Hololens的应用需要与其他设备通信的时候，UDP是比较方便的一种方式，Unity3d 2017.3 C#开发的时候可以用Windows.Networking.Sockets.DatagramSocket 类来接收、发送UDP消息，简单快捷。

.net 的System.net.Socket对象应该也可以，但是只支持部分方法，一开始没走通所以我没继续测试下去。

开发的时候注意两个地方：

1、DatagramSocket.MessageReceived 事件不在主线程运行，所以在这个事件中不能操作UI的东西，比如给文本框赋值，否则报错。

2、Unity Build的时候Player Settings要勾选 PrivateNetworkClientServer，注意跟InternetClientServer不一样。因为我是在局域网测试，一开始只是勾选了InternetClientServer，结果无法接收消息。

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下面是网上找的一个UDP收发消息的类：

using UnityEngine;

using System;

using System.IO;

using System.Text;

using System.Linq;

using HoloToolkit.Unity;

using System.Collections.Generic;

using UnityEngine.Events;

#if !UNITY_EDITOR

using Windows.Networking.Sockets;

using Windows.Networking.Connectivity;

using Windows.Networking;

#endif

[System.Serializable]

public class UDPMessageEvent : UnityEvent

{

}

public class UDPCommunication : Singleton

{

[Tooltip("port to listen for incoming data")]

public string internalPort = "12345";

[Tooltip("IP-Address for sending")]

public string externalIP = "192.168.17.110";

[Tooltip("Port for sending")]

public string externalPort = "12346";

[Tooltip("Send a message at Startup")]

public bool sendPingAtStart = true;

[Tooltip("Conten of Ping")]

public string PingMessage = "hello";

[Tooltip("Function to invoke at incoming packet")]

public UDPMessageEvent udpEvent = null;

private readonly Queue ExecuteOnMainThread = new Queue();

#if !UNITY_EDITOR

//we've got a message (data[]) from (host) in case of not assigned an event

void UDPMessageReceived(string host, string port, byte[] data)

{

Debug.Log("GOT MESSAGE FROM: " + host + " on port " + port + " " + data.Length.ToString() + " bytes ");

}

//Send an UDP-Packet

public async void SendUDPMessage(string HostIP, string HostPort, byte[] data)

{

await _SendUDPMessage(HostIP, HostPort, data);

}

DatagramSocket socket;

async void Start()

{

if (udpEvent == null)

{

udpEvent = new UDPMessageEvent();

udpEvent.AddListener(UDPMessageReceived);

}

Debug.Log("Waiting for a connection...");

/**

*关键点一：创建使用UDP的网络通信对象:DatagramSocket，然后添加接收消息的事件MessageReceived

*/

socket = new DatagramSocket();

socket.MessageReceived += Socket_MessageReceived;

HostName IP = null;

try

{

var icp = NetworkInformation.GetInternetConnectionProfile();

IP = Windows.Networking.Connectivity.NetworkInformation.GetHostNames()

.SingleOrDefault(

hn =>

hn.IPInformation?.NetworkAdapter != null && hn.IPInformation.NetworkAdapter.NetworkAdapterId

== icp.NetworkAdapter.NetworkAdapterId);

/**

* 关键点二：绑定IP和监听端口，IP如果传null好像不行。

*/

await socket.BindEndpointAsync(IP, internalPort);

}

catch (Exception e)

{

Debug.Log(e.ToString());

Debug.Log(SocketError.GetStatus(e.HResult).ToString());

return;

}

if (sendPingAtStart)

SendUDPMessage(externalIP, externalPort, Encoding.UTF8.GetBytes(PingMessage));

}

private async System.Threading.Tasks.Task _SendUDPMessage(string externalIP, string externalPort, byte[] data)

{

using (var stream = await socket.GetOutputStreamAsync(new Windows.Networking.HostName(externalIP), externalPort))

{

using (var writer = new Windows.Storage.Streams.DataWriter(stream))

{

writer.WriteBytes(data);

await writer.StoreAsync();

}

}

}

#else

// to make Unity-Editor happy :-)

void Start()

{

}

public void SendUDPMessage(string HostIP, string HostPort, byte[] data)

{

}

#endif

static MemoryStream ToMemoryStream(Stream input)

{

try

{ // Read and write in

byte[] block = new byte[0x1000]; // blocks of 4K.

MemoryStream ms = new MemoryStream();

while (true)

{

int bytesRead = input.Read(block, 0, block.Length);

if (bytesRead == 0) return ms;

ms.Write(block, 0, bytesRead);

}

}

finally { }

}

// Update is called once per frame

void Update()

{

/**

* 关键点四：由主线程触发事件，避免外面调用的类可能出错。

*/

while (ExecuteOnMainThread.Count > 0)

{

ExecuteOnMainThread.Dequeue().Invoke();

}

}

#if !UNITY_EDITOR

private void Socket_MessageReceived(Windows.Networking.Sockets.DatagramSocket sender,

Windows.Networking.Sockets.DatagramSocketMessageReceivedEventArgs args)

{

Debug.Log("GOT MESSAGE FROM: " + args.RemoteAddress.DisplayName);

//Read the message that was received from the UDP client.

Stream streamIn = args.GetDataStream().AsStreamForRead();

MemoryStream ms = ToMemoryStream(streamIn);

byte[] msgData = ms.ToArray();

/**

* 关键点三：接收到数据用事件发送出去，这里只是把触发事件的代码放到队列ExecuteOnMainThread中。

* 是因为接收函数是多线程的，跟Unity主线程不一样，自己开发的时候如果在这里给文本框赋值会报错！

*/

if (ExecuteOnMainThread.Count == 0)

{

ExecuteOnMainThread.Enqueue(() =>

{

Debug.Log("ENQEUED ");

if (udpEvent != null)

udpEvent.Invoke(args.RemoteAddress.DisplayName, internalPort, msgData);

});

}

}

#endif

}

然后是Player Settings截图：