Erlang的gen_tcp模块packet可以指定多种参数，实现不同的数据解析方式，这里说一下line和http两种不同方式下解析的方式

-module(my_chat_server).
-export([start/1, start/0]).

start() -> start(8081).
start(Port) -> spawn_link(fun() -> start_listen(Port) end).
	
start_listen(Port) ->
       %here
	DefaultOptions = [{packet, line}, {active, false}, {reuseaddr, true}],
	case gen_tcp:listen(Port, DefaultOptions) of
		{ok, ListenSocket} ->
			par_connect(ListenSocket);
		{error, Reason} -> {error, Reason}
	end.
	
par_connect(LS) ->
	case gen_tcp:accept(LS) of
		{ok, Socket} ->
			spawn(fun() -> par_connect(LS) end),
			io:format("accept socket connection, socket=~w~n", [Socket]),
			loop(Socket);
		{error, Reason} -> {eorror, Reason}
	end.
	
loop(Socket) ->
	case gen_tcp:recv(Socket, 0) of
		{ok, Bin} ->
			%do with socket...
			io:format("deal socket data, socket=~w, data=~p~n", [Socket, Bin]),
			loop(Socket);
		{error, closed} ->
			io:format("socket closed, socket=~w~n", [Socket])
	end.

line:

2> my_chat_server:start().
<0.40.0>
accept socket connection, socket=#Port<0.1887>
deal socket data, socket=#Port<0.1887>, data="GET / HTTP/1.1\r\n"
deal socket data, socket=#Port<0.1887>, data="Host: localhost:8081\r\n"
deal socket data, socket=#Port<0.1887>, data="Connection: keep-alive\r\n"
deal socket data, socket=#Port<0.1887>, data="User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10_6_2; en-US) AppleWebKit/533.2 (KHTML, like Gecko) Chrome/5.0.342.9 Safari/533.2\r\n"
deal socket data, socket=#Port<0.1887>, data="Cache-Control: max-age=0\r\n"
deal socket data, socket=#Port<0.1887>, data="Accept: application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5\r\n"
deal socket data, socket=#Port<0.1887>, data="Accept-Encoding: gzip,deflate,sdch\r\n"
deal socket data, socket=#Port<0.1887>, data="Accept-Language: en-US,en;q=0.8\r\n"
deal socket data, socket=#Port<0.1887>, data="Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.3\r\n"
deal socket data, socket=#Port<0.1887>, data="Cookie: AJSTAT_ok_times=1; _csuid=X4b5025bb3a94d53c; view_history=47451%2Cd7dad2a908d74be19d89cbfdb355d7bc%2C62cc19edb111424a98f22dd904ccd281%2Cd5cedcf1263542c790c46a158b77e5e8%2C9de94a4094184dff97a53afe3b2cfc94%2Cdb6c1cea4986466e98b290b26d62518b\r\n"
deal socket data, socket=#Port<0.1887>, data="\r\n"

http:

1> my_chat_server:start().
<0.34.0>
accept socket connection, socket=#Port<0.440>
deal socket data, socket=#Port<0.440>, data={http_request,'GET',
                                             {abs_path,"/"},
                                             {1,1}}
deal socket data, socket=#Port<0.440>, data={http_header,14,'Host',undefined,
                                             "localhost:8081"}
deal socket data, socket=#Port<0.440>, data={http_header,2,'Connection',
                                             undefined,"keep-alive"}
deal socket data, socket=#Port<0.440>, data={http_header,24,'User-Agent',
                                             undefined,
                                             "Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10_6_2; en-US) AppleWebKit/533.2 (KHTML, like Gecko) Chrome/5.0.342.9 Safari/533.2"}
deal socket data, socket=#Port<0.440>, data={http_header,1,'Cache-Control',
                                             undefined,"max-age=0"}
deal socket data, socket=#Port<0.440>, data={http_header,8,'Accept',
                                             undefined,
                                             "application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5"}
deal socket data, socket=#Port<0.440>, data={http_header,10,
                                             'Accept-Encoding',undefined,
                                             "gzip,deflate,sdch"}
deal socket data, socket=#Port<0.440>, data={http_header,11,
                                             'Accept-Language',undefined,
                                             "en-US,en;q=0.8"}
deal socket data, socket=#Port<0.440>, data={http_header,9,'Accept-Charset',
                                             undefined,
                                             "ISO-8859-1,utf-8;q=0.7,*;q=0.3"}
deal socket data, socket=#Port<0.440>, data={http_header,50,'Cookie',
                                             undefined,
                                             "AJSTAT_ok_times=1; _csuid=X4b5025bb3a94d53c; view_history=47451%2Cd7dad2a908d74be19d89cbfdb355d7bc%2C62cc19edb111424a98f22dd904ccd281%2Cd5cedcf1263542c790c46a158b77e5e8%2C9de94a4094184dff97a53afe3b2cfc94%2Cdb6c1cea4986466e98b290b26d62518b"}
deal socket data, socket=#Port<0.440>, data=http_eoh