专题七：UDP编程补充——UDP广播程序的实现

一、程序实现

UDP广播程序的实现代码：

  1 using System;
  2 using System.Net;
  3 using System.Net.Sockets;
  4 using System.Text;
  5 using System.Threading;
  6 using System.Windows.Forms;
  7 
  8 namespace UDPBroadcast
  9 {
 10     /// <summary>
 11     /// 在界面上，用户可以设置本地进程的IP地址和端口号，并将地址加入某个组播组；
 12     /// 可以输入发送消息的目的组的地址，并且勾选“广播”复选框将采用广播的方式发送信息
 13     /// 在界面上点击“接受按钮”就启动接收线程，这样程序就可以接收广播或组播的信息
 14     /// </summary>
 15     public partial class UdpBroadcasefrm : Form
 16     {
 17         private UdpClient sendUdpClient;
 18         private UdpClient receiveUdpClient;
 19         // 组播IP地址
 20         IPEndPoint broadcastIpEndPoint;
 21         public UdpBroadcasefrm()
 22         {
 23             InitializeComponent();
 24             IPAddress[] ips = Dns.GetHostAddresses(Dns.GetHostName());
 25             tbxlocalip.Text = ips[5].ToString();
 26             tbxlocalport.Text = "8002";
 27             // 默认组,组播地址是有范围
 28             // 具体关于组播和广播的介绍参照我上一篇博客UDP编程
 29             // 本地组播组
 30             tbxGroupIp.Text = "224.0.0.1";
 31             // 发送到的组播组
 32             tbxSendToGroupIp.Text = "224.0.0.1";
 33         }
 34 
 35         // 设置加入组
 36         private void chkbxJoinGtoup_Click(object sender, EventArgs e)
 37         {
 38             if (chkbxJoinGtoup.Checked == true)
 39             {
 40                 tbxGroupIp.Enabled = false;
 41             }
 42             else
 43             {
 44                 tbxGroupIp.Enabled = true;
 45                 tbxGroupIp.Focus();
 46             }
 47         }
 48 
 49         // 选择发送模式后设置
 50         private void chkbxBroadcast_Click(object sender, EventArgs e)
 51         {
 52             if (chkbxBroadcast.Checked == true)
 53             {
 54                 tbxSendToGroupIp.Enabled = false;
 55             }
 56             else
 57             {
 58                 tbxSendToGroupIp.Enabled = true;
 59                 tbxSendToGroupIp.Focus();
 60             }
 61         }
 62 
 63         // 发送消息
 64         private void btnSend_Click(object sender, EventArgs e)
 65         {
 66             if (tbxMessageSend.Text == "")
 67             {
 68                 MessageBox.Show("消息内容不能为空！","提示");
 69                 return;
 70             }
 71 
 72             // 根据选择的模式发送信息
 73             if (chkbxBroadcast.Checked == true)
 74             {
 75                 // 广播模式(自动获得子网中的IP广播地址)
 76                 broadcastIpEndPoint = new IPEndPoint(IPAddress.Broadcast, 8002);
 77             }
 78             else
 79             {
 80                 // 组播模式
 81                 broadcastIpEndPoint = new IPEndPoint(IPAddress.Parse(tbxSendToGroupIp.Text), 8002);
 82             }
 83 
 84             // 启动发送线程发送消息
 85             Thread sendThread = new Thread(SendMessage);
 86             sendThread.Start(tbxMessageSend.Text);
 87         }
 88 
 89         // 发送消息
 90         private void SendMessage(object obj)
 91         {
 92             string message = obj.ToString();
 93             byte[] messagebytes = Encoding.Unicode.GetBytes(message);
 94             sendUdpClient = new UdpClient();
 95             // 发送消息到组播或广播地址
 96             sendUdpClient.Send(messagebytes, messagebytes.Length, broadcastIpEndPoint);
 97             sendUdpClient.Close();
 98             
 99             // 清空编辑消息框
100             ResetMessageText(tbxMessageSend);
101         }
102 
103         // 利用委托回调机制来实现界面上的消息清空操作
104         delegate void ResetMessageTextCallBack(TextBox textbox);
105         private void ResetMessageText(TextBox textbox)
106         {
107             if (textbox.InvokeRequired)
108             {
109                 ResetMessageTextCallBack resetMessageCallback = ResetMessageText;
110                 textbox.Invoke(resetMessageCallback, new object[] { textbox });
111             }
112             else
113             {
114                 textbox.Clear();
115                 textbox.Focus();
116             }
117         }
118 
119         // 接收消息
120         private void btnReceive_Click(object sender, EventArgs e)
121         {
122             chkbxJoinGtoup.Enabled = false;
123             // 创建接收套接字
124             IPAddress localIp = IPAddress.Parse(tbxlocalip.Text);
125             IPEndPoint localIpEndPoint = new IPEndPoint(localIp, int.Parse(tbxlocalport.Text));
126             receiveUdpClient = new UdpClient(localIpEndPoint);
127             // 加入组播组
128             if (chkbxJoinGtoup.Checked == true)
129             {
130                 receiveUdpClient.JoinMulticastGroup(IPAddress.Parse(tbxGroupIp.Text));
131                 receiveUdpClient.Ttl = 50;
132             }
133 
134             // 启动接受线程
135             Thread threadReceive = new Thread(ReceiveMessage);
136             threadReceive.Start();
137         }
138 
139         // 接受消息方法
140         private void ReceiveMessage()
141         {
142             IPEndPoint remoteIpEndPoint = new IPEndPoint(IPAddress.Any, 0);
143             while (true)
144             {
145                 try
146                 {
147                     // 关闭receiveUdpClient时此时会产生异常
148                     byte[] receiveBytes = receiveUdpClient.Receive(ref remoteIpEndPoint);
149                     string receivemessage = Encoding.Unicode.GetString(receiveBytes);
150 
151                     // 显示消息内容
152                     ShowMessage(lstMessageBox, string.Format("{0}[{1}]", remoteIpEndPoint, receivemessage));
153                 }
154                 catch
155                 {
156                     break;
157                 }
158             }
159         }
160         // 通过委托回调机制显示消息内容
161         delegate void ShowMessageCallBack(ListBox listbox,string text);
162         private void ShowMessage(ListBox listbox, string text)
163         {
164             if (listbox.InvokeRequired)
165             {
166                 ShowMessageCallBack showmessageCallback = ShowMessage;
167                 listbox.Invoke(showmessageCallback, new object[] { listbox, text });
168             }
169             else
170             {
171                 listbox.Items.Add(text);
172                 listbox.SelectedIndex = listbox.Items.Count - 1;
173                 listbox.ClearSelected();
174             }
175         }
176 
177         // 清空消息列表
178         private void btnClear_Click(object sender, EventArgs e)
179         {
180             lstMessageBox.Items.Clear();
181         }
182 
183         // 停止接收
184         private void btnStop_Click(object sender, EventArgs e)
185         {
186             chkbxJoinGtoup.Enabled =true;
187             receiveUdpClient.Close();
188         }
189 
190        
191     }
192 }