当我尝试从客户端发送消息时，服务器无法接收并打印该消息。谁能告诉我以下服务器客户端应用程序中的错误。
我创建了两个 WinForm 项目，一个是 UDP 服务器，另一个是 UDP 客户端。
在 UDP 服务器项目中，我创建了一个表单，其中包含一个名为richTextBox1 的 RichTextBox 来显示消息和一个名为 btStart 的按钮来启动/停止监听。这是代码片段：
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.Net;
using System.Net.Sockets;
using System.Threading;
namespace UDPServer
{
public partial class Form1 : Form
{
delegate void ShowMessageMethod(string msg);
UdpClient _server = null;
IPEndPoint _client = null;
Thread _listenThread = null;
private bool _isServerStarted = false;
public Form1()
{
InitializeComponent();
}
private void serverMsgBox_Load(object sender, EventArgs e)
{
this.btStart.Text = "StartServer";
}
private void Form1_Load(object sender, EventArgs e)
{
}
private void btStart_Click(object sender, EventArgs e)
{
if (_isServerStarted)
{
Stop();
btStart.Text = "StartServer";
}
else
{
Start();
btStart.Text = "StopServer";
}
}
private void Start()
{
//Create the server.
IPEndPoint serverEnd = new IPEndPoint(IPAddress.Any, 1234);
_server = new UdpClient(serverEnd);
ShowMsg("Waiting for a client...");
//Create the client end.
_client = new IPEndPoint(IPAddress.Any, 0);
//Start listening.
Thread listenThread = new Thread(new ThreadStart(Listening));
listenThread.Start();
//Change state to indicate the server starts.
_isServerStarted = true;
}
private void Stop()
{
try
{
//Stop listening.
listenThread.Join();
ShowMsg("Server stops.");
_server.Close();
//Changet state to indicate the server stops.
_isServerStarted = false;
}
catch (Exception excp)
{ }
}
private void Listening()
{
byte[] data;
//Listening loop.
while (true)
{
//receieve a message form a client.
data = _server.Receive(ref _client);
string receivedMsg = Encoding.ASCII.GetString(data, 0, data.Length);
//Show the message.
this.Invoke(new ShowMessageMethod(ShowMsg), new object[] { "Client:" + receivedMsg });
//Send a response message.
data = Encoding.ASCII.GetBytes("Server:" + receivedMsg);
_server.Send(data, data.Length, _client);
//Sleep for UI to work.
Thread.Sleep(500);
}
}
private void ShowMsg(string msg)
{
this.richTextBox1.Text += msg + "\r\n";
}
}
}
在 UDP 客户端项目中，我还创建了一个表单，其中包含一个名为 RichTextBox1 的 RichTextBox 用于输入或显示消息，一个名为 btSend 的按钮用于发送输入消息。您可以运行该项目的多个实例。服务器将处理所有正在运行的客户端。这是代码片段：
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.Net.Sockets;
using System.Net;
using System.Threading;
namespace UDPClient
{
public partial class Form1 : Form
{
UdpClient _server = null;
IPEndPoint _client = null;
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
}
private void serverMsgBox_Load(object sender, EventArgs e)
{
//Get the server.
_server = new UdpClient("127.0.0.1", 16000);
//Create a client.
_client = new IPEndPoint(IPAddress.Any, 0);
}
private void Form1_FormClosing(object sender, FormClosingEventArgs e)
{
try
{
_server.Close();
}
catch (Exception s)
{
}
}
private void btSend_Click(object sender, EventArgs e)
{
try
{
//Send the input message.
string text = this.richTextBox1.Text;
_server.Send(Encoding.ASCII.GetBytes(text), text.Length);
//Receive the response message.
byte[] data = _server.Receive(ref _client);
string msg = Encoding.ASCII.GetString(data, 0, data.Length);
//Show the response message.
this.richTextBox1.Text = msg;
}
catch (Exception exp)
{
}
}
}
}