基于C#实现TCP/UDP通信及文件传输

一、TCP通信实现

1. 服务器端（文件传输）

using System;
using System.IO;
using System.Net;
using System.Net.Sockets;
using System.Threading;public class TcpFileServer {private const int Port = 12345;private const string BufferSize = 8192;public static void Start() {using (TcpListener listener = new TcpListener(IPAddress.Any, Port)) {listener.Start();Console.WriteLine($"服务器已启动，等待连接...");using (TcpClient client = listener.AcceptTcpClient())using (NetworkStream stream = client.GetStream()) {// 接收文件信息byte[] fileInfo = new byte[1024];int bytesRead = stream.Read(fileInfo, 0, fileInfo.Length);string fileName = Encoding.UTF8.GetString(fileInfo, 0, bytesRead).TrimEnd('\0');// 接收文件数据using (FileStream fs = new FileStream($"received_{fileName}", FileMode.Create)) {byte[] buffer = new byte[BufferSize];int totalBytes = 0;while ((bytesRead = stream.Read(buffer, 0, buffer.Length)) > 0) {fs.Write(buffer, 0, bytesRead);totalBytes += bytesRead;Console.WriteLine($"已接收: {totalBytes}字节");}}}}}
}

2. 客户端（文件传输）

public class TcpFileClient {public static void SendFile(string filePath, string serverIp) {using (TcpClient client = new TcpClient(serverIp, 12345))using (NetworkStream stream = client.GetStream()) {// 发送文件信息byte[] fileName = Encoding.UTF8.GetBytes(Path.GetFileName(filePath));stream.Write(fileName, 0, fileName.Length);// 发送文件数据using (FileStream fs = new FileStream(filePath, FileMode.Open)) {byte[] buffer = new byte[8192];int bytesRead;while ((bytesRead = fs.Read(buffer, 0, buffer.Length)) > 0) {stream.Write(buffer, 0, bytesRead);}}}}
}

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二、UDP通信实现

1. 实时数据传输（无连接）

public class UdpRealTime {private const int Port = 54321;private static UdpClient udpServer = new UdpClient(Port);public static void Start() {IPEndPoint remoteEP = new IPEndPoint(IPAddress.Any, 0);Console.WriteLine("UDP服务器已启动...");while (true) {byte[] received = udpServer.Receive(ref remoteEP);string message = Encoding.UTF8.GetString(received);Console.WriteLine($"收到来自 {remoteEP}: {message}");// 回显响应udpServer.Send(Encoding.UTF8.GetBytes("ACK"), 3, remoteEP);}}
}// 客户端
public class UdpClientApp {public static void Send(string message, string serverIp) {using (UdpClient client = new UdpClient()) {IPEndPoint remoteEP = new IPEndPoint(IPAddress.Parse(serverIp), 54321);byte[] data = Encoding.UTF8.GetBytes(message);client.Send(data, data.Length, remoteEP);// 接收回显IPEndPoint sendEP = new IPEndPoint(IPAddress.Any, 0);byte[] response = client.Receive(ref sendEP);Console.WriteLine($"服务器响应: {Encoding.UTF8.GetString(response)}");}}
}

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三、文件传输增强方案

1. 断点续传支持

// 服务器端扩展
public class ResumableTcpServer {public static void ResumeTransfer(TcpClient client) {using (NetworkStream stream = client.GetStream()) {// 获取已传输字节数byte[] resumeInfo = new byte[8];stream.Read(resumeInfo, 0, 8);long startPosition = BitConverter.ToInt64(resumeInfo, 0);// 从断点处继续写入using (FileStream fs = new FileStream("resumed_file.dat", FileMode.Append)) {fs.Seek(startPosition, SeekOrigin.Begin);// 继续接收数据...}}}
}// 客户端扩展
public class ResumableTcpClient {public static void SendWithResume(string filePath) {FileInfo fi = new FileInfo(filePath);long fileSize = fi.Length;// 发送文件信息（含总大小）using (TcpClient client = new TcpClient("127.0.0.1", 12345)) {NetworkStream stream = client.GetStream();byte[] sizeBytes = BitConverter.GetBytes(fileSize);stream.Write(sizeBytes, 0, sizeBytes.Length);// 断点续传逻辑using (FileStream fs = new FileStream(filePath, FileMode.Open)) {fs.Seek(0, SeekOrigin.Begin); // 实际应用中需读取已传输位置byte[] buffer = new byte[8192];int bytesRead;while ((bytesRead = fs.Read(buffer, 0, buffer.Length)) > 0) {stream.Write(buffer, 0, bytesRead);}}}}
}

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四、协议对比与选型建议

特性	TCP	UDP
连接方式	面向连接	无连接
可靠性	保证送达、顺序、完整性	不保证
传输效率	较低（有握手和确认机制）	高（无额外开销）
适用场景	文件传输、Web服务	实时音视频、在线游戏、DNS查询
典型实现类	TcpListener/TcpClient	UdpClient

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五、安全增强措施

1. SSL/TLS加密

   using (SslStream sslStream = new SslStream(stream, false)) {SslStream.AuthenticateAsServer(serverCertificate);await sslStream.WriteAsync(encryptedData);
   }
   

2. 数据校验

   // 添加CRC32校验
   public byte[] AddChecksum(byte[] data) {using (var crc32 = new CRC32()) {byte[] checksum = crc32.ComputeHash(data);return checksum.Concat(data).ToArray();}
   }
   

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六、完整项目结构示例

SocketApp/
├── Server/
│   ├── TcpServer.cs
│   ├── UdpServer.cs
│   └── FileTransferHandler.cs
├── Client/
│   ├── TcpClient.cs
│   ├── UdpClient.cs
│   └── FileSender.cs
├── Common/
│   ├── ProtocolParser.cs
│   └── Security/
│       └── AesEncryption.cs
└── Tests/└── NetworkTests.cs

参考代码 socket通讯（tcp/udp/文件传输等） www.youwenfan.com/contentcsh/57550.html

七、调试与测试建议

1. 网络模拟工具

   • 使用WireShark抓包分析协议格式
   • 通过Clumsy模拟网络延迟/丢包

2. 单元测试示例

   [TestClass]
   public class NetworkTests {[TestMethod]public async Task TestTcpTransfer() {var server = new TcpServer();var client = new TcpClient();await server.Start();await client.SendFile("test.dat");Assert.IsTrue(File.Exists("received_test.dat"));}
   }