Erlang通过WebSocket和浏览器交互

来源：互联网发布：提升视频画质软件编辑：程序博客网时间：2024/06/05 01:02

本文是用Erlang通过WebSocket协议实现的一个简单的服务器端的double计算器，Erlang下面有成熟的Web框架Cowboy，但本着了解原理的心态没有用这个框架，代码如下：

<!DOCTYPE html><html> <head>  <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />  <title>Erlang & WebSocket</title>  <script type="text/javascript">    function doubleNum() {        var o = document.getElementById("number");        var socket = new WebSocket("ws://127.0.0.1:8181");        socket.onopen = function() {            socket.send(o.value);            socket.onmessage = function(r) {                o.value = r.data;                socket.close();                socket=null;            }        }    }  </script> </head> <body>  <input type="text" size=10 value=100 id="number">  <input type="button" value="Double" onclick="doubleNum()"> </body></html>

-module(clock_demo).-export([start/0]).start() ->    case gen_tcp:listen(8181, [binary,{packet,0},{active,true},{reuseaddr,true},{packet_size,1024*2},{keepalive,true}]) of        {ok,Listen} ->            spawn(fun()->par_connect(Listen) end);        _Err ->            io:format("Accept failed:~w~n", [_Err])    end.par_connect(Listen) ->    {ok,Socket} = gen_tcp:accept(Listen),    spawn(fun()->par_connect(Listen) end),    wait(Socket).wait(Socket) ->    receive        {tcp,Socket,Bin} ->            gen_tcp:send(Socket, list_to_binary(handshake(Bin))),            loop(Socket);        Any ->            io:format("Received(2): ~p~n",[Any]),            wait(Socket)    end.loop(Socket) ->    receive        {tcp,Socket,Data} ->            %% 打印Brorser发送上来的数据            io:format("Received(3): ~s~n",[websocket_data(Data)]),            %% 向Brorser发送数据            gen_tcp:send(Socket, [build_client_data( integer_to_binary(binary_to_integer(websocket_data(Data))*2 ))]),            loop(Socket);        Any ->            io:format("Received(4): ~p~n", [Any]),            loop(Socket)    end.handshake(Bin) ->    Key = list_to_binary(lists:last(string:tokens(hd(lists:filter(fun(S) -> lists:prefix("Sec-WebSocket-Key:", S) end, string:tokens(binary_to_list(Bin), "\r\n"))), ": "))),    Accept = base64:encode(crypto:hash(sha,<< Key/binary, "258EAFA5-E914-47DA-95CA-C5AB0DC85B11" >>)),    %%{ok, Write_log} = file:open("D:/Erlang/erlang_log",[append]),    %%io:format(Write_log, "Accept: ~s~n", [Accept]),    [     "HTTP/1.1 101 Switching Protocols\r\n",    "connection: Upgrade\r\n",    "upgrade: websocket\r\n",    "Blog: http://blog.csdn.net/jom_ch\r\n",    "sec-websocket-accept: ", Accept, "\r\n",    "\r\n"    ].%% 仅处理长度为125以内的文本消息websocket_data(Data) when is_list(Data) ->    websocket_data(list_to_binary(Data));websocket_data(<< 1:1, 0:3, 1:4, 1:1, Len:7, MaskKey:32, Rest/bits >>) when Len < 126 ->    <<End:Len/binary, _/bits>> = Rest,    Text = websocket_unmask(End, MaskKey, <<>>),    Text;websocket_data(_) ->    <<>>. %% 由于Browser发过来的数据都是mask的,所以需要unmaskwebsocket_unmask(<<>>, _, Unmasked) ->    Unmasked;websocket_unmask(<< O:32, Rest/bits >>, MaskKey, Acc) ->    T = O bxor MaskKey,    websocket_unmask(Rest, MaskKey, << Acc/binary, T:32 >>);websocket_unmask(<< O:24 >>, MaskKey, Acc) ->    << MaskKey2:24, _:8 >> = << MaskKey:32 >>,    T = O bxor MaskKey2,    << Acc/binary, T:24 >>;websocket_unmask(<< O:16 >>, MaskKey, Acc) ->    << MaskKey2:16, _:16 >> = << MaskKey:32 >>,    T = O bxor MaskKey2,    << Acc/binary, T:16 >>;websocket_unmask(<< O:8 >>, MaskKey, Acc) ->    << MaskKey2:8, _:24 >> = << MaskKey:32 >>,    T = O bxor MaskKey2,    << Acc/binary, T:8 >>.%% 发送文本给Clientbuild_client_data(Data) ->    Len = iolist_size(Data),    BinLen = payload_length_to_binary(Len),    [<< 1:1, 0:3, 1:4, 0:1, BinLen/bits >>, Data].payload_length_to_binary(N) ->    case N of        N when N =< 125 -> << N:7 >>;        N when N =< 16#ffff -> << 126:7, N:16 >>;        N when N =< 16#7fffffffffffffff -> << 127:7, N:64 >>    end.

参考：http://www.cnblogs.com/suex/p/3669953.html

0 0