============================================HTML5 WebSocket
什么是websocket
WebSocket 协议是html5引入的一种新的协议，其目的在于实现了浏览器与服务器全双工通信。看了上面链接的同学肯定对过去怎么低效率高消耗（轮询或comet）的做此事已经有所了解了，而在websocket API，浏览器和服务器只需要要做一个握手的动作，然后，浏览器和服务器之间就形成了一条快速通道。两者之间就直接可以数据互相传送。同时这么做有两个好处
1.通信传输字节减少：比起以前使用http传输数据，websocket传输的额外信息很少，据百度说只有2k
2.服务器可以主动向客户端推送消息，而不用客户端去查询
握手
除了TCP连接的三次握手，websocket协议中客户端与服务器想建立连接需要一次额外的握手动作，在最新版的协议中是这个样子的
客户端向服务器发送请求
GET / HTTP/1.1
Upgrade: websocket
Connection: Upgrade
Host: 127.0.0.1:8080
Origin: http://test.com
Pragma: no-cache
Cache-Control: no-cache
Sec-WebSocket-Key: OtZtd55qBhJF2XLNDRgUMg==
Sec-WebSocket-Version: 13
Sec-WebSocket-Extensions: x-webkit-deflate-frame
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.57 Safari/537.36
服务器给出响应
HTTP/1.1 101 Switching Protocols
Upgrade: websocket
Connection: Upgrade
Sec-WebSocket-Accept: xsOSgr30aKL2GNZKNHKmeT1qYjA=
在请求中的“Sec-WebSocket-Key”是随机的，服务器端会用这些数据来构造出一个SHA-1的信息摘要。把“Sec-WebSocket-Key”加上一个魔幻字符串“258EAFA5-E914-47DA-95CA-C5AB0DC85B11”。使用 SHA-1 加密，之后进行 BASE-64编码，将结果做为 “Sec-WebSocket-Accept” 头的值，返回给客户端
websocket API
经过握手之后浏览器与服务器建立连接，两者就可以互相通信了。websocket的API真心很简单，看看 W3C 的定义
tring url, optional (DOMString or DOMString[]) protocols)]
interface WebSocket : EventTarget {
readonly attribute DOMString url;
// ready state
const unsigned short CONNECTING = 0;
const unsigned short OPEN = 1;
const unsigned short CLOSING = 2;
const unsigned short CLOSED = 3;
readonly attribute unsigned short readyState;
readonly attribute unsigned long bufferedAmount;
// networking
attribute EventHandler onopen;
attribute EventHandler onerror;
attribute EventHandler onclose;
readonly attribute DOMString extensions;
readonly attribute DOMString protocol;
void close([Clamp] optional unsigned short code, optional DOMString reason);
// messaging
attribute EventHandler onmessage;
attribute BinaryType binaryType;
void send(DOMString data);
void send(Blob data);
void send(ArrayBuffer data);
void send(ArrayBufferView data);
};
==================================================
创建websocket
ws=new WebSocket(address); //ws://127.0.0.1:8080
调用其构造函数，传入地址，就可以创建一个websocket了，值得注意的是地址协议得是ws/wss
关闭socket
ws.close();
调用webservice实例的close()方法就可以关闭webservice，当然也可以传入一个code和string说明为什么关了
几个回调函数句柄
由于其异步执行，回调函数自然少不了，有四个重要的
onopen：连接创建后调用
onmessage：接收到服务器消息后调用
onerror：出错时调用
onclose：关闭连接的时候调用
看名字就知道是干什么的了，每个回调函数都会传入一个Event对象，可以通过event.data访问消息
使用API
我们可以在创建socket成功后为其回调函数赋值
ws=new WebSocket(address);
ws.onopen=function(e){
var msg=document.createElement('div');
msg.style.color='#0f0';
msg.innerHTML="Server > connection open.";
msgContainer.appendChild(msg);
ws.send('{<'+document.getElementById('name').value+'>}');
};
也可以通过事件绑定的方式
ws=new WebSocket(address);
ws.addEventListener('open',function(e){
var msg=document.createElement('div');
msg.style.color='#0f0';
msg.innerHTML="Server > connection open.";
msgContainer.appendChild(msg);
ws.send('{<'+document.getElementById('name').value+'>}');
});
============================================================================
客户端实现
其实客户端的实现比较简单，除了websocket相关的几句就是一些自动focus、回车键事件处理、消息框自动定位到底部等简单功能，不一一说明了
【demo】已验证
页面
<!DOCTYPE html>
<html>
<head>
<title></title>
<script type="text/javascript">
var ws;
function ToggleConnectionClicked() {
try {
var SOCKECT_ADDR = "ws://localhost:1818/chat";
ws = new WebSocket(SOCKECT_ADDR);
ws.onopen = function (event) { alert("已经与服务器建立了连接\r\n当前连接状态：" + this.readyState); };
ws.onmessage = function (event) { alert("接收到服务器发送的数据：\r\n" + event.data); };
ws.onclose = function (event) { alert("已经与服务器断开连接\r\n当前连接状态：" + this.readyState); };
ws.onerror = function (event) {alert("WebSocket异常！" + event.toString());};
} catch (ex) {
alert(ex.message);
}
};
function SendData() {
try {
ws.send("success");
} catch (ex) {
alert(ex.message);
}
};
function seestate() {
alert(ws.readyState);
}
</script>
</head>
<body>
<button id='ToggleConnection' type="button" οnclick='ToggleConnectionClicked();'>
连接服务器</button><br />
<br />
<button id='ToggleConnection' type="button" οnclick='SendData();'>
发送我的名字：beston</button><br />
<br />
<button id='ToggleConnection' type="button" οnclick='seestate();'>
查看状态</button><br />
<br />
</body>
</html>
服务器端控制台程序
using System;
using System.Text;
using System.Net;
using System.Net.Sockets;
using System.Text.RegularExpressions;
using System.Security.Cryptography;
namespace WebSocketServer
{
class Program
{
static void Main(string[] args)
{
int port = 1818;
byte[] buffer = new byte[1024];
IPEndPoint localEP = new IPEndPoint(IPAddress.Any, port);
Socket listener = new Socket(localEP.Address.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
try
{
listener.Bind(localEP);
listener.Listen(10);
Console.WriteLine("等待客户端连接....");
Socket sc = listener.Accept();//接受一个连接
Console.WriteLine("接受到了客户端：" + sc.RemoteEndPoint.ToString() + "连接....");
//握手
int length = sc.Receive(buffer);//接受客户端握手信息
sc.Send(PackHandShakeData(GetSecKeyAccetp(buffer, length)));
Console.WriteLine("已经发送握手协议了....");
//接受客户端数据
Console.WriteLine("等待客户端数据....");
length = sc.Receive(buffer);//接受客户端信息
string clientMsg = AnalyticData(buffer, length);
Console.WriteLine("接受到客户端数据：" + clientMsg);
//发送数据
string sendMsg = "您好，" + clientMsg;
Console.WriteLine("发送数据：“" + sendMsg + "” 至客户端....");
sc.Send(PackData(sendMsg));
Console.WriteLine("演示Over!");
Console.Read();
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
/// <summary>
/// 打包握手信息
/// </summary>
/// <param name="secKeyAccept">Sec-WebSocket-Accept</param>
/// <returns>数据包</returns>
private static byte[] PackHandShakeData(string secKeyAccept)
{
var responseBuilder = new StringBuilder();
responseBuilder.Append("HTTP/1.1 101 Switching Protocols" + Environment.NewLine);
responseBuilder.Append("Upgrade: websocket" + Environment.NewLine);
responseBuilder.Append("Connection: Upgrade" + Environment.NewLine);
responseBuilder.Append("Sec-WebSocket-Accept: " + secKeyAccept + Environment.NewLine + Environment.NewLine);
//如果把上一行换成下面两行，才是thewebsocketprotocol-17协议，但居然握手不成功，目前仍没弄明白！
//responseBuilder.Append("Sec-WebSocket-Accept: " + secKeyAccept + Environment.NewLine);
//responseBuilder.Append("Sec-WebSocket-Protocol: chat" + Environment.NewLine);
return Encoding.UTF8.GetBytes(responseBuilder.ToString());
}
/// <summary>
/// 生成Sec-WebSocket-Accept
/// </summary>
/// <param name="handShakeText">客户端握手信息</param>
/// <returns>Sec-WebSocket-Accept</returns>
private static string GetSecKeyAccetp(byte[] handShakeBytes, int bytesLength)
{
string handShakeText = Encoding.UTF8.GetString(handShakeBytes, 0, bytesLength);
string key = string.Empty;
Regex r = new Regex(@"Sec\-WebSocket\-Key:(.*?)\r\n");
Match m = r.Match(handShakeText);
if (m.Groups.Count != 0)
{
key = Regex.Replace(m.Value, @"Sec\-WebSocket\-Key:(.*?)\r\n", "$1").Trim();
}
byte[] encryptionString = SHA1.Create().ComputeHash(Encoding.ASCII.GetBytes(key + "258EAFA5-E914-47DA-95CA-C5AB0DC85B11"));
return Convert.ToBase64String(encryptionString);
}
/// <summary>
/// 解析客户端数据包
/// </summary>
/// <param name="recBytes">服务器接收的数据包</param>
/// <param name="recByteLength">有效数据长度</param>
/// <returns></returns>
private static string AnalyticData(byte[] recBytes, int recByteLength)
{
if (recByteLength < 2) { return string.Empty; }
bool fin = (recBytes[0] & 0x80) == 0x80; // 1bit，1表示最后一帧
if (!fin)
{
return string.Empty;// 超过一帧暂不处理
}
bool mask_flag = (recBytes[1] & 0x80) == 0x80; // 是否包含掩码
if (!mask_flag)
{
return string.Empty;// 不包含掩码的暂不处理
}
int payload_len = recBytes[1] & 0x7F; // 数据长度
byte[] masks = new byte[4];
byte[] payload_data;
if (payload_len == 126)
{
Array.Copy(recBytes, 4, masks, 0, 4);
payload_len = (UInt16)(recBytes[2] << 8 | recBytes[3]);
payload_data = new byte[payload_len];
Array.Copy(recBytes, 8, payload_data, 0, payload_len);
}
else if (payload_len == 127)
{
Array.Copy(recBytes, 10, masks, 0, 4);
byte[] uInt64Bytes = new byte[8];
for (int i = 0; i < 8; i++)
{
uInt64Bytes[i] = recBytes[9 - i];
}
UInt64 len = BitConverter.ToUInt64(uInt64Bytes, 0);
payload_data = new byte[len];
for (UInt64 i = 0; i < len; i++)
{
payload_data[i] = recBytes[i + 14];
}
}
else
{
Array.Copy(recBytes, 2, masks, 0, 4);
payload_data = new byte[payload_len];
Array.Copy(recBytes, 6, payload_data, 0, payload_len);
}
for (var i = 0; i < payload_len; i++)
{
payload_data[i] = (byte)(payload_data[i] ^ masks[i % 4]);
}
return Encoding.UTF8.GetString(payload_data);
}
/// <summary>
/// 打包服务器数据
/// </summary>
/// <param name="message">数据</param>
/// <returns>数据包</returns>
private static byte[] PackData(string message)
{
byte[] contentBytes = null;
byte[] temp = Encoding.UTF8.GetBytes(message);
if (temp.Length < 126)
{
contentBytes = new byte[temp.Length + 2];
contentBytes[0] = 0x81;
contentBytes[1] = (byte)temp.Length;
Array.Copy(temp, 0, contentBytes, 2, temp.Length);
}
else if (temp.Length < 0xFFFF)
{
contentBytes = new byte[temp.Length + 4];
contentBytes[0] = 0x81;
contentBytes[1] = 126;
contentBytes[2] = (byte)(temp.Length & 0xFF);
contentBytes[3] = (byte)(temp.Length >> 8 & 0xFF);
Array.Copy(temp, 0, contentBytes, 4, temp.Length);
}
else
{
// 暂不处理超长内容
}
return contentBytes;
}
}
} 0
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