quick-cocos2d-x 学习系列之十二 关于websocket

quick-cocos2d-x 学习系列之十二 关于websocket

1.概念

百度百科：WebSocket protocol 是HTML5一种新的协议。它实现了浏览器与服务器全双工通信(full-duplex)。

在浏览器中通过http仅能实现单向的通信,comet可以一定程度上模拟双向通信,但效率较低,并需要服务器有较好的支持; flash中的socket和xmlsocket可以实现真正的双向通信,通过 flex ajax bridge,可以在javascript中使用这两项功能. 可以预见,如果websocket一旦在浏览器中得到实现,将会替代上面两项技术,得到广泛的使用.面对这种状况，HTML5定义了WebSocket协议，能更好的节省服务器资源和带宽并达到实时通讯。

在JavaEE7中也实现了WebSocket协议。

实现了websocket的浏览器：

Chrome	Supported in version 4+
Firefox	Supported in version 4+
Internet Explorer	Supported in version 10+
Opera	Supported in version 10+
Safari	Supported in version 5+

所以这个websocket还是比较靠谱的协议。那么在LUA中如何使用呢？

我们还是以DEMO为引子。

2.Websocket类

创建一个websocket类如下：

local WebSockets = class("WebSockets")

WebSockets.TEXT_MESSAGE = 0

WebSockets.BINARY_MESSAGE = 1

WebSockets.BINARY_ARRAY_MESSAGE = 2

WebSockets.OPEN_EVENT = "open"

WebSockets.MESSAGE_EVENT = "message"

WebSockets.CLOSE_EVENT = "close"

WebSockets.ERROR_EVENT = "error"

function WebSockets:ctor(url)

cc(self):addComponent("components.behavior.EventProtocol"):exportMethods()

self.socket = cc.WebSocket:create(url)

if self.socket then

self.socket:registerScriptHandler(handler(self,self.onopen_),cc.WEBSOCKET_OPEN)

self.socket:registerScriptHandler(handler(self,self.onMessage_),cc.WEBSOCKET_MESSAGE)

self.socket:registerScriptHandler(handler(self,self.onClose_),cc.WEBSOCKET_CLOSE)

self.socket:registerScriptHandler(handler(self,self.onError_),cc.WEBSOCKET_ERROR)

end

end

function WebSockets:isReady()

return self.socket and self.socket:getReadyState() == cc.WEBSOCKET_STATE_OPEN

end

function WebSockets:send(data, messageType)

if not self:isReady() then

printError("WebSockets:send() - socket is't ready")

return false

end

messageType = checkint(messageType)

self.messageType = messageType

if messageType == WebSockets.TEXT_MESSAGE then

self.socket:sendString(tostring(data))

elseif messageType == WebSockets.BINARY_ARRAY_MESSAGE then

data = checktable(data)

self.socket:sendString(data,table.nums(data))

else

self.socket:sendString(tostring(data))

end

return true

end

function WebSockets:close()

if self.socket then

self.socket:close()

self.socket = nil

end

self:removeAllEventListeners()

end

function WebSockets:onopen_()

self:dispatchEvent({name = WebSockets.OPEN_EVENT})

end

function WebSockets:onMessage_(message)

local params = {

name = WebSockets.MESSAGE_EVENT,

message = message,

messageType = self.messageType

}

self:dispatchEvent(params)

end

function WebSockets:onClose_()

self:dispatchEvent({name = WebSockets.CLOSE_EVENT})

self:close()

end

function WebSockets:onError_(error)

self:dispatchEvent({name = WebSockets.ERROR_EVENT,error = error})

end

return WebSockets

3.MainScene

调用该类的场景MainScene,如下。

local WebSockets = require("WebSockets")

local MainScene = class("MainScene",function()

return display.newScene("MainScene")

end)

local function bin2hex(binary)

local t = {}

for i = 1,string.len(binary) do

t[#t + 1] = string.format("0x%02x",string.byte(binary, i))

end

return table.concat(t," ")

end

function MainScene:ctor()

local connectLabel =

cc.ui.UIPushButton.new()

:setButtonLabel(cc.ui.UILabel.new({text= "connect",size = 32}))

:onButtonClicked(function()

self:onConnectClicked()

end)

:align(display.CENTER,display.cx,display.top - 32)

:addTo(self)

local sendTextLabel =

cc.ui.UIPushButton.new()

:setButtonLabel(cc.ui.UILabel.new({text= "send text",size = 32}))

:onButtonClicked(function()

self:onSendTextClicked()

end)

:align(display.CENTER,display.top - 64)

:addTo(self)

local sendBinaryLabel =

cc.ui.UIPushButton.new()

:setButtonLabel(cc.ui.UILabel.new({text= "send binary",size = 32}))

:onButtonClicked(function()

self:onSendBinaryClicked()

end)

:align(display.CENTER,display.top - 96)

:addTo(self)

end

function MainScene:onopen(event)

print("connected")

end

function MainScene:onMessage(event)

if WebSockets.BINARY_MESSAGE == event.messageType then

printf("receive binary msg: len = %s,binary = %s",string.len(event.message), bin2hex(event.message))

else

printf("receive text msg: %s",event.message)

end

end

function MainScene:onClose(event)

self.websocket = nil

end

function MainScene:onError(event)

printf("error %s",event.error)

self.websocket = nil

end

function MainScene:onConnectClicked()

if self.websocket then return end

self.websocket = WebSockets.new("ws://echo.websocket.org")

self.websocket:addEventListener(WebSockets.OPEN_EVENT,handler(self, self.onopen))

self.websocket:addEventListener(WebSockets.MESSAGE_EVENT, self.onMessage))

self.websocket:addEventListener(WebSockets.CLOSE_EVENT, self.onClose))

self.websocket:addEventListener(WebSockets.ERROR_EVENT, self.onError))

end

function MainScene:onSendTextClicked()

if not self.websocket then

print("not connected")

return

end

local text = "hello" .. tostring(math.random())

if self.websocket:send(text) then

printf("send text msg: %s",text)

end

end

function MainScene:onSendBinaryClicked()

if not self.websocket then

print("not connected")

return

end

local t = {}

for i = 1,math.random(4,8) do

t[#t + 1] = string.char(math.random(0,31))

end

local binary = table.concat(t)

if self.websocket:send(binary, WebSockets.BINARY_MESSAGE) then

printf("send binary msg: len = %d,string.len(binary), bin2hex(binary))

end

end

return MainScene

4.详解

MainScene类中主要的构造函数和其他处理函数。

构造函数创建3个Label分别是

Connect,send text,send binary.

该Label均可以点击，点击后分别调用

onConnectClicked,onSendTextClicked,onSendBinaryClicked函数。

其中：

onConnectClicked函数

判断是否才能在self.websocket变量，如果存在则返回，不存在则进行创建。

同时对创建返回的对象添加事件OPEN_EVENT，MESSAGE_EVENT，CLOSE_EVENT，ERROR_EVENT

具体如下：

if self.websocket then return end

self.websocket = WebSockets.new("ws://echo.websocket.org")

self.websocket:addEventListener(WebSockets.OPEN_EVENT, self.onopen))

self.websocket:addEventListener(WebSockets.MESSAGE_EVENT, self.onMessage))

self.websocket:addEventListener(WebSockets.CLOSE_EVENT, self.onClose))

self.websocket:addEventListener(WebSockets.ERROR_EVENT, self.onError))

事件对应的函数是onopen，onMessage，onClose，onError。

其中self.websocket = WebSockets.new("ws://echo.websocket.org") 命令是创建一个连接对象，地址"ws://echo.websocket.org"是测试网址。

这里主要需要介绍的是onMessage函数，该函数在接受到数据后调用，通过判断是否是BINARY_MESSAGE进行输出。

4.1onSendTextClicked函数

判断是否存在对象，如果存在则发送字符串。

4.2onSendBinaryClicked函数

同onSendTextClicked函数，不过发送的是二进制文件。