说明：该程序可能不具备实用性，仅测试用。
一、使用虚拟串口工具VSPD虚拟两个串口COM1和COM2
二、约定
占一个字节，代码如下：
using System;using System.Collections.Generic;using System.Linq;using System.Text;namespace COMClient{ /// /// 约定 /// public enum Protocol { Client端发送文件名 = 0, Client端发送数据块 = 1, Client端发送最后一个数据块 = 2, Server端本次接收完毕 = 3, Server端结束 = 4 }} 三、功能说明：
COMClient程序监听COM1串口，COMServer程序监听COM2串口。COMClient先择文件，发送，COMServer接收文件。数据分多次发送，每次发送的数据，通过第一个字节判断发送的这段数据是干啥的，后面的字节是数据本身。
四、COMClient端发送文件
代码：
using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Linq;using System.Text;using System.Windows.Forms;using System.IO.Ports;using System.IO;using System.Threading;namespace COMClient{ public partial class Form1 : Form { #region 变量 /// /// 串口资源 /// private static SerialPort serialPort = null; /// /// 文件 /// private static FileStream fs = null; private static long index = 0; private static long blockCount; private static int size = 4095; private static DateTime dt; #endregion #region Form1 public Form1() { InitializeComponent(); } #endregion #region Form1_Load private void Form1_Load(object sender, EventArgs e) { serialPort = new SerialPort("COM1"); serialPort.DataReceived += new SerialDataReceivedEventHandler(serialPort_DataReceived); serialPort.Open(); } #endregion #region btnConn_Click private void btnConn_Click(object sender, EventArgs e) { if (openFileDialog1.ShowDialog() == DialogResult.OK) { dt = DateTime.Now; fs = new FileStream(openFileDialog1.FileName, FileMode.Open, FileAccess.Read); blockCount = (fs.Length - 1) / size + 1; List bList = new List (); bList.Add((int)Protocol.Client端发送文件名); bList.AddRange(ASCIIEncoding.UTF8.GetBytes(openFileDialog1.FileName)); byte[] bArr = bList.ToArray(); serialPort.Write(bArr, 0, bArr.Length); } } #endregion /// /// 接收串口数据事件 /// public void serialPort_DataReceived(object sender, SerialDataReceivedEventArgs e) { if (serialPort.BytesToRead == 0) return; int bt = serialPort.ReadByte(); switch (bt) { case (int)Protocol.Server端本次接收完毕: if (index != blockCount - 1) { byte[] bArr = new byte[size + 1]; bArr[0] = (int)Protocol.Client端发送数据块; fs.Read(bArr, 1, size); index++; Thread.Sleep(1); serialPort.Write(bArr, 0, bArr.Length); } else { byte[] bArr = new byte[fs.Length - (size * index) + 1]; bArr[0] = (int)Protocol.Client端发送最后一个数据块; fs.Read(bArr, 1, bArr.Length - 1); index++; serialPort.Write(bArr, 0, bArr.Length); } break; case (int)Protocol.Server端结束: index = 0; double totalSeconds = DateTime.Now.Subtract(dt).TotalSeconds; MessageBox.Show("完成，耗时" + totalSeconds + "秒，速度" + (fs.Length / 1024.0 / totalSeconds).ToString("#.0") + "KB/S"); fs.Close(); fs.Dispose(); break; } } }} 五、COMServer端接收文件
代码：
using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Linq;using System.Text;using System.Windows.Forms;using System.IO.Ports;using System.IO;namespace COMServer{ public partial class Form1 : Form { #region 变量 /// /// 串口资源 /// private static SerialPort serialPort = null; /// /// 文件 /// private static FileStream fs = null; #endregion #region Form1 public Form1() { InitializeComponent(); } #endregion #region Form1_Load private void Form1_Load(object sender, EventArgs e) { serialPort = new SerialPort("COM2"); serialPort.DataReceived += new SerialDataReceivedEventHandler(serialPort_DataReceived); serialPort.Open(); } #endregion /// /// 接收串口数据事件 /// public void serialPort_DataReceived(object sender, SerialDataReceivedEventArgs e) { if (serialPort.BytesToRead == 0) return; #region 接收数据 int bt = serialPort.ReadByte(); List bList = new List (); while (serialPort.BytesToRead > 0) { byte[] bArr = new byte[serialPort.BytesToRead]; serialPort.Read(bArr, 0, bArr.Length); bList.AddRange(bArr); } byte[] receiveData = bList.ToArray(); #endregion switch (bt) { case (int)Protocol.Client端发送文件名: string path = ASCIIEncoding.UTF8.GetString(receiveData); string fileName = Path.GetFileName(path); fs = new FileStream(@"d:\_临时文件\COM测试" + fileName, FileMode.Create, FileAccess.Write); byte[] bArr = new byte[1]; bArr[0] = (int)Protocol.Server端本次接收完毕; serialPort.Write(bArr, 0, bArr.Length); break; case (int)Protocol.Client端发送数据块: fs.Write(receiveData, 0, receiveData.Length); fs.Flush(); bArr = new byte[1]; bArr[0] = (int)Protocol.Server端本次接收完毕; serialPort.Write(bArr, 0, bArr.Length); break; case (int)Protocol.Client端发送最后一个数据块: fs.Write(receiveData, 0, receiveData.Length); fs.Flush(); bArr = new byte[1]; bArr[0] = (int)Protocol.Server端结束; serialPort.Write(bArr, 0, bArr.Length); fs.Close(); fs.Dispose(); break; } } }}