在使用winform编写自动打印服务的过程中，发现只要进行了打印命令的调用，文档就会进入到打印等待队列，如果打印机无法正常工作，则会影响到相关业务数据的正确转换，所以需要检查打印机的状态来保障每次打印时打印机处于空闲状态，打印时队列中也只能有一个文档，本文是通过引用System.Management来实现对打印机状态的查询
打印机状态获取
代码语言：javascript复制 enum PrinterStatus
{
其他 = 1,
未知 = 2,
空闲 = 3,
打印 = 4,
预热 = 5,
停止打印 = 6,
脱机 = 7,
}
/// <summary>
/// 获取打印机的当前状态
/// </summary>
/// <param name="PrinterDevice">打印机设备名称</param>
/// <returns>打印机状态</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;
}打印机脱机检查
代码语言：javascript复制 public static bool CheckPrinter(string BindPrintName)
{
ManagementScope scope = new ManagementScope(@"rootcimv2");
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;
}打印机阻塞队列实现
这里主要是通过一个while循环来不停的获取打印机的状态，空闲时才会进行下一次打印，通过两个标志位来配合轮询的外部介入退出
FinishWait标志位是任务内部的标识，如果打印机检查到了错误状态则进行轮询退出
GlobalInfo.IsGlobalExist标志位是程序全局标识，如果界面上通知用户等待时间过长，可以进行人工手动干预退出
代码语言：javascript复制 //检查打印机状态
if (!CheckPrinter(PrintName))
{
throw new PrintCheckException("打印机处于脱机状态");
}
PrinterStatus State = GetPrinterPrinterStatus(PrintName);
if (State == PrinterStatus.空闲)
{
}
else if (State == PrinterStatus.打印 || State == PrinterStatus.预热)
{
//正在打印/预热时循环去查询打印机状态，如果变成了就绪就开始打印
while (State != PrinterStatus.空闲 && !FinishWait && !GlobalInfo.IsGlobalExist)
{
State = GetPrinterPrinterStatus(PrintName);
if (!CheckPrinter(PrintName))
{
FinishWait = true;
throw new PrintCheckException("打印机处于脱机状态");
}
if (State == PrinterStatus.打印 || State == PrinterStatus.预热 || State == PrinterStatus.空闲)
{
if (State == PrinterStatus.空闲)
{
FinishWait = true;
}
}
else
{
FinishWait = true;
throw new PrintCheckException("打印机状态错误，当前状态：" State.ToString());
}
}
