener.GetContext();
                HttpListenerRequest request = context.Request;
                HttpListenerResponse response = context.Response;

                if (request.HttpMethod == "POST")
                {
                    // Check if the request is sending form data
                    if (request.ContentType.StartsWith("multipart/form-data"))
                    {
                        string boundary = request.ContentType.Substring("multipart/form-data; boundary=".Length);
                        byte[] boundaryBytes = Encoding.UTF8.GetBytes("--" + boundary + "\r\n");

                        string formFieldName = null;
                        string formFieldValue = null;
                        using (Stream bodyStream = request.InputStream)
                        {
                            byte[] buffer = new byte[4096];
                            int bytesRead;
                            while ((bytesRead = bodyStream.Read(buffer, 0, buffer.Length)) > 0)
                            {
                                int start = 0;
                                int end = bytesRead;

                                // Check if the buffer contains the boundary
                                for (int i = 0; i < bytesRead; i++)
                                {
                                    if (buffer[i] == boundaryBytes[0] && bytesRead - i >= boundaryBytes.Length)
                                    {
                                        bool found = true;
                                        for (int j = 1; j < boundaryBytes.Length; j++)
                                        {
                                            if (buffer[i + j] != boundaryBytes[j])
                                            {
                                                found = false;
                                                break;
                                            }
                                        }

                                        if (found)
                                        {
                                            end = i;
                                            break;
                                        }
                                    }
                                }

                                // Process the buffer
                                if (formFieldName == null)
                                {
                                    // Find the form field name
                                    string bufferStr = Encoding.UTF8.GetString(buffer, start, end - start);
                                    int nameStartIndex = bufferStr.IndexOf("name=\"");
                                    if (nameStartIndex != -1)
                                    {
                                        int nameEndIndex = bufferStr.IndexOf("\"", nameStartIndex + "name=\"".Length);
                                        if (nameEndIndex != -1)
                                        {
                                            formFieldName = bufferStr.Substring(nameStartIndex + "name=\"".Length, nameEndIndex - (nameStartIndex + "name=\"".Length));
                                        }
                                    }
                                }
                                else
                                {
                                    // Find the form field value
                                    string bufferStr = Encoding.UTF8.GetString(buffer, start, end - start);
                                    formFieldValue += bufferStr;
                                }

                                // Check if the buffer contains the end boundary
                                if (end + boundaryBytes.Length < bytesRead && buffer[end + boundaryBytes.Length] == '-')
                                {
                                    // End of form data
                                    break;
                                }
                            }
                        }

                        Console.WriteLine("Form field name: " + formFieldName);
                        Console.WriteLine("Form field value: " + formFieldValue);

                        // Send response
                        string responseString = "Form field name: " + formFieldName + "\r\nForm field value: " + formFieldValue;
                        byte[] responseBytes = Encoding.UTF8.GetBytes(responseString);
                        response.ContentType = "text/plain";
                        response.ContentLength64 = responseBytes.Length;
                        response.OutputStream.Write(responseBytes, 0, responseBytes.Length);
                    }
                }

                response.Close();
            }
        }
    }
}

此代码演示了如何使用HttpListener来监听HTTP请求，并从POST请求中获取formdata。此代码支持处理包含多个字段的表单数据，并将每个字段的名称和值输出到控制台。此外，它还发送一个简单的响应，包含从表单数据中提取的字段名称和值。