public sealed partial class MainPage : Page
{
// DatagramSocket 支持使用 UDP 数据报套接的网络通信
DatagramSocket udpSocket = null;
//定义本地端口号
const string LOCAL_PORT = “12200″;
public MainPage()
{
this.InitializeComponent();
this.NavigationCacheMode = NavigationCacheMode.Required;
}

bool isUdpSocketInitializzed = false; //表示是否初始化过
//若要接收 DatagramSocket 对象上的数据，应用程序必须将 MessageReceived 事件分配给事件
//处理程序，然后调用 BindEndpointAsync 或 BindServiceNameAsync 方法将 DatagramSocket
//绑定到本地服务名或 UDP 端口上。ConnectAsync 方法还会导致绑定操作。
//写入由一个 GetOutputStreamAsync 方法返回的流也将会导致绑定操作。
//然后 DatagramSocket 可以接收数据报。
protected async override void OnNavigatedTo(NavigationEventArgs e)
{
if (!isUdpSocketInitializzed)
{
udpSocket = new DatagramSocket();
//定义在DatagramSocket对象上接受消息的事件
udpSocket.MessageReceived += udpSocket_MessageReceived;
//启动DatagramSocket本地服务名的绑定操作
await udpSocket.BindServiceNameAsync(LOCAL_PORT);
// 标志初始已完成
isUdpSocketInitializzed = true;
}
}

async void udpSocket_MessageReceived(DatagramSocket sender, DatagramSocketMessageReceivedEventArgs args)
{
//获取DatagramSocket，以获取从DatagramSocket对象上的的远程网络目标接受到的传入数据
var reader = args.GetDataReader();
// 数据长度
uint len = reader.UnconsumedBufferLength;
// 读取内容
string message = reader.ReadString(len);
// 获取主机的IP地址和端口号
string host = string.Format(“{0}:{1}”, args.RemoteAddress.DisplayName, args.RemotePort);
await Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
{
lbMessages.Items.Add(“来自” + host + “的消息：\n” + message);
});
}

private async void btnSend_Click(object sender, RoutedEventArgs e)
{
if (string.IsNullOrWhiteSpace(txtToSend.Text) || string.IsNullOrWhiteSpace(txtRemoteIP.Text) || string.IsNullOrWhiteSpace(txtRemotePort.Text))
{
return;
}
// 获取输出流的引用
HostName remoteHost = new HostName(txtRemoteIP.Text);
IOutputStream outStream = await udpSocket.GetOutputStreamAsync(remoteHost, txtRemotePort.Text);
// 发送消息
DataWriter writer = new DataWriter(outStream);
//设置字符编码
writer.UnicodeEncoding = UnicodeEncoding.Utf8;
//将字符串值写入输出流
writer.WriteString(txtToSend.Text);
// 提交数据
await writer.StoreAsync();
//释放
writer.DetachStream();
writer.Dispose();
tbMessage.Text = “已发送。”;
txtToSend.Text = “”;
}

public partial class MainWindow : Window
{
UdpClient udpClnt = null;
const int LOCAL_PORT = 9899;//本地端口
CancellationTokenSource cancelSrc = null;
public MainWindow()
{
InitializeComponent();
this.Closing += (a, b) =>
{
if (udpClnt != null)
{
try
{
udpClnt.Close();
}
catch (SocketException sex)
{
System.Diagnostics.Debug.WriteLine(sex.Message);
}
}
};
}
private async void DoReceiveMsg()
{
while (!cancelSrc.IsCancellationRequested)
{
try
{
var result = await udpClnt.ReceiveAsync();
// 远程主面信息
string host = string.Format(“{0}:{1}”, result.RemoteEndPoint.Address.ToString(), result.RemoteEndPoint.Port);
// 读取消息
string msg = Encoding.UTF8.GetString(result.Buffer);
// 显示接到的信息
await Dispatcher.BeginInvoke(new Action(
() =>
{
this.lbMessages.Items.Add(“来自” + host + “的消息：\n” + msg);
}
));
}
catch
{
continue;
}
}
}

private void btnEnableRecv_Click(object sender, RoutedEventArgs e)
{
CheckUdpClient();

// 开始异步接收消息
cancelSrc = new CancellationTokenSource();
Task runTask = new Task(new Action(DoReceiveMsg), cancelSrc.Token);
try
{
runTask.Start();//启动后台任务
tbMessage.Text = “后台接收已开启。”;
btnEnableRecv.IsEnabled = false;
btnDisableRecv.IsEnabled = true;
}
catch (TaskCanceledException)
{
tbMessage.Text = “后台接收任务已取消。”;
}
catch (Exception ex)
{
System.Diagnostics.Debug.WriteLine(ex.Message);
}
}

/// <summary>
/// 检测UdpClient对象是否已创建
/// </summary>
private void CheckUdpClient()
{
if (udpClnt == null) udpClnt = new UdpClient(LOCAL_PORT);
}

private void btnDisableRecv_Click(object sender, RoutedEventArgs e)
{
// 取消后台任务
if (cancelSrc != null)
{
cancelSrc.Cancel();
btnEnableRecv.IsEnabled = true;
btnDisableRecv.IsEnabled = false;
tbMessage.Text = “已取消后台接收消息。”;
}
}

private async void btnSend_Click(object sender, RoutedEventArgs e)
{
if (string.IsNullOrWhiteSpace(txtToSend.Text))
{
return;
}
CheckUdpClient();
// 验证是否设置远程地址和端口
IPAddress ip;
int remotePort;
if (!IPAddress.TryParse(txtRemoteIP.Text,out ip))
{
MessageBox.Show(“请输入远程IP地址。”); return;
}
if (!int.TryParse(txtRemotePort.Text, out remotePort))
{
MessageBox.Show(“请输入远程端口号。”); return;
}
// 验证输入的端口号是否合法
if (remotePort < IPEndPoint.MinPort || remotePort > IPEndPoint.MaxPort)
{
MessageBox.Show(string.Format(“端口号的有效范围在{0}到{1}。”, IPEndPoint.MinPort, IPEndPoint.MaxPort));
return;
}
// 开始发送消息
byte[] buffer = Encoding.UTF8.GetBytes(txtToSend.Text);
// 创建远程终结点
IPEndPoint remote = new IPEndPoint(ip, remotePort);
object contentTemp = btnSend.Content;
try
{
btnSend.Content = “正在发送”;
btnSend.IsEnabled = false;
await udpClnt.SendAsync(buffer, buffer.Length, remote);
txtToSend.Clear();
tbMessage.Text = “已发送。”;
}
catch (Exception ex)
{
tbMessage.Text = “消息发送失败。”;
System.Diagnostics.Debug.WriteLine(ex.Message);
}
finally
{
// 发送完毕
btnSend.Content = contentTemp;
btnSend.IsEnabled = true;
}
}