请教下面的代码！

Question

using System;using System.Collections.Generic;using System.Text;using System.Management;using System.Net;namespace testPrintJobArrival{public delegate void PrintJobArrived(object sender, ManagementBaseObject printProperties);public class WMIPrinter{ConnectionOptions _co = new ConnectionOptions();internal static System.Management.ManagementScope _ms = null;private const string PRINTERJOBS = "SELECT * FROM Win32_PrintJob";private const string PRINTERS = "SELECT * FROM Win32_Printer";private const int QUERYINTERVAL = 1;public PrintJobArrived OnPrintJobArrived = null;private System.Management.ManagementEventWatcher _printEventWatcher = null;private ManagementObjectSearcher _moSearchPrintJobs = null;public WMIPrinter(){ //Point to machine_co.EnablePrivileges = true;_co.Impersonation = ImpersonationLevel.Delegate;_ms = new System.Management.ManagementScope("\\\\localhost\\root\\cimv2", _co);_moSearchPrintJobs = new ManagementObjectSearcher(PRINTERJOBS);}public void StartPrintWatcher(){_printEventWatcher = new System.Management.ManagementEventWatcher();_printEventWatcher.Query = new System.Management.EventQuery("SELECT * FROM __InstanceCreationEvent WITHIN " + QUERYINTERVAL + " WHERE TargetInstance ISA \"Win32_PrintJob\"");string hostName = Dns.GetHostName();this._printEventWatcher.Scope = new System.Management.ManagementScope("\\\\" + hostName + "\\root\\CIMV2");_printEventWatcher.EventArrived += new EventArrivedEventHandler(this.Arrived); _printEventWatcher.Start(); //asynchronous//_printEventWatcher.WaitForNextEvent(); //synchronous}public void StopPrintWatcher(){if (_printEventWatcher != null)_printEventWatcher.Stop();}/// <summary>/// new Print Job has Arrived.../// </summary>/// <param name="sender"></param>/// <param name="e"></param>public void Arrived(object sender, EventArrivedEventArgs e){foreach (PropertyData pd in e.NewEvent.Properties){ManagementBaseObject mbo = pd.Value as ManagementBaseObject;if (mbo != null){//mbo.Properties[""]if (OnPrintJobArrived != null)OnPrintJobArrived(this, mbo);}}}}}
上面delegate 的使用有问题！

Answer 1

zgke 做过吗？？事件检测不到啊。？？

Answer 2

在提出有关delegate 的问题之前，请先了解C里面的函数指针类型的用法……放到C#中，换了个叫法，叫做delegate

Answer 3

zgke  做过吗？？ 打印事件检测不到啊？？？

Answer 4

这段代码我是从网上搜到的，正在看
_printEventWatcher.EventArrived += new EventArrivedEventHandler(this.Arrived);这句有哪位请解释一下!!

Answer 5

_printEventWatcher.EventArrived += new EventArrivedEventHandler(this.Arrived);
在Arrived函数中
public void Arrived(object sender, EventArrivedEventArgs e){
   foreach (PropertyData pd in e.NewEvent.Properties)
   {
       ManagementBaseObject mbo = pd.Value as ManagementBaseObject;
       if (mbo != null)
       {
          if (OnPrintJobArrived != null)
          OnPrintJobArrived(this, mbo);    
          这里是怎么调用的，请解释一下？？
       }
   }
}

Answer 6

OnPrintJobArrived(this, mbo);    
          [这里是怎么调用的，请解释一下？？

Answer 7

EventArrivedEventArgs e 里面那个属性是表示当前事件的？？

Answer 8

delegate 是委托 建议装个msdn 看看一些用法