using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Net;
using System.Threading;
using System.Net.Sockets;


namespace UDP广播2
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            Control.CheckForIllegalCrossThreadCalls = false;//允许交差线程访问(没这个就不能在别的进程修改textBox了)
        }

        EndPoint ep;
        string receiveData;
        Socket socket;

        private void Acc()
        {
            socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
            IPEndPoint iep = new IPEndPoint(IPAddress.Any, 8899);
            socket.Bind(iep);
            ep = (EndPoint)iep;
            byte[] bytes = new byte[1024];
            byte[] initbytes = new byte[1024];
            while (true)
            {
                try
                {
                    initbytes.CopyTo(bytes,0);
                    socket.ReceiveFrom(bytes, ref ep);
                    receiveData = System.Text.Encoding.Unicode.GetString(bytes);
                    receiveData = receiveData.TrimEnd('\u0000');
                    if (receiveData.Length > 0)
                    {
                        richTextBox1.Text = "来自" + ep.ToString() + "的消息" + receiveData;
                    }
                }
                catch
                {
                    break;
                }
            }
        }

        private void Form1_FormClosing(object sender, FormClosingEventArgs e)
        {
            socket.Close();
        }

        Socket socket2 = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);//只能用UDP协议发送广播，所以ProtocolType设置为UDP
        IPEndPoint iep = new IPEndPoint(IPAddress.Broadcast, 8899);                                //让其自动提供子网中的IP地址
        byte[] bytes;

        private void button2_Click(object sender, EventArgs e)
        {
            
            bytes = Encoding.Unicode.GetBytes(textBox1.Text);                    //将发送内容转换为字节数组
            textBox1.Text = "";
            socket2.SendTo(bytes, iep);
        }

        private void button1_Click(object sender, EventArgs e)
        {

            socket2.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.Broadcast, 1);           //设置broadcast值为1，允许套接字发送广播信息
            button1.Enabled = false;
            Thread th = new Thread(new ThreadStart(Acc));
            th.Start();
        }

    }
}