Erlang与Flash的Socket通信－02
前一次实验，我使用的是本地swf文件，所以没有遇到安全沙箱问题，但在实际环境中我们的Flash文件是通过URL引用的，这时候Flash的Socket通讯会受到安全沙箱机制的限制。具体原理是：Flash在尝试向服务器A发起Socket连接前，会先尝试连接服务器A的843端口，求情一个xml格式的安全策略文件，该文件告诉Flash是否有权限向服务器A发起Socket连接。所以，我们需要在Erlang端增设一个守候在843端口的安全策略文件服务器。
此次实验的Erlang代码：
-module(server).
-export([start/1]).
-export([policy_file_server/0, policy_file_server_proc/1]).
-export([flash_socket_server/1, flash_socket_server_proc/1]).
start (Port) ->
spawn(?MODULE, policy_file_server, []),
spawn(?MODULE, flash_socket_server, [Port]).
%%------------------------------------------
%% Flash Policy File Server
%%------------------------------------------
policy_file_server () ->
{ok, LSock} = gen_tcp:listen(843, [binary, {packet, 0}, {active, false}]),
policy_file_server_accept(LSock).
policy_file_server_accept (LSock) ->
case gen_tcp:accept(LSock) of
{ok, Sock} ->
spawn(?MODULE, policy_file_server_proc, [Sock]),
policy_file_server_accept(LSock);
{error, Reason} ->
io:format("policy file server exit: ~s~n", [Reason]),
exit(Reason)
end.
policy_file_server_proc (Sock) ->
case gen_tcp:recv(Sock, 0) of
{ok, _} ->
gen_tcp:send(Sock, <<
"<?xml version=\"1.0\"?>"
"<cross-domain-policy>",
"<allow-access-from domain=\"*\" to-ports=\"*\" />",
"</cross-domain-policy>",0
>>);
_ ->
ok
end,
gen_tcp:close(Sock).
%%------------------------------------------
%% Flash Socket Server
%%------------------------------------------
flash_socket_server (Port) ->
{ok, LSock} = gen_tcp:listen(Port, [list, {packet, 2}, {active, false}]),
flash_socket_server_accpet(LSock).
flash_socket_server_accpet (LSock) ->
case gen_tcp:accept(LSock) of
{ok, Sock} ->
spawn(?MODULE, flash_socket_server_proc, [Sock]),
flash_socket_server_accpet(LSock);
{error, Reason} ->
io:format("flash socket server exit: ~s~n", [Reason]),
exit(Reason)
end.
flash_socket_server_proc (Sock) ->
case gen_tcp:recv(Sock, 0) of
{ok, Request} ->
io:format("Received: ~p~n", [Request]),
gen_tcp:send(Sock, "done!"),
flash_socket_server_proc(Sock);
{error, closed} ->
io:format("Client closed~n"),
exit(closed);
{error, Reason} ->
io:format("Error: ~s~n", Reason),
exit(Reason)
end.
在调试Flash端时，我调试了很久都没有效果，最后发现原来是浏览器缓存问题。
以下是Flash端的实验代码：
package
{
import flash.events.MouseEvent;
import flash.events.ProgressEvent;
import flash.net.Socket;
import flash.display.Sprite;
import flash.text.TextField;
import flash.text.TextFieldAutoSize;
public class Main extends Sprite
{
private var sock:Socket;
private var send:TextField;
private var input:TextField;
private var output:TextField;
public function Main ()
{
send = new TextField();
send.border = true;
send.multiline = true;
send.autoSize = TextFieldAutoSize.CENTER;
send.htmlText = "<a href='event:#'> Send </a>";
send.mouseEnabled = true;
send.selectable = false;
send.x = 320 - send.width;
send.y = 20;
send.height = 21;
input = new TextField();
input.border = true;
input.type = "input";
input.autoSize = TextFieldAutoSize.NONE;
input.x = 20;
input.y = 20;
input.width = 300 - send.width - 10;
input.height = 19;
output = new TextField();
output.border = true;
output.multiline = true;
output.autoSize = TextFieldAutoSize.NONE;
output.x = 20;
output.y = 20 + input.height + 10;
output.width = 300;
output.height = 300;
output.wordWrap = true;
addChild(send);
addChild(input);
addChild(output);
sock = new Socket();
sock.addEventListener(
ProgressEvent.SOCKET_DATA,
function (event:ProgressEvent):void
{
/* 与Erlang端{packet, 0}对应的代码
while (sock.bytesAvailable)
{
var s:String = sock.readUTFBytes(sock.bytesAvailable);
output.appendText(s);
}
*/
/* 与Erlang端{packet, 0}对应的代码 */
var s:String = sock.readUTF();
input.text = "";
output.appendText(s);
output.appendText("\r\n");
}
);
sock.connect("localhost", 10086);
sock.flush();
send.addEventListener(
MouseEvent.CLICK,
function (event:MouseEvent):void
{
/* 与Erlang端{packet, 0}对应的代码
sock.writeUTFBytes("Hello World!");
*/
/* 与Erlang端{packet, 0}对应的代码 */
sock.writeUTF(input.text);
sock.flush();
}
);
}
}
}