c#打印機脫機檢查及阻塞打印

在使用winform編寫自動打印服務的過程中，發現只要進行了打印命令的調用，文檔就會進入到打印等待隊列，如果打印機無法正常工作，則會影響到相關業務數據的正確轉換，所以需要檢查打印機的狀態來保障每次打印時打印機處於空閑狀態，打印時隊列中也只能有一個文檔，本文是通過引用System.Management來實現對打印機狀態的查詢

打印機狀態獲取

        enum PrinterStatus
        {
            其他 = 1,
            未知 = 2,
            空閑 = 3,
            打印 = 4,
            預熱 = 5,
            停止打印 = 6,
            脫機 = 7,
        }

        /// <summary>
        /// 獲取打印機的當前狀態
        /// </summary>
        /// <param name="PrinterDevice">打印機設備名稱</param>
        /// <returns>打印機狀態</returns>
        private static PrinterStatus GetPrinterPrinterStatus(string PrinterDevice)
        {
            PrinterStatus ret = 0;
            string path = @"win32_printer.DeviceId='" + PrinterDevice + "'";
            ManagementObject printer = new ManagementObject(path);
            printer.Get();
            ret = (PrinterStatus)Convert.ToInt32(printer.Properties["PrinterStatus"].Value);
            return ret;
        }

打印機脫機檢查

        public static bool CheckPrinter(string BindPrintName)
        {
            ManagementScope scope = new ManagementScope(@"\root\cimv2");
            scope.Connect();

            // Select Printers from WMI Object Collections
            ManagementObjectSearcher searcher = new ManagementObjectSearcher("SELECT * FROM Win32_Printer");

            string printerName = "";
            foreach (ManagementObject printer in searcher.Get())
            {
                printerName = printer["Name"].ToString().ToLower();
                if (printerName.IndexOf(BindPrintName.ToLower()) > -1)
                {
                    //foreach (var property in printer.Properties)
                    //{
                    //    LogUtil.WriteLog(property.Name + ":" + property.Value);
                    //}
                    if (printer["WorkOffline"].ToString().ToLower().Equals("true"))
                    {
                        return false;
                    }
                    else
                    {
                        return true;
                    }
                }
            }
            return false;
        }

 

打印機阻塞隊列實現

這里主要是通過一個while循環來不停的獲取打印機的狀態，空閑時才會進行下一次打印，通過兩個標志位來配合輪詢的外部介入退出

FinishWait標志位是任務內部的標識，如果打印機檢查到了錯誤狀態則進行輪詢退出

GlobalInfo.IsGlobalExist標志位是程序全局標識，如果界面上通知用戶等待時間過長，可以進行人工手動干預退出

                    //檢查打印機狀態
                    if (!CheckPrinter(PrintName))
                    {
                        throw new PrintCheckException("打印機處於脫機狀態");
                    }
                    PrinterStatus State = GetPrinterPrinterStatus(PrintName);
                    if (State == PrinterStatus.空閑)
                    {

                    }
                    else if (State == PrinterStatus.打印 || State == PrinterStatus.預熱)
                    {
                        //正在打印/預熱時循環去查詢打印機狀態，如果變成了就緒就開始打印
                        while (State != PrinterStatus.空閑 && !FinishWait && !GlobalInfo.IsGlobalExist)
                        {
                            State = GetPrinterPrinterStatus(PrintName);
                            if (!CheckPrinter(PrintName))
                            {
                                FinishWait = true;
                                throw new PrintCheckException("打印機處於脫機狀態");
                            }
                            if (State == PrinterStatus.打印 || State == PrinterStatus.預熱 || State == PrinterStatus.空閑)
                            {
                                if (State == PrinterStatus.空閑)
                                {

                                    FinishWait = true;
                                }
                            }
                            else
                            {
                                FinishWait = true;
                                throw new PrintCheckException("打印機狀態錯誤，當前狀態：" + State.ToString());
                            }
                        }