路由¶

基本结构:

Routes = [Host]
Host = {HostMatch, PathsList} | {HostMatch, Constraints, PathsList}.
PathsList = [Path].
Path = {PathMatch, Handler, Opts} | {PathMatch, Constraints, Handler, Opts}.
PathMatch: string() or binary()

Match详解:

PathMatch1 = "/".
PathMatch2 = "/path/to/resource".
HostMatch1 = "cowboy.example.org".

% 下面两句一样
PathMatch2 = "/path/to/resource".
PathMatch3 = "/path/to/resource/".

% 下面三句一样
HostMatch1 = "cowboy.example.org".
HostMatch2 = "cowboy.example.org.".
HostMatch3 = ".cowboy.example.org".

% binding
PathMatch = "/hats/:name/prices".
HostMatch = ":subdomain.example.org".
% http://test.example.org/hats/gordon/prices
erl> cowboy_req:binding/{2,3}
name => gordon
subdomain => test

% :_的用法
% 后面不取它的值,类似erlang的_
HostMatch = "ninenines.:_".
PathMatch = "/hats/:name/:name".


% []指定可选
PathMatch = "/hats/[page/:number]".
HostMatch = "[www.]ninenines.eu".
PathMatch = "/hats/[page/[:number]]".

% [...]:多匹配
PathMatch = "/hats/[...]".
HostMatch = "[...]ninenines.eu".
erl> cowboy_req:host_info/1和cowboy_req:path_info/1

% '_':匹配任意host或path
% "*":通配符匹配,通常与OPTION方法一起使用
PathMatch = '_'.
HostMatch = '_'.

HostMatch = "*".

编译:

% cowboy_route:compile/2
Dispatch = cowboy_router:compile([
    %% {HostMatch, list({PathMatch, Handler, Opts})}
    {'_', [{'_', my_handler, []}]}
]),
%% Name, NbAcceptors, TransOpts, ProtoOpts
cowboy:start_http(my_http_listener, 100,
    [{port, 8080}],
    [{env, [{dispatch, Dispatch}]}]
).

在线更新:

% cowboy:set_env/3:
Dispatch = cowboy_router:compile(Routes),
cowboy:set_env(my_http_listener, dispatch, Dispatch).

router:

% 1.在应用的priv_dir/static/目录下,所有文件的路由
% 2.文件priv/index.html
Dispatch = [
    {'_', [
        {"/[...]", cowboy_static, [
            {directory, {priv_dir, my_app, [<<"static">>]}},
            {file, "index.html"},
            {mimetypes, {fun mimetypes:path_to_mimes/2, default}}
        ]}
    ]}
].