Erlang的socket 编程简例

来源：互联网发布：钱龙软件编辑：程序博客网时间：2024/06/03 22:59

Erlang 中gen_tcp 用于编写TCP程序，gen_udp用于编写UDP程序。一个简单的TCP服务器echo示例：

Start_echo_server()->

{ok,Listen}= gen_tcp:listen(1234,[binary,{packet,4},{reuseaddr,true},{active,true}]),

{ok,socket}=get_tcp:accept(Listen),

gen_tcp:close(Listen),

loop(Socket).

loop(Socket) ->

receive

{tcp,Socket,Bin} ->

io:format(“serverreceived binary = ~p~n”,[Bin])

Str= binary_to_term(Bin),

io:format(“server (unpacked) ~p~n”,[Str]),

Reply= lib_misc:string2value(Str),

io:format(“serverreplying = ~p~n”,[Reply]),

gen_tcp:send(Socket,term_to_binary(Reply)),

loop(Socket);

{tcp_closed,Socket} ->

Io:format(“ServerSocket closed ~n”)

end.

Tcp 的echo客户端示例：

echo_client_eval(Str) ->

{Ok,Socket} = gen_tcp:connect(“localhost”,2345,[binary,{packet,4}]),

ok= gen_tcp:send(Socket, term_to_binary(Str)),

receive

{tcp,Socket,Bin}->

Io:format(“Clientreceived binary = ~p~n”,[Bin]),

Val=binary_to_term(Bin),

io:format(“Clientresult = ~p~n”,[Val]),

gen_tcp:close(Socket)

end.

UDP server示例

udp_demo_server(Port) ->

{ok,Socket}= gen_udp:open(Open,[Binary]),

loop(Socket).

Loop(Socket)->

receive

{udp,Socket,Host,Port,Bin}->

BinReply= …,

gen_udp:send(Socket,Host,Port,BinReply),

loop(Socket)

End.

UDP client 示例：

udp_demo_client(Request) ->

{ok,Socket}= gen_udp:open(0,[Binary]),

ok= gen_udp:send(Socket,”localhost”,1234,Request),

Value= receive

{udp,Socket,_,_,Bin}-> {ok,Bin}

after2000 -> error

end,

gen_udp:close(Socket),

Value

注意，因为UDP是不可靠的，一定要设一个超时时间，而且Reqeust最好小于500字节。

WebSocket， JS 和Erlang相结合，能够实现Web的绝大多数功能。

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