问题描述

我有一个类，它使用 C# 中的 DataReceived 事件处理程序从串行端口读取.当我收到数据时，我知道标头将有 5 个字节，所以我不想对数据做任何事情，直到我至少有这个.我当前的代码如下:

I have a class which reads from the serial port using the DataReceived event handler in C#. When I receive data, I know the header will have 5 bytes, so I don't want to do anything with the data until I have at least that. My current code is below:

while (serialPort.BytesToRead<5)
{
//Do nothing while we have less bytes than the header size
}

//Once at least 5 bytes are received, process header

据我了解，这段代码是阻塞的，需要改进.我正在寻找有关如何执行此操作的建议.DataReceived 事件处理程序中的另一个事件处理程序是否合适?

As I understand it, this code is blocking and needs to be improved. I'm looking for suggestions on how to do this. Would another event handler inside the DataReceived event handler be appropriate?

推荐答案

使用异步编程(不要忘记首先将您的应用程序定位到 .NET Framework 4.5).

Use async programming (don't forget to target first your application to .NET Framework 4.5).

这里你有我的实现作为 SerialPort 的扩展方法.

Here you've my implementation as extension methods for SerialPort.

using System;
using System.IO.Ports;
using System.Threading.Tasks;

namespace ExtensionMethods.SerialPort
{
    public static class SerialPortExtensions
    {
        public async static Task ReadAsync(this SerialPort serialPort, byte[] buffer, int offset, int count)
        {
            var bytesToRead = count;
            var temp = new byte[count];

            while (bytesToRead > 0)
            {
                var readBytes = await serialPort.BaseStream.ReadAsync(temp, 0, bytesToRead);
                Array.Copy(temp, 0, buffer, offset + count - bytesToRead, readBytes);
                bytesToRead -= readBytes;
            }
        }

        public async static Task<byte[]> ReadAsync(this SerialPort serialPort, int count)
        {
            var buffer = new byte[count];
            await serialPort.ReadAsync(buffer, 0, count);
            return buffer;
        }
    }
}

这里是如何阅读的:

public async void Work()
{
   try
   {
       var data = await serialPort.ReadAsync(5);
       DoStuff(data);
   }
   catch(Exception excepcion)
   {
       Trace.WriteLine(exception.Message);
   }
}

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