C# 创建“Hello World”WebSocket 示例

Creating a "Hello World" WebSocket example

提问by Tono Nam

I don't understand why I cannot make the following code work. I want to connect with JavaScript to my server console application. And then send data to the server.

我不明白为什么我不能让下面的代码工作。我想用 JavaScript 连接到我的服务器控制台应用程序。然后向服务器发送数据。

Here is the server code:

这是服务器代码：

    static void Main(string[] args)
    {            
        TcpListener server = new TcpListener(IPAddress.Parse("127.0.0.1"), 9998);
        server.Start();
        var client = server.AcceptTcpClient();
        var stream = client.GetStream();

        while (true)
        {
            var buffer = new byte[1024]; 
            // wait for data to be received
            var bytesRead = stream.Read(buffer, 0, buffer.Length);                
            var r = System.Text.Encoding.UTF8.GetString(buffer);
            // write received data to the console
            Console.WriteLine(r.Substring(0, bytesRead));
        }
    }

and here is the JavaScript:

这是 JavaScript：

        var ws = new WebSocket("ws://localhost:9998/service");
        ws.onopen = function () {
            ws.send("Hello World"); // I WANT TO SEND THIS MESSAGE TO THE SERVER!!!!!!!!
        };

        ws.onmessage = function (evt) {
            var received_msg = evt.data;
            alert("Message is received...");
        };
        ws.onclose = function () {
            // websocket is closed.
            alert("Connection is closed...");
        };

When I run that code this is what happens:

当我运行该代码时，会发生以下情况：

Note that when I run the JavaScript the server accepts and successfully establishes a connection. JavaScript is not able to send data though. Whenever I place the send method it will not send even though a connection is established. How can I make this work?

请注意，当我运行 JavaScript 时，服务器接受并成功建立连接。但是 JavaScript 无法发送数据。每当我放置发送方法时，即使建立了连接，它也不会发送。我怎样才能使这项工作？

采纳答案by moka

WebSockets is protocol that relies on TCP streamed connection. Although WebSockets is Message based protocol.

WebSockets 是依赖 TCP 流连接的协议。虽然 WebSockets 是基于消息的协议。

If you want to implement your own protocol then I recommend to use latest and stable specification (for 18/04/12) RFC 6455. This specification contains all necessary information regarding handshake and framing. As well most of description on scenarios of behaving from browser side as well as from server side. It is highly recommended to follow what recommendations tells regarding server side during implementing of your code.

如果您想实现自己的协议，那么我建议使用最新且稳定的规范（18/04/12）RFC 6455。该规范包含有关握手和帧的所有必要信息。以及大部分关于浏览器端和服务器端行为场景的描述。强烈建议在实现代码期间遵循有关服务器端的建议。

In few words, I would describe working with WebSockets like this:

简而言之，我会像这样描述使用 WebSockets 的情况：

1. Create server Socket(System.Net.Sockets) bind it to specific port, and keep listening with asynchronous accepting of connections. Something like that:

   Socket serverSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.IP);
   serverSocket.Bind(new IPEndPoint(IPAddress.Any, 8080));
   serverSocket.Listen(128);
   serverSocket.BeginAccept(null, 0, OnAccept, null);

2. You should have acceptingfunction "OnAccept" that will implement handshake. In future it has to be in another thread if system is meant to handle huge amount of connections per second.

   private void OnAccept(IAsyncResult result) {
   try {
       Socket client = null;
       if (serverSocket != null && serverSocket.IsBound) {
           client = serverSocket.EndAccept(result);
       }
       if (client != null) {
           /* Handshaking and managing ClientSocket */
       }
   } catch(SocketException exception) {
   
   } finally {
       if (serverSocket != null && serverSocket.IsBound) {
           serverSocket.BeginAccept(null, 0, OnAccept, null);
       }
   }
   }

3. After connection established, you have to do handshake. Based on specification 1.3 Opening Handshake, after connection established you will receive basic HTTP request with some information. Example:

   GET /chat HTTP/1.1
   Host: server.example.com
   Upgrade: websocket
   Connection: Upgrade
   Sec-WebSocket-Key: dGhlIHNhbXBsZSBub25jZQ==
   Origin: http://example.com
   Sec-WebSocket-Protocol: chat, superchat
   Sec-WebSocket-Version: 13

   This example is based on version of protocol 13. Bear in mind that older versions have some differences but mostly latest versions are cross-compatible. Different browsers may send you some additional data. For example Browser and OS details, cache and others.

   Based on provided handshake details, you have to generate answer lines, they are mostly same, but will contain Accpet-Key, that is based on provided Sec-WebSocket-Key. In specification 1.3 it is described clearly how to generate response key. Here is my function I've been using for V13:

   static private string guid = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
   private string AcceptKey(ref string key) {
       string longKey = key + guid;
       SHA1 sha1 = SHA1CryptoServiceProvider.Create();
       byte[] hashBytes = sha1.ComputeHash(System.Text.Encoding.ASCII.GetBytes(longKey));
       return Convert.ToBase64String(hashBytes);
   }
   

   Handshake answer looks like that:

   HTTP/1.1 101 Switching Protocols
   Upgrade: websocket
   Connection: Upgrade
   Sec-WebSocket-Accept: s3pPLMBiTxaQ9kYGzzhZRbK+xOo=

   But accept key have to be the generated one based on provided key from client and method AcceptKey I provided before. As well, make sure after last character of accept key you put two new lines "\r\n\r\n".

4. After handshake answer is sent from server, client should trigger "onopen" function, that means you can send messages after.
5. Messages are not sent in raw format, but they have Data Framing. And from client to server as well implement masking for data based on provided 4 bytes in message header. Although from server to client you don't need to apply masking over data. Read section 5. Data Framingin specification. Here is copy-paste from my own implementation. It is not ready-to-use code, and have to be modified, I am posting it just to give an idea and overall logic of read/write with WebSocket framing. Go to this link.
6. After framing is implemented, make sure that you receive data right way using sockets. For example to prevent that some messages get merged into one, because TCP is still stream based protocol. That means you have to read ONLY specific amount of bytes. Length of message is always based on header and provided data length details in header it self. So when you receiving data from Socket, first receive 2 bytes, get details from header based on Framing specification, then if mask provided another 4 bytes, and then length that might be 1, 4 or 8 bytes based on length of data. And after data it self. After you read it, apply demasking and your message data is ready to use.
7. You might want to use some Data Protocol, I recommend to use JSON due traffic economy and easy to use on client side in JavaScript. For server side you might want to check some of parsers. There is lots of them, google can be really helpful.

1. 创建服务器套接字（System.Net.Sockets）将其绑定到特定端口，并通过异步接受连接保持侦听。类似的东西：

   Socket serverSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.IP);
   serverSocket.Bind(new IPEndPoint(IPAddress.Any, 8080));
   serverSocket.Listen(128);
   serverSocket.BeginAccept(null, 0, OnAccept, null);

2. 您应该具有将实现握手的接受函数“OnAccept”。将来，如果系统要每秒处理大量连接，则它必须在另一个线程中。

   private void OnAccept(IAsyncResult result) {
   try {
       Socket client = null;
       if (serverSocket != null && serverSocket.IsBound) {
           client = serverSocket.EndAccept(result);
       }
       if (client != null) {
           /* Handshaking and managing ClientSocket */
       }
   } catch(SocketException exception) {
   
   } finally {
       if (serverSocket != null && serverSocket.IsBound) {
           serverSocket.BeginAccept(null, 0, OnAccept, null);
       }
   }
   }

3. 建立连接后，您必须进行握手。根据规范1.3 Opening Handshake，建立连接后，您将收到基本的 HTTP 请求和一些信息。例子：

   GET /chat HTTP/1.1
   Host: server.example.com
   Upgrade: websocket
   Connection: Upgrade
   Sec-WebSocket-Key: dGhlIHNhbXBsZSBub25jZQ==
   Origin: http://example.com
   Sec-WebSocket-Protocol: chat, superchat
   Sec-WebSocket-Version: 13

   此示例基于协议 13 的版本。请记住，旧版本有一些差异，但大多数最新版本是交叉兼容的。不同的浏览器可能会向您发送一些额外的数据。例如浏览器和操作系统详细信息、缓存等。

   根据提供的握手详细信息，您必须生成答案行，它们大多相同，但将包含基于提供的 Sec-WebSocket-Key 的 Accpet-Key。在规范 1.3 中清楚地描述了如何生成响应密钥。这是我用于 V13 的函数：

   static private string guid = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
   private string AcceptKey(ref string key) {
       string longKey = key + guid;
       SHA1 sha1 = SHA1CryptoServiceProvider.Create();
       byte[] hashBytes = sha1.ComputeHash(System.Text.Encoding.ASCII.GetBytes(longKey));
       return Convert.ToBase64String(hashBytes);
   }
   

   握手回答看起来像这样：

   HTTP/1.1 101 Switching Protocols
   Upgrade: websocket
   Connection: Upgrade
   Sec-WebSocket-Accept: s3pPLMBiTxaQ9kYGzzhZRbK+xOo=

   但是接受密钥必须是基于客户端提供的密钥和我之前提供的 AcceptKey 方法生成的密钥。同样，确保在接受键的最后一个字符后放置两行新行“\r\n\r\n”。

4. 从服务器发送握手应答后，客户端应触发“ onopen”功能，这意味着您可以发送消息。
5. 消息不是以原始格式发送的，但它们具有Data Framing。并且从客户端到服务器也基于消息头中提供的 4 个字节实现数据屏蔽。尽管从服务器到客户端，您不需要对数据应用屏蔽。阅读第5节。规范中的数据帧。这是我自己实现的复制粘贴。它不是现成的代码，必须进行修改，我发布它只是为了提供使用 WebSocket 框架进行读/写的想法和整体逻辑。转到此链接。
6. 实现成帧后，请确保使用套接字以正确的方式接收数据。例如为了防止某些消息合并为一个，因为 TCP 仍然是基于流的协议。这意味着您必须仅读取特定数量的字节。消息的长度始终基于标头，并在标头本身中提供数据长度详细信息。因此，当您从 Socket 接收数据时，首先接收 2 个字节，根据帧规范从标头中获取详细信息，然后如果掩码提供另外 4 个字节，然后根据数据长度可能为 1、4 或 8 个字节的长度。在数据之后它自己。阅读后，应用去掩码，您的消息数据就可以使用了。
7. 您可能想要使用一些数据协议，我建议使用 JSON 由于流量经济且易于在 JavaScript 客户端使用。对于服务器端，您可能需要检查一些解析器。有很多，谷歌真的很有帮助。

Implementing own WebSockets protocol definitely have some benefits and great experience you get as well as control over protocol it self. But you have to spend some time doing it, and make sure that implementation is highly reliable.

实现自己的 WebSockets 协议肯定有一些好处和丰富的经验，以及对协议本身的控制。但是你必须花一些时间去做，并确保实现是高度可靠的。

In same time you might have a look in ready to use solutions that google (again) have enough.

同时，您可能会查看谷歌（再次）拥有足够的现成可用的解决方案。

回答by spender

WebSockets are implemented with a protocolthat involves handshake between client and server. I don't imagine they work very much like normal sockets. Read up on the protocol, and get your application to talk it. Alternatively, use an existing WebSocket library, or .Net4.5beta which has a WebSocket API.

WebSockets 是通过一个协议实现的，该协议涉及客户端和服务器之间的握手。我不认为它们的工作方式与普通套接字非常相似。阅读协议，并让您的应用程序进行讨论。或者，使用现有的 WebSocket 库，或具有WebSocket API 的.Net4.5beta 。

回答by caesay

Issue

问题

Since you are using WebSocket, spender is correct. After recieving the initial data from the WebSocket, you need to send the handshake message from the C# server before any further information can flow.

由于您使用的是 WebSocket，因此支出者是正确的。从 WebSocket 收到初始数据后，您需要从 C# 服务器发送握手消息，然后才能传输任何进一步的信息。

HTTP/1.1 101 Web Socket Protocol Handshake
Upgrade: websocket
Connection: Upgrade
WebSocket-Origin: example
WebSocket-Location: something.here
WebSocket-Protocol: 13

Something along those lines.

沿着这些路线的东西。

You can do some more research into how WebSocket works on w3 or google.

您可以对 WebSocket 在 w3 或 google 上的工作方式进行更多研究。

Links and Resources

链接和资源

Here is a protocol specifcation: http://tools.ietf.org/html/draft-hixie-thewebsocketprotocol-76#section-1.3

这是一个协议规范：http: //tools.ietf.org/html/draft-hixie-thewebsocketprotocol-76#section-1.3

List of working examples:

工作示例列表：

• https://stackoverflow.com/a/5866975/184746
• https://stackoverflow.com/a/2212752/184746
• http://ashishware.com/websocksample.shtml
• http://www.sencha.com/forum/showthread.php?99842-WebSocket-server-in-C

• https://stackoverflow.com/a/5866975/184746
• https://stackoverflow.com/a/2212752/184746
• http://ashishware.com/websocksample.shtml
• http://www.sencha.com/forum/showthread.php?99842-WebSocket-server-in-C

回答by halfer

(Posted answer on behalf of the OP).

（代表OP发布答案）。

I am able to send data now. This is my new version of the program thanks to your answers and the code of @Maksims Mihejevs.

我现在可以发送数据了。感谢您的回答和@Maksims Mihejevs 的代码，这是我的程序的新版本。

Server

服务器

using System;
using System.Net.Sockets;
using System.Net;
using System.Security.Cryptography;
using System.Threading;

namespace ConsoleApplication1
{
    class Program
    {
        static Socket serverSocket = new Socket(AddressFamily.InterNetwork, 
        SocketType.Stream, ProtocolType.IP);
        static private string guid = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";

        static void Main(string[] args)
        {            
            serverSocket.Bind(new IPEndPoint(IPAddress.Any, 8080));
            serverSocket.Listen(128);
            serverSocket.BeginAccept(null, 0, OnAccept, null);            
            Console.Read();
        }

        private static void OnAccept(IAsyncResult result)
        {
            byte[] buffer = new byte[1024];
            try
            {
                Socket client = null;
                string headerResponse = "";
                if (serverSocket != null && serverSocket.IsBound)
                {
                    client = serverSocket.EndAccept(result);
                    var i = client.Receive(buffer);
                    headerResponse = (System.Text.Encoding.UTF8.GetString(buffer)).Substring(0,i);
                    // write received data to the console
                    Console.WriteLine(headerResponse);

                }
                if (client != null)
                {
                    /* Handshaking and managing ClientSocket */

                    var key = headerResponse.Replace("ey:", "`")
                              .Split('`')[1]                     // dGhlIHNhbXBsZSBub25jZQ== \r\n .......
                              .Replace("\r", "").Split('\n')[0]  // dGhlIHNhbXBsZSBub25jZQ==
                              .Trim();

                    // key should now equal dGhlIHNhbXBsZSBub25jZQ==
                    var test1 = AcceptKey(ref key);

                    var newLine = "\r\n";

                    var response = "HTTP/1.1 101 Switching Protocols" + newLine
                         + "Upgrade: websocket" + newLine
                         + "Connection: Upgrade" + newLine
                         + "Sec-WebSocket-Accept: " + test1 + newLine + newLine
                         //+ "Sec-WebSocket-Protocol: chat, superchat" + newLine
                         //+ "Sec-WebSocket-Version: 13" + newLine
                         ;

                    // which one should I use? none of them fires the onopen method
                    client.Send(System.Text.Encoding.UTF8.GetBytes(response));

                    var i = client.Receive(buffer); // wait for client to send a message

                    // once the message is received decode it in different formats
                    Console.WriteLine(Convert.ToBase64String(buffer).Substring(0, i));                    

                    Console.WriteLine("\n\nPress enter to send data to client");
                    Console.Read();

                    var subA = SubArray<byte>(buffer, 0, i);
                    client.Send(subA);
                    Thread.Sleep(10000);//wait for message to be send


                }
            }
            catch (SocketException exception)
            {
                throw exception;
            }
            finally
            {
                if (serverSocket != null && serverSocket.IsBound)
                {
                    serverSocket.BeginAccept(null, 0, OnAccept, null);
                }
            }
        }

        public static T[] SubArray<T>(T[] data, int index, int length)
        {
            T[] result = new T[length];
            Array.Copy(data, index, result, 0, length);
            return result;
        }

        private static string AcceptKey(ref string key)
        {
            string longKey = key + guid;
            byte[] hashBytes = ComputeHash(longKey);
            return Convert.ToBase64String(hashBytes);
        }

        static SHA1 sha1 = SHA1CryptoServiceProvider.Create();
        private static byte[] ComputeHash(string str)
        {
            return sha1.ComputeHash(System.Text.Encoding.ASCII.GetBytes(str));
        }
    }
}

JavaScript:

JavaScript：

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <script type="text/javascript">
        function connect() {
            var ws = new WebSocket("ws://localhost:8080/service");
            ws.onopen = function () {
                alert("About to send data");
                ws.send("Hello World"); // I WANT TO SEND THIS MESSAGE TO THE SERVER!!!!!!!!
                alert("Message sent!");
            };

            ws.onmessage = function (evt) {
                alert("About to receive data");
                var received_msg = evt.data;
                alert("Message received = "+received_msg);
            };
            ws.onclose = function () {
                // websocket is closed.
                alert("Connection is closed...");
            };
        };


    </script>
</head>
<body style="font-size:xx-large" >
    <div>
    <a href="#" onclick="connect()">Click here to start</a></div>
</body>
</html>

When I run that code I am able to send and receive data from both the client and the server. The only problem is that the messages are encrypted when they arrive to the server. Here are the steps of how the program runs:

当我运行该代码时，我能够从客户端和服务器发送和接收数据。唯一的问题是消息到达服务器时会被加密。以下是程序运行的步骤：

Note how the message from the client is encrypted.

注意来自客户端的消息是如何加密的。

回答by Deepak Garud

I couldnt find a simple working example anywhere (as of Jan 19), so here is an updated version. I have chrome version 71.0.3578.98.

我在任何地方都找不到一个简单的工作示例（截至 1 月 19 日），所以这里是一个更新版本。我有 chrome 版本 71.0.3578.98。

C# Websocket server :

C# Websocket 服务器：

using System;
using System.Text;
using System.Net;
using System.Net.Sockets;
using System.Security.Cryptography;

namespace WebSocketServer
{
    class Program
    {
    static Socket serverSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.IP);
    static private string guid = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";

    static void Main(string[] args)
    {
        serverSocket.Bind(new IPEndPoint(IPAddress.Any, 8080));
        serverSocket.Listen(1); //just one socket
        serverSocket.BeginAccept(null, 0, OnAccept, null);
        Console.Read();
    }

    private static void OnAccept(IAsyncResult result)
    {
        byte[] buffer = new byte[1024];
        try
        {
            Socket client = null;
            string headerResponse = "";
            if (serverSocket != null && serverSocket.IsBound)
            {
                client = serverSocket.EndAccept(result);
                var i = client.Receive(buffer);
                headerResponse = (System.Text.Encoding.UTF8.GetString(buffer)).Substring(0, i);
                // write received data to the console
                Console.WriteLine(headerResponse);
                Console.WriteLine("=====================");
            }
            if (client != null)
            {
                /* Handshaking and managing ClientSocket */
                var key = headerResponse.Replace("ey:", "`")
                          .Split('`')[1]                     // dGhlIHNhbXBsZSBub25jZQ== \r\n .......
                          .Replace("\r", "").Split('\n')[0]  // dGhlIHNhbXBsZSBub25jZQ==
                          .Trim();

                // key should now equal dGhlIHNhbXBsZSBub25jZQ==
                var test1 = AcceptKey(ref key);

                var newLine = "\r\n";

                var response = "HTTP/1.1 101 Switching Protocols" + newLine
                     + "Upgrade: websocket" + newLine
                     + "Connection: Upgrade" + newLine
                     + "Sec-WebSocket-Accept: " + test1 + newLine + newLine
                     //+ "Sec-WebSocket-Protocol: chat, superchat" + newLine
                     //+ "Sec-WebSocket-Version: 13" + newLine
                     ;

                client.Send(System.Text.Encoding.UTF8.GetBytes(response));
                var i = client.Receive(buffer); // wait for client to send a message
                string browserSent = GetDecodedData(buffer, i);
                Console.WriteLine("BrowserSent: " + browserSent);

                Console.WriteLine("=====================");
                //now send message to client
                client.Send(GetFrameFromString("This is message from server to client."));
                System.Threading.Thread.Sleep(10000);//wait for message to be sent
            }
        }
        catch (SocketException exception)
        {
            throw exception;
        }
        finally
        {
            if (serverSocket != null && serverSocket.IsBound)
            {
                serverSocket.BeginAccept(null, 0, OnAccept, null);
            }
        }
    }

    public static T[] SubArray<T>(T[] data, int index, int length)
    {
        T[] result = new T[length];
        Array.Copy(data, index, result, 0, length);
        return result;
    }

    private static string AcceptKey(ref string key)
    {
        string longKey = key + guid;
        byte[] hashBytes = ComputeHash(longKey);
        return Convert.ToBase64String(hashBytes);
    }

    static SHA1 sha1 = SHA1CryptoServiceProvider.Create();
    private static byte[] ComputeHash(string str)
    {
        return sha1.ComputeHash(System.Text.Encoding.ASCII.GetBytes(str));
    }

    //Needed to decode frame
    public static string GetDecodedData(byte[] buffer, int length)
    {
        byte b = buffer[1];
        int dataLength = 0;
        int totalLength = 0;
        int keyIndex = 0;

        if (b - 128 <= 125)
        {
            dataLength = b - 128;
            keyIndex = 2;
            totalLength = dataLength + 6;
        }

        if (b - 128 == 126)
        {
            dataLength = BitConverter.ToInt16(new byte[] { buffer[3], buffer[2] }, 0);
            keyIndex = 4;
            totalLength = dataLength + 8;
        }

        if (b - 128 == 127)
        {
            dataLength = (int)BitConverter.ToInt64(new byte[] { buffer[9], buffer[8], buffer[7], buffer[6], buffer[5], buffer[4], buffer[3], buffer[2] }, 0);
            keyIndex = 10;
            totalLength = dataLength + 14;
        }

        if (totalLength > length)
            throw new Exception("The buffer length is small than the data length");

        byte[] key = new byte[] { buffer[keyIndex], buffer[keyIndex + 1], buffer[keyIndex + 2], buffer[keyIndex + 3] };

        int dataIndex = keyIndex + 4;
        int count = 0;
        for (int i = dataIndex; i < totalLength; i++)
        {
            buffer[i] = (byte)(buffer[i] ^ key[count % 4]);
            count++;
        }

        return Encoding.ASCII.GetString(buffer, dataIndex, dataLength);
    }

    //function to create  frames to send to client 
    /// <summary>
    /// Enum for opcode types
    /// </summary>
    public enum EOpcodeType
    {
        /* Denotes a continuation code */
        Fragment = 0,

        /* Denotes a text code */
        Text = 1,

        /* Denotes a binary code */
        Binary = 2,

        /* Denotes a closed connection */
        ClosedConnection = 8,

        /* Denotes a ping*/
        Ping = 9,

        /* Denotes a pong */
        Pong = 10
    }

    /// <summary>Gets an encoded websocket frame to send to a client from a string</summary>
    /// <param name="Message">The message to encode into the frame</param>
    /// <param name="Opcode">The opcode of the frame</param>
    /// <returns>Byte array in form of a websocket frame</returns>
    public static byte[] GetFrameFromString(string Message, EOpcodeType Opcode = EOpcodeType.Text)
    {
        byte[] response;
        byte[] bytesRaw = Encoding.Default.GetBytes(Message);
        byte[] frame = new byte[10];

        int indexStartRawData = -1;
        int length = bytesRaw.Length;

        frame[0] = (byte)(128 + (int)Opcode);
        if (length <= 125)
        {
            frame[1] = (byte)length;
            indexStartRawData = 2;
        }
        else if (length >= 126 && length <= 65535)
        {
            frame[1] = (byte)126;
            frame[2] = (byte)((length >> 8) & 255);
            frame[3] = (byte)(length & 255);
            indexStartRawData = 4;
        }
        else
        {
            frame[1] = (byte)127;
            frame[2] = (byte)((length >> 56) & 255);
            frame[3] = (byte)((length >> 48) & 255);
            frame[4] = (byte)((length >> 40) & 255);
            frame[5] = (byte)((length >> 32) & 255);
            frame[6] = (byte)((length >> 24) & 255);
            frame[7] = (byte)((length >> 16) & 255);
            frame[8] = (byte)((length >> 8) & 255);
            frame[9] = (byte)(length & 255);

            indexStartRawData = 10;
        }

        response = new byte[indexStartRawData + length];

        int i, reponseIdx = 0;

        //Add the frame bytes to the reponse
        for (i = 0; i < indexStartRawData; i++)
        {
            response[reponseIdx] = frame[i];
            reponseIdx++;
        }

        //Add the data bytes to the response
        for (i = 0; i < length; i++)
        {
            response[reponseIdx] = bytesRaw[i];
            reponseIdx++;
        }

        return response;
    }
}
}

Client html and javascript:

客户端 html 和 javascript：

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <script type="text/javascript">
        var socket = new WebSocket('ws://localhost:8080/websession');
        socket.onopen = function() {
           // alert('handshake successfully established. May send data now...');
     socket.send("Hi there from browser.");
        };
  socket.onmessage = function (evt) {
                //alert("About to receive data");
                var received_msg = evt.data;
                alert("Message received = "+received_msg);
            };
        socket.onclose = function() {
            alert('connection closed');
        };
    </script>
</head>
<body>
</body>
</html>