c# - 使用 c# 和 WMI 计算客​​户端的打印页数

Question

目标就像我在主题中所说的那样。我知道有很多关于该特定问题的文章，我尝试了所有这些文章。但由于它们都不适合我，我现在正试图找出为什么这个只是工作有时，有时什么也没有发生，尽管打印了很多东西。所以这是我的代码，现在应该等待打印作业并告诉我它。而已。

private void StartMonitor()
    {

        try
        {
            var opt = new ConnectionOptions { EnablePrivileges = true };

            var scope = new ManagementScope("root\\CIMV2", opt);

            scope.Connect();

            var query = new WqlEventQuery("SELECT * FROM __InstanceOperationEvent WITHIN 60 WHERE TargetInstance ISA \"Win32_PrintJob\"");

            var watcher = new ManagementEventWatcher(query);

            Console.WriteLine("Ready to receive Printer Job events...");

            var pjEvent = watcher.WaitForNextEvent();

            if (pjEvent != null) Console.WriteLine("Event occured: " + pjEvent.Properties["PagesPrinted"]);
        }
        catch (ManagementException e)
        {
            Console.WriteLine(e.StackTrace);
            Console.WriteLine(e.ErrorCode);
            Console.WriteLine(e.ErrorInformation);
            _Error = e.Message;
            throw;
        }
    }

Answer 1

要获取特定作业的打印页面进度，请尝试使用较小的轮询间隔并使用 EventArrivedEventHandler附加到 WMI 事件的委托(delegate)以异步方式处理传入数据。

试试这个示例。

using System;
using System.Collections.Generic;
using System.Management;
using System.Text;


namespace GetWMI_Info
{
    public class EventWatcherAsync 
    {
        private void WmiEventHandler(object sender, EventArrivedEventArgs e)
        {
            Console.WriteLine("TargetInstance.Caption :         " + ((ManagementBaseObject)e.NewEvent.Properties["TargetInstance"].Value)["Caption"]);
            Console.WriteLine("TargetInstance.JobStatus :       " + ((ManagementBaseObject)e.NewEvent.Properties["TargetInstance"].Value)["JobStatus"]);
            Console.WriteLine("TargetInstance.PagesPrinted :    " + ((ManagementBaseObject)e.NewEvent.Properties["TargetInstance"].Value)["PagesPrinted"]);
            Console.WriteLine("TargetInstance.Status :          " + ((ManagementBaseObject)e.NewEvent.Properties["TargetInstance"].Value)["Status"]);

        }

        public EventWatcherAsync()
        {
            try
            {
                string ComputerName = "localhost";
                string WmiQuery;
                ManagementEventWatcher Watcher;
                ManagementScope Scope;   


                if (!ComputerName.Equals("localhost", StringComparison.OrdinalIgnoreCase)) 
                {
                    ConnectionOptions Conn = new ConnectionOptions();
                    Conn.Username  = "";
                    Conn.Password  = "";
                    Conn.Authority = "ntlmdomain:DOMAIN";
                    Scope = new ManagementScope(String.Format("\\\\{0}\\root\\CIMV2", ComputerName), Conn);
                }
                else
                    Scope = new ManagementScope(String.Format("\\\\{0}\\root\\CIMV2", ComputerName), null);
                Scope.Connect();

                WmiQuery ="Select * From __InstanceOperationEvent Within 1 "+
                "Where TargetInstance ISA 'Win32_PrintJob' ";

                Watcher = new ManagementEventWatcher(Scope, new EventQuery(WmiQuery));
                Watcher.EventArrived += new EventArrivedEventHandler(this.WmiEventHandler);
                Watcher.Start();
                Console.Read();
                Watcher.Stop();
            }
            catch (Exception e)
            {
                Console.WriteLine("Exception {0} Trace {1}", e.Message, e.StackTrace);
            }

        }

        public static void Main(string[] args)
        {
           Console.WriteLine("Listening {0}", "__InstanceOperationEvent");
           Console.WriteLine("Press Enter to exit");
           EventWatcherAsync eventWatcher = new EventWatcherAsync();
           Console.Read();
        }
    }
}