cocos2dx-lua从网络下载图片文件等

---------------------------------------以下是完整的文件下载类，代码开始了--------------------------------------------------

--文件下载，从网络上下载文件

local HttpFileDownLoad = class("HttpFileDownLoad")

--[[构造函数
    url:网络路径
    id:任务id，用于回调时区分任务
--]]

local mInstance = nil

function HttpFileDownLoad:getInstance()
    if mInstance == nil then
        mInstance = HttpFileDownLoad.new()
    end
    return mInstance
end

function HttpFileDownLoad:ctor()
    self:initData()
end

function HttpFileDownLoad:initData()
    self.status = "wait"
    self.path = nil
    self.parentFolder = "res"

    self:setSaveFolder("resource")
end

function HttpFileDownLoad:sendHttpRequest(url, id , callBackFunc)
    self.url = url
    self.id = id
    self.onCallBackFunc = callBackFunc

    self:execute()
end

function HttpFileDownLoad:setCallBackFunc(callBackFunc)
    self.onCallBackFunc = callBackFunc
end

--设置加载成功后的回调
function HttpFileDownLoad:onSuccess(func)
    self.onSuccessFunc = func
    return self
end

--设置加载失败后的回调
function HttpFileDownLoad:onError(func)
    self.onErrorFunc = func
    return self
end

--设置存储路径，需在execute之前执行，是否必须调用，可选，否则使用默认路径
function HttpFileDownLoad:setSaveFolder( folderName )
    self.path = device.writablePath .. self.parentFolder .. device.directorySeparator .. folderName
    print(" -- > img path : " , self.path)
    --创建默认缓存路径
    local isDirExist = cc.FileUtils:getInstance():isDirectoryExist(self.path)
    if not isDirExist then
        cc.FileUtils:getInstance():createDirectory(self.path)
    end
end

function HttpFileDownLoad:getFileCachePath(mUrl , folderPath)
    local urlTb = self:split_str(string.urldecode(mUrl), '/')
    local fileName = urlTb[#urlTb]
    return folderPath .. device.directorySeparator .. fileName
end

--图片加载任务执行
function HttpFileDownLoad:execute()
    self.status = "process"

    --1.设置文件缓存路径
    if not self.url then return self end
    local filePathName = self:getFileCachePath(self.url , self.path)
    print(" -- > img cache path : " , filePathName)

    local xhr = cc.XMLHttpRequest:new()
    xhr.responseType = cc.XMLHTTPREQUEST_RESPONSE_ARRAY_BUFFER
    xhr:open("GET", self.url)

    local function onReadyStateChanged()
        if xhr.readyState == 4 and (xhr.status >= 200 and xhr.status < 207) then
            print(" ---> img net load get response : " , xhr.statusText )
            local response   = xhr.response
            local strInfo = self:getStrData(response)
            io.writefile(filePathName, strInfo, "w+b")
            self:callback("down load ok" , filePathName)
        else
            print(" --- > error xhr.readyState is:", xhr.readyState, "xhr.status is: ",xhr.status)
            self:callbackErr(xhr.readyState, xhr.status)
        end
        xhr:unregisterScriptHandler()
    end

    xhr:registerScriptHandler(onReadyStateChanged)
    xhr:send()

    print(" -- > get net watting ... ")
    return self
end

--数据拆分，以没1024*5字节拆成一段，打包写入文件

function HttpFileDownLoad:getStrData(response)
    local totalSize = table.getn(response)
    local onePart = 1024*5
    local partData = ""
    local packTimes = math.floor(totalSize/onePart)

    print(" -- > pack size , times : " , totalSize , packTimes)
    for i=1,packTimes do
        local partUnPack = string.char(unpack(response,1+(i-1)*onePart , i*onePart) )
        partData = partData..partUnPack
        print(" -- > pack new part : " , 1+(i-1)*onePart , i*onePart)
    end
    print(" -- > pack end part : " , packTimes*onePart+1 , totalSize)
    local endUnpack = string.char(unpack(response , packTimes*onePart+1 , totalSize) )
    partData = partData..endUnpack
    return partData
end

--加载成功后的回调
function HttpFileDownLoad:callback(tex , filePathName)
    self.tex = tex
    self.status = "success"
    if self.onSuccessFunc then
        self.onSuccessFunc(tex, self.id)
    end
    if self.onCallBackFunc then
        self.onCallBackFunc(self.status , tex, filePathName , self.id)
    end
end

--加载失败后的回调
function HttpFileDownLoad:callbackErr(errCode, msg)    
    self.errCode = errCode
    self.msg = msg
    self.status = "error"
    if self.onErrorFunc then
        self.onErrorFunc(errCode, msg)
    end
    if self.onCallBackFunc then
        self.onCallBackFunc(self.status , errCode, msg)
    end
end

--拆分字符串的工具

function HttpFileDownLoad:split_str(str, delimiter)
    local resultStrsList = {}
    string.gsub(str, '[^' .. delimiter ..']+', function(w) table.insert(resultStrsList, w) end )
    return resultStrsList
end

return HttpFileDownLoad

---------------------------------------代码结束了--------------------------------------------------

调用方法：

HttpFileDownLoad:getInstance():sendHttpRequest(yourReqUrl, "tag_name" , handler(self , self.loadFileCallbackFunc))

--回调函数

function YourLayer:loadFileCallbackFunc( status , texture, filePath , id )
    local allFileNameTb = {"game_config.csv" , "move_config.csv" , "target_config.csv" }
    if status == "success" then
        if id == "tag_name" then
         --TODO ，download succ

        end
    elseif status == "error" then
        print(" -- > get net fail : " , texture, id)
    end
end