您好,我正在上Erlang课程,对于最终项目,我决定制作网络游戏。 我在使用用Erlang编写的服务器使用Cowboy,并且陷入了在客户端和服务器之间传输数据的过程。 我能够成功建立一个websocket连接,但是我发现很难传输json数据。
如何获取客户端发送到服务器端的信息?
客户端websocket连接建立如下:
socket = new WebSocket("ws://" + window.location.host + "/websocket");
socket.onopen = function(evt) { onOpen(evt) };
然后客户端发送json:
var data = {x_val: x,y_val: y};
socket.send(data);
带有websocket处理程序的牛仔服务器的代码
-module(ws_handler).
-export([init/2]).
-export([websocket_init/1]).
-export([websocket_handle/2]).
-export([websocket_info/2]).
init(Req, Opts) ->
{cowboy_websocket, Req, Opts}.
websocket_init(State) ->
io:fwrite("connection establish !~n", []),
erlang:start_timer(1000, self(), <<"Hello!">>),
{ok, State}.
websocket_handle({text, Msg}, State) ->
{reply, {text, << "That's what she said! ", Msg/binary >>}, State};
websocket_handle(_Data, State) ->
io:format("_Data -> Erlang\n~p\n",[_Data]),
{ok, State}.
websocket_info({timeout, _Ref, Msg}, State) ->
erlang:start_timer(1000, self(), <<"How' you doin'?">>),
{reply, {text, Msg}, State};
websocket_info(_Info, State) ->
{ok, State}.
答案 0 :(得分:2)
我找到了这个示例
https://lookonmyworks.co.uk/2014/12/21/hello-world-with-cowboy-and-websockets/
我相应地更新了ws_handler
-module(ws_handler).
-export([init/2]).
-export([websocket_init/1]).
-export([websocket_handle/2]).
-export([websocket_info/2]).
init(Req, Opts) ->
{cowboy_websocket, Req, Opts}.
websocket_init(State) ->
io:fwrite("connection establish !~n", []),
erlang:start_timer(1000, self(), <<"Hello!">>),
{ok, State}.
websocket_handle({text, Json}, State) ->
Map = jiffy:decode(Json, [return_maps]),
X_val = maps:get(<<"x_val">>, Map),
Y_val = maps:get(<<"y_val">>, Map),
Reply = #{x_val =>X_val, y_val =>Y_val},
{reply, {text, jiffy:encode(Reply)}, State}.
websocket_info({timeout, _Ref, Msg}, State) ->
erlang:start_timer(1000, self(), <<"How' you doin'?">>),
{reply, {text, Msg}, State};
websocket_info(_Info, State) ->
{ok, State}.
对于我以前使用过的客户来说,
function onMessage(ev) {
var msg = JSON.parse(ev.data);
spaceShip.v_pos.set( msg.x, msg.y);}
和客户端传输
y = y + angle_sine*0.2*sin(angle);
x = x + angle_sine*0.2*cos(angle);
var data = {x_val: x, y_val: y };
socket.send(JSON.stringify(data));