即时通讯框架T-io之WebSocket协议再之HelloWorld-白红宇

一.t-io是干嘛的

这个框架已经开源到码云上面，介绍比较详细，链接：，由于官方介绍中的入门程序客户端和服务端都是用的java写的，而且是用简单的自定义TCP协议进行通信的，也有一个websocket协议的列子，感觉有点复杂，不好入门。就想着使用javascript来做客户端，t-io做服务端，采用websocket协议搞一个helloworld。

二.WebSocket协议咋回事

首先，t-io框架简单说就是封装一下些个：

内置心跳检测

内置心跳发送

各种便捷的绑定API

各种便捷的发送API

一行代码拥有自动重连功能

各项消息统计等功能，全部一键内置搞定，省却各种烦恼

所以我们收到客户端发来的websocket协议的包，在服务端就要做对应的解包，那我们还要了解websocket包的结构和通信建立的过程：

①握手阶段：

客户端和服务器建立TCP连接之后，客户端发送握手请求，随后服务器发送握手响应即完成握手阶段。如下：

客户端握手请求类似如下：

GET /chat HTTP/1.1Host: server.example.comUpgrade: websocketConnection: UpgradeSec-WebSocket-Key: x3JJHMbDL1EzLkh9GBhXDw==Sec-WebSocket-Protocol: chat, superchatSec-WebSocket-Version: 13Origin: http://example.com复制代码

服务器的握手响应类似如下：

HTTP/1.1 101 Switching ProtocolsUpgrade: websocketConnection: UpgradeSec-WebSocket-Accept: HSmrc0sMlYUkAGmm5OPpG2HaGWk=Sec-WebSocket-Protocol: chat复制代码

②握手成功后开始发送数据帧

这是Websocket的数据传输协议，聊天信息一般会按照这个协议的规则来传输，下图中的一整个东西称为一个数据帧，数据帧的成帧和解析是处理这个协议时最麻烦的一部分了。具体这个表怎么看可以参照

0                   1                   2                   3  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-------+-+-------------+-------------------------------+ |F|R|R|R| opcode|M| Payload len |    Extended payload length    | |I|S|S|S|  (4)  |A|     (7)     |             (16/64)           | |N|V|V|V|       |S|             |   (if payload len==126/127)   | | |1|2|3|       |K|             |                               | +-+-+-+-+-------+-+-------------+ - - - - - - - - - - - - - - - + |     Extended payload length continued, if payload len == 127  | + - - - - - - - - - - - - - - - +-------------------------------+ |                               |Masking-key, if MASK set to 1  | +-------------------------------+-------------------------------+ | Masking-key (continued)       |          Payload Data         | +-------------------------------- - - - - - - - - - - - - - - - + :                     Payload Data continued ...                : + - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - + |                     Payload Data continued ...                | +---------------------------------------------------------------+ 具体每一bit的意思FIN      1bit 表示信息的最后一帧RSV 1-3  1bit each 以后备用的 默认都为 0Opcode   4bit 帧类型，稍后细说Mask     1bit 掩码，是否加密数据，默认必须置为1 （这里很蛋疼）Payload  7bit 数据的长度Masking-key      1 or 4 bit 掩码Payload data     (x + y) bytes 数据Extension data   x bytes  扩展数据Application data y bytes  程序数据复制代码

三.T-io服务端编写

整体的编写和框架自带的Helloworld程序模式一致，需要改变的就是encode()编码方法和decode()解码方法，因为需要根据websocket协议来。

收到消息后先解码，再判断包的类型，交给响应类型的handler。发送消息先编码。

①握手

decode()解码方法：

由于客户端收到的第一个包是握手包，所以：

if (!barrageSessionContext.isHandshaked()) // 如果还没有握手，则先进行握手操作{    if (BarragePacket.HANDSHAKE_BYTE == firstbyte) {        buffer.position(1 + initPosition);        return handshakePacket;    } else {        HttpRequestPacket httpRequestPacket = HttpRequestDecoder.decode(buffer);        if (httpRequestPacket == null) {            return null;        }        //交给握手包的Handler        httpRequestPacket.setType(Type.COMMAND_HANDSHAKE_REQ);        barrageSessionContext.setWebsocket(true);        return httpRequestPacket;    }}//握手成功后在barrageSessionContext中保存此次连接的握手情况.boolean isWebsocket = barrageSessionContext.isWebsocket();复制代码

握手包的Handler，返回握手响应包，让客户端知道握手成功，可以进行数据传输了，：

public class HandshakeReqHandler implements BarrageHandlerIntf
    
      {    private BarragePacket handshakeRespPacket = new BarragePacket(Type.COMMAND_HANDSHAKE_RESP);    @Override    public Object handler(            BarragePacket packet,            String body,            ChannelContext
     
       channelContext)            throws Exception {        BarrageSessionContext barrageSessionContext = channelContext.getSessionContext();        barrageSessionContext.setHandshaked(true);        boolean isWebsocket = barrageSessionContext.isWebsocket();        if (isWebsocket)        {            HttpRequestPacket httpRequestPacket = (HttpRequestPacket) packet;            HttpResponsePacket httpResponsePacket = updateWebSocketProtocol(httpRequestPacket);            if (httpResponsePacket != null)            {                //发送握手响应包，交给握手响应的handler                httpResponsePacket.setType(Type.COMMAND_HANDSHAKE_RESP);                Aio.send(channelContext, httpResponsePacket);            } else            {                Aio.remove(channelContext, "不是websocket协议");            }        } else        {            Aio.send(channelContext, handshakeRespPacket);        }        return null;    }    public HttpResponsePacket updateWebSocketProtocol(HttpRequestPacket httpRequestPacket)    {        Map
      
        headers = httpRequestPacket.getHeaders();        String Sec_WebSocket_Key = headers.get("Sec-WebSocket-Key");        if (StringUtils.isNotBlank(Sec_WebSocket_Key))        {            String Sec_WebSocket_Key_Magic = Sec_WebSocket_Key + "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";            byte[] key_array = SHA1Util.SHA1(Sec_WebSocket_Key_Magic);            String acceptKey = BASE64Util.byteArrayToBase64(key_array);            HttpResponsePacket httpResponsePacket = new HttpResponsePacket();            HttpResponseStatus httpResponseStatus = HttpResponseStatus.C101;            httpResponsePacket.setHttpResponseStatus(httpResponseStatus);            Map
       
         respHeaders = new HashMap<>();            respHeaders.put("Connection", "Upgrade");            respHeaders.put("Upgrade", "WebSocket");            respHeaders.put("Sec-WebSocket-Accept", acceptKey);            httpResponsePacket.setHeaders(respHeaders);            return httpResponsePacket;        }        return null;    }}复制代码

encode()编码方法:

上面在握手包的handler中，调用了send方法，发送了一个握手响应包，所以要在编码的时候先判断是否是握手响应包，对其编码：

if (packet.getType() == Type.COMMAND_HANDSHAKE_RESP) {    if (isWebsocket) {        return HttpResponseEncoder.encode((HttpResponsePacket) packet, groupContext, channelContext);    } else {        ByteBuffer buffer = ByteBuffer.allocate(1);        buffer.put(BarragePacket.HANDSHAKE_BYTE);        return buffer;    }}复制代码

握手响应包的编码

public static ByteBuffer encode(HttpResponsePacket httpResponsePacket, GroupContext
    
      groupContext, ChannelContext
     
       channelContext)    {        int bodyLength = 0;        byte[] httpResponseBody = httpResponsePacket.getHttpResponseBody();        if (httpResponseBody != null)        {            bodyLength = httpResponseBody.length;        }        StringBuilder sb = new StringBuilder(128);        HttpResponseStatus httpResponseStatus = httpResponsePacket.getHttpResponseStatus();        //        httpResponseStatus.get        sb.append("HTTP/1.1 ").append(httpResponseStatus.getStatus()).append(" ").append(httpResponseStatus.getDescription()).append("\r\n");        Map
      
        headers = httpResponsePacket.getHeaders();        if (headers != null && headers.size() > 0)        {            headers.put("Content-Length", bodyLength + "");            Set
       
        
         > set = headers.entrySet();            for (Entry
         
           entry : set) { sb.append(entry.getKey()).append(": ").append(entry.getValue()).append("\r\n"); } } sb.append("\r\n"); byte[] headerBytes = null; try { headerBytes = sb.toString().getBytes("utf-8"); } catch (Exception e) { throw new RuntimeException(e); } ByteBuffer buffer = ByteBuffer.allocate(headerBytes.length + bodyLength); buffer.put(headerBytes); if (bodyLength > 0) { buffer.put(httpResponseBody); } return buffer; }复制代码

②数据包

decode()解码方法：

上面握手成功的时候会在BarrageSessionContext中保存握手的情况。

if (isWebsocket) // 走的websocket协议{    WebsocketPacket websocketPacket = WebsocketDecoder.decode(buffer, channelContext);    if (websocketPacket == null) {        return null;    }    Opcode opcode = websocketPacket.getWsOpcode();    if (opcode == Opcode.BINARY) {        byte[] wsBody = websocketPacket.getWsBody();        if (wsBody == null || wsBody.length == 0) {            throw new AioDecodeException("错误的websocket包，body为空");        }        BarragePacket barragePacket = new BarragePacket(Type.COMMAND_HANDSHAKE_RESP);        if (wsBody.length > 1) {            byte[] dst = new byte[wsBody.length - 1];            System.arraycopy(wsBody, 1, dst, 0, dst.length);            barragePacket.setBody(dst);        }        return barragePacket;    } else if (opcode == Opcode.PING || opcode == Opcode.PONG) {        return heartbeatPacket;    } else if (opcode == Opcode.CLOSE) {        BarragePacket barragePacket = new BarragePacket(Type.COMMAND_CLOSE_REQ);        return barragePacket;    } else if (opcode == Opcode.TEXT) {        byte[] wsBody = websocketPacket.getWsBody();        if (wsBody == null || wsBody.length == 0) {            throw new AioDecodeException("错误的websocket包，body为空");        }        BarragePacket barragePacket = new BarragePacket(Type.P2P_REQ);        if (wsBody.length > 1) {            barragePacket.setBody(wsBody);        }        return barragePacket;    } else {        throw new AioDecodeException("错误的websocket包，错误的Opcode");    }} else {    if (BarragePacket.HEARTBEAT_BYTE == firstbyte) {        buffer.position(1 + initPosition);        return heartbeatPacket;    }}复制代码

数据包的handler：

public class P2PReqHandler implements BarrageHandlerIntf
    
     {    @Override    public Object handler(            BarragePacket packet,            String jsonStr,            ChannelContext
     
       channelContext)            throws Exception {        System.out.println(jsonStr);        BarragePacket barragePacket = new BarragePacket(Type.P2P_REQ);        barragePacket.setBody(("收到了你的消息，你的消息是:" + jsonStr).getBytes(BarragePacket.CHARSET));        Aio.send(channelContext, barragePacket);        return null;    }}复制代码

这个收到消息后的处理是，发送收到的消息到客户端。

encode()编码方法:

如果不是握手响应包，走websocket包的编码if (isWebsocket) {    return WebsocketEncoder.encode(packet, groupContext, channelContext);}复制代码

public static ByteBuffer encode(BarragePacket barragePacket, GroupContext
    
      groupContext,            ChannelContext
     
       channelContext){    byte[] websocketHeader;    byte[] imBody = barragePacket.getBody();    int wsBodyLength = 1; //固定有一个命令码，占一位    if (imBody != null)    {        wsBodyLength += imBody.length;    }    byte header0 = (byte) (0x8f & (Opcode.BINARY.getCode() | 0xf0));    if (wsBodyLength < 126)    {        websocketHeader = new byte[2];        websocketHeader[0] = header0;        websocketHeader[1] = (byte) wsBodyLength;    } else if (wsBodyLength < ((1 << 16) - 1))    {        websocketHeader = new byte[4];        websocketHeader[0] = header0;        websocketHeader[1] = 126;        websocketHeader[3] = (byte) (wsBodyLength & 0xff);        websocketHeader[2] = (byte) ((wsBodyLength >> 8) & 0x80);    } else    {        websocketHeader = new byte[6];        websocketHeader[0] = header0;        websocketHeader[1] = 127;        int2Byte(websocketHeader, wsBodyLength, 2);    }    ByteBuffer buf = ByteBuffer.allocate(websocketHeader.length + wsBodyLength);    buf.put(websocketHeader);    buf.put(barragePacket.getType());    if (imBody != null)    {        buf.put(imBody);    }    return buf;}public static void int2Byte(byte[] bytes, int value, int offset){    checkLength(bytes, 4, offset);    bytes[offset + 3] = (byte) ((value & 0xff));    bytes[offset + 2] = (byte) ((value >> 8 * 1) & 0xff);    bytes[offset + 1] = (byte) ((value >> 8 * 2) & 0xff);    bytes[offset + 0] = (byte) ((value >> 8 * 3));}private static void checkLength(byte[] bytes, int length, int offset){    if (bytes == null)    {        throw new IllegalArgumentException("null");    }    if (offset < 0)    {        throw new IllegalArgumentException("invalidate offset " + offset);    }    if (bytes.length - offset < length)    {        throw new IllegalArgumentException("invalidate length " + bytes.length);    }}复制代码

websocket协议的服务器的处理流程大致是上面这个流程，但是代码我只贴了关键部分，完整的代码可以去我的码云上下载。

四.javascript客户端编写

Testing websockets
      
        
       
    
  
    
  复制代码

最好是下载程序下来，打上断点，debug去跟一下，每一步包做了那些处理，变成了什么样子，传输的二进制数据转换成字符串是甚么样子等等。

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