如何：在不使用反射的情况下获得打印系统对象属性

2011-08-12

使用反射列举对象的属性（以及这些属性的类型）会降低应用程序性能。 System.Printing.IndexedProperties 命名空间提供一种使用反射获取此信息的方法。

示例

执行如下步骤可以实现上述目的：

创建类型的实例。在下面的示例中，类型为 Microsoft .NET Framework附带的 PrintQueue 类型，但几近相同的代码也适用于您从 PrintSystemObject 派生的类型。
通过该类型的 PropertiesCollection 创建 PrintPropertyDictionary。此字典中每项的 Value 属性是从 PrintProperty 派生的类型之一的对象。
枚举字典的成员。对于每个成员，请执行下列操作。
将每项的值向上转换为 PrintProperty，并使用它来创建一个 PrintProperty 对象。
获取每个 PrintProperty 对象的 Value 的类型。


            ' Enumerate the properties, and their types, of a queue without using Reflection
            Dim localPrintServer As New LocalPrintServer()
            Dim defaultPrintQueue As PrintQueue = LocalPrintServer.GetDefaultPrintQueue()

            Dim printQueueProperties As PrintPropertyDictionary = defaultPrintQueue.PropertiesCollection

            Console.WriteLine("These are the properties, and their types, of {0}, a {1}", defaultPrintQueue.Name, defaultPrintQueue.GetType().ToString() + vbLf)

            For Each entry As DictionaryEntry In printQueueProperties
                Dim [property] As PrintProperty = CType(entry.Value, PrintProperty)

                If [property].Value IsNot Nothing Then
                    Console.WriteLine([property].Name & vbTab & "(Type: {0})", [property].Value.GetType().ToString())
                End If
            Next entry
            Console.WriteLine(vbLf & vbLf & "Press Return to continue...")
            Console.ReadLine()


            // Enumerate the properties, and their types, of a queue without using Reflection
            LocalPrintServer localPrintServer = new LocalPrintServer();
            PrintQueue defaultPrintQueue = LocalPrintServer.GetDefaultPrintQueue();

            PrintPropertyDictionary printQueueProperties = defaultPrintQueue.PropertiesCollection;

            Console.WriteLine("These are the properties, and their types, of {0}, a {1}", defaultPrintQueue.Name, defaultPrintQueue.GetType().ToString() +"\n");

            foreach (DictionaryEntry entry in printQueueProperties)
            {
                PrintProperty property = (PrintProperty)entry.Value;

                if (property.Value != null)
                {
                    Console.WriteLine(property.Name + "\t(Type: {0})", property.Value.GetType().ToString());
                }
            }
            Console.WriteLine("\n\nPress Return to continue...");
            Console.ReadLine();