我正在尝试实现包装器类,它只需连接到TCP服务器并等待数据.一旦从服务器提交数据 – 我将收到这些数据并将其传递给我班级的订阅者.
这一切都有效.现在我想添加外部功能,以便在计时器上“重置”此类(强制每次重新连接)以保持连接活动.我的想法是可以根据需要多次调用Init方法来重置套接字.但是,我确实得到了各种例外.
班级代码：
namespace Ditat.GateControl.Service.InputListener
{
using System;
using System.ComponentModel;
using System.Net;
using System.Net.sockets;
using System.Text;
public class BaseTcpsocketListener : IInputListener
{
#region Events/Properties
public event EventHandler<Exception> OnError;
public event EventHandler<string> OnDataReceived;
private string host;
private int port;
private int delayToClearBufferSeconds = 5;
private TcpClient client;
private readonly byte[] buffer = new byte[1024];
/// <summary>
/// Will accumulate data as it's received
/// </summary>
private string DataBuffer { get; set; }
/// <summary>
/// Store time of last data receipt. Need this in order to purge data after delay
/// </summary>
private DateTime LastDataReceivedOn { get; set; }
#endregion
public BaseTcpsocketListener()
{
// Preset all entries
this.LastDataReceivedOn = DateTime.UtcNow;
this.DataBuffer = string.Empty;
}
public void Init(string config)
{
// Parse info
var bits = config.Split(new[] { '|' },StringSplitOptions.RemoveEmptyEntries);
this.host = bits[0];
var hostBytes = this.host.Split(new[] { '.' },StringSplitOptions.RemoveEmptyEntries);
var hostIp = new IPAddress(new[] { byte.Parse(hostBytes[0]),byte.Parse(hostBytes[1]),byte.Parse(hostBytes[2]),byte.Parse(hostBytes[3]) });
this.port = int.Parse(bits[1]);
this.delayToClearBufferSeconds = int.Parse(bits[2]);
// Close open client
if (this.client?.Client != null)
{
this.client.Client.disconnect(true);
this.client = null;
}
// Connect to client
this.client = new TcpClient();
if (!this.client.ConnectAsync(hostIp,this.port).Wait(2500))
throw new Exception($"Failed to connect to {this.host}:{this.port} in allotted time");
this.EstablishReceiver();
}
protected void DataReceived(IAsyncResult result)
{
// End the data receiving that the socket has done and get the number of bytes read.
var bytesCount = 0;
try
{
bytesCount = this.client.Client.EndReceive(result);
}
catch (Exception ex)
{
this.RaiSEOnErrorToClient(new Exception(nameof(this.DataReceived)));
this.RaiSEOnErrorToClient(ex);
}
// No data received,establish receiver and return
if (bytesCount == 0)
{
this.EstablishReceiver();
return;
}
// Convert the data we have to a string.
this.DataBuffer += Encoding.UTF8.GetString(this.buffer,bytesCount);
// Record last time data received
this.LastDataReceivedOn = DateTime.UtcNow;
this.RaiSEOnDataReceivedToClient(this.DataBuffer);
this.DataBuffer = string.Empty;
this.EstablishReceiver();
}
private void EstablishReceiver()
{
try
{
// Set up again to get the next chunk of data.
this.client.Client.BeginReceive(this.buffer,this.buffer.Length,SocketFlags.None,this.DataReceived,this.buffer);
}
catch (Exception ex)
{
this.RaiSEOnErrorToClient(new Exception(nameof(this.EstablishReceiver)));
this.RaiSEOnErrorToClient(ex);
}
}
private void RaiSEOnErrorToClient(Exception ex)
{
if (this.OnError == null) return;
foreach (Delegate d in this.OnError.GetInvocationList())
{
var syncer = d.Target as isynchronizeInvoke;
if (syncer == null)
{
d.DynamicInvoke(this,ex);
}
else
{
syncer.BeginInvoke(d,new object[] { this,ex });
}
}
}
private void RaiSEOnDataReceivedToClient(string data)
{
if (this.OnDataReceived == null) return;
foreach (Delegate d in this.OnDataReceived.GetInvocationList())
{
var syncer = d.Target as isynchronizeInvoke;
if (syncer == null)
{
d.DynamicInvoke(this,data);
}
else
{
syncer.BeginInvoke(d,data });
}
}
}
}
}
客户端代码(在按钮上单击表单)
private void ListenBaseButton_Click(object sender,EventArgs e)
{
if (this.bsl == null)
{
this.bsl = new BaseTcpsocketListener();
this.bsl.OnDataReceived += delegate (object o,string s)
{
this.DataTextBox.Text += $"Base: {DateTime.Now} - {s}" + Environment.NewLine;
};
this.bsl.OnError += delegate (object o,Exception x)
{
this.DataTextBox.Text += $"Base TCP receiver error: {DateTime.Now} - {x.Message}" + Environment.NewLine;
};
}
try
{
this.bsl.Init("192.168.33.70|10001|10");
this.DataTextBox.Text += "BEGIN RECEIVING BSL data --------------------------" + Environment.NewLine;
}
catch (Exception exception)
{
this.DataTextBox.Text += $"ERROR CONNECTING TO BSL ------------{exception.Message}" + Environment.NewLine;
}
}
我得到的例外情况.在DataReceived中从处理程序第二次单击按钮时的第一个异常
The IAsyncResult object was not returned from the corresponding
asynchronous method on this class.
在跟随点击后,我从EstablishReceiver中的处理程序获得异常
A request to send or receive data was disallowed because the socket is
not connected and (when sending on a datagram socket using a sendto
call) no address was supplied
如何正确确保插座关闭并重新打开？
解决方法
The IAsyncResult object was not returned from the corresponding
asynchronous method on this class.
这是在为先前的套接字调用数据回调(DataReceived())时发生的众所周知的问题.在这种情况下,您将使用不正确的IAsyncResult实例调用Socket.EndReceive(),该实例将抛出异常.
Asynchronous Client Socket Example包含此问题的可能解决方法：在状态对象中调用BeginReceive()的存储套接字,然后传递给DataReceived回调：
StateObject类
public class StateObject
{
public Socket Socket { get; set; }
public byte[] Buffer { get; } = new byte[1024];
public StateObject(Socket socket)
{
Socket = socket;
}
}
EstablishReceiver()方法：
private void EstablishReceiver()
{
try
{
var state = new StateObject(client.Client);
// Set up again to get the next chunk of data.
this.client.Client.BeginReceive(state.Buffer,state.Buffer.Length,state);
}
catch (Exception ex)
{
this.RaiSEOnErrorToClient(new Exception(nameof(this.EstablishReceiver)));
this.RaiSEOnErrorToClient(ex);
}
}
DataReceived()方法：
protected void DataReceived(IAsyncResult result)
{
var state = (StateObject) result.AsyncState;
// End the data receiving that the socket has done and get the number of bytes read.
var bytesCount = 0;
try
{
SocketError errorCode;
bytesCount = state.socket.EndReceive(result,out errorCode);
if (errorCode != SocketError.Success)
{
bytesCount = 0;
}
}
catch (Exception ex)
{
this.RaiSEOnErrorToClient(new Exception(nameof(this.DataReceived)));
this.RaiSEOnErrorToClient(ex);
}
if (bytesCount > 0)
{
// Convert the data we have to a string.
this.DataBuffer += Encoding.UTF8.GetString(state.Buffer,bytesCount);
// Record last time data received
this.LastDataReceivedOn = DateTime.UtcNow;
this.RaiSEOnDataReceivedToClient(this.DataBuffer);
this.DataBuffer = string.Empty;
this.EstablishReceiver();
}
}
A request to send or receive data was disallowed because the socket is
not connected and (when sending on a datagram socket using a sendto
call) no address was supplied
上面的DataReceived()方法还包含第二个异常的修复程序.在断开连接的套接字上调用BeginReceive()(来自EstablishReceiver())会导致异常.如果先前的读取带来0字节,则不应在套接字上调用BeginReceive().
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