public static void WWWFormWWWRequest(this WebRequest wwwUtil, string url, WWWForm form, DownLoadFinish finish, DownLoadError error = null)
    {
        FormWWWItem item = WWWItemPool.GetWWWItem <FormWWWItem>();

        if (item == null)
        {
            item = new FormWWWItem();
            WWWItemPool.AddWWWItem(item);
        }

        item.SetValue(url, form);
        item.downloadFinish = finish;
        item.downloadError  = error;

        wwwUtil.AddTask(item);
    }
    public static void WWWFormByteRequest(this WebRequest wwwUtil, string url, WWWForm form, DownLoadProgress progress, DownLoadData data, DownLoadError error = null)
    {
        FormWWWItem item = WWWItemPool.GetWWWItem <FormWWWItem>();

        if (item == null)
        {
            item = new FormWWWItem();
            WWWItemPool.AddWWWItem(item);
        }

        item.SetValue(url, form);
        item.downloadProgress = progress;
        item.downloadData     = data;
        item.downloadError    = error;

        wwwUtil.AddTask(item);
    }
    public static void WWWFormStringRequest(this WebRequest wwwUtil, string url, WWWForm form, BeginDownLoad begin, DownLoadText text, DownLoadError error = null)
    {
        FormWWWItem item = WWWItemPool.GetWWWItem <FormWWWItem>();

        if (item == null)
        {
            item = new FormWWWItem();
            WWWItemPool.AddWWWItem(item);
        }

        item.SetValue(url, form);
        item.beginDownload = begin;
        item.downloadText  = text;
        item.downloadError = error;

        wwwUtil.AddTask(item);
    }