ExtendedPropertyEnumerator.Current 属性

定义

命名空间:

Microsoft.SqlServer.Dts.Runtime

程序集:

Microsoft.SqlServer.ManagedDTS.dll

返回集合中的当前 ExtendedProperty 对象。

public:
 property Microsoft::SqlServer::Dts::Runtime::ExtendedProperty ^ Current { Microsoft::SqlServer::Dts::Runtime::ExtendedProperty ^ get(); };

public Microsoft.SqlServer.Dts.Runtime.ExtendedProperty Current { get; }

member this.Current : Microsoft.SqlServer.Dts.Runtime.ExtendedProperty

Public ReadOnly Property Current As ExtendedProperty

属性值

ExtendedProperty

当前 ExtendedProperty 对象。

示例

以下代码示例创建一个枚举器，然后使用 Current 和 MoveNext 方法来浏览集合。

using System;  
using System.Collections.Generic;  
using System.Text;  
using Microsoft.SqlServer.Dts.Runtime;  
namespace ExtendedProperties_Testing  
{  
    class Program  
    {  
        static void Main(string[] args)  
        {  
            // The package is one of the SSIS Samples.  
            string mySample = @"C:\Program Files\Microsoft SQL Server\100\Tools\Samples\1033\DataTransformationServices\Package Samples\CalculatedColumns Sample\CalculatedColumns\CalculatedColumns.dtsx";  
            // Create the Application, and load the sample.  
            Application app = new Application();  
            Package pkg = app.LoadPackage(mySample, null);  

            // Get the Extended properties collection from the package.  
            ExtendedProperties myExtProps = pkg.ExtendedProperties;  
            //Create the Enumerator.  
            ExtendedPropertyEnumerator myEnumerator = myExtProps.GetEnumerator();  

            Console.WriteLine("The collection contains the following values:");  
            int i = 0;  
            ExtendedProperty myExtProp;  
            while ((myEnumerator.MoveNext()) && (myEnumerator.Current != null))  
            {  
                myExtProp = (ExtendedProperty)myEnumerator.Current;  
                Console.WriteLine("[{0}] {1}, {2}", i++, myExtProp.ID, myExtProp.DataType);  
                Console.WriteLine("------------------------------");  
            }  
            // Reset puts the index pointer before the beginning.  
            // Do not retrieve from the collection until MoveNext is called.  
            myEnumerator.Reset();  
            myEnumerator.MoveNext();  

            // Now that the enumerator has been reset, and moved to the  
            // first item in the collection, show the first item.  
            myExtProp = (ExtendedProperty)myEnumerator.Current;  
            Console.WriteLine("The first item in the enumerator after Reset:");  
            Console.WriteLine("{0}, {1}", myExtProp.ID, myExtProp.DataType);  
            Console.WriteLine();  
        }  
    }  
}  

Imports System  
Imports System.Collections.Generic  
Imports System.Text  
Imports Microsoft.SqlServer.Dts.Runtime  

Namespace ExtendedProperties_Testing  
    Class Program  
        Shared  Sub Main(ByVal args() As String)  
            ' The package is one of the SSIS Samples.  
            Dim mySample As String =  "C:\Program Files\Microsoft SQL Server\100\Tools\Samples\1033\DataTransformationServices\Package Samples\CalculatedColumns Sample\CalculatedColumns\CalculatedColumns.dtsx"   
            ' Create the Application, and load the sample.  
            Dim app As Application =  New Application()   
            Dim pkg As Package =  app.LoadPackage(mySample,Nothing)   

            ' Get the Extended properties collection from the package.  
            Dim myExtProps As ExtendedProperties =  pkg.ExtendedProperties   
            'Create the Enumerator.  
            Dim myEnumerator As ExtendedPropertyEnumerator =  myExtProps.GetEnumerator()   

            Console.WriteLine("The collection contains the following values:")  
            Dim i As Integer =  0   
            Dim myExtProp As ExtendedProperty  
            While (myEnumerator.MoveNext()) &&(myEnumerator.Current <> Nothing)  
                myExtProp = CType(myEnumerator.Current, ExtendedProperty)  
                Console.WriteLine("[{0}] {1}, {2}",i = Console.WriteLine("[{0}] {1}, {2}",i + 1  
                Console.WriteLine("------------------------------")  
            End While  
            ' Reset puts the index pointer before the beginning.  
            ' Do not retrieve from the collection until MoveNext is called.  
            myEnumerator.Reset()  
            myEnumerator.MoveNext()  

            ' Now that the enumerator has been reset, and moved to the  
            ' first item in the collection, show the first item.  
            myExtProp = CType(myEnumerator.Current, ExtendedProperty)  
            Console.WriteLine("The first item in the enumerator after Reset:")  
            Console.WriteLine("{0}, {1}", myExtProp.ID, myExtProp.DataType)  
            Console.WriteLine()  
        End Sub  
    End Class  
End Namespace  

示例输出：

该集合包含以下数值：

[0] {F3B7314E-DB1E-4CCA-A856-2E617A1B3265}，字符串

------------------------------

[1] {AA947F2D-C3B3-420F-B39E-4B7C77DAAFC0}，字符串

------------------------------

[2] {AB2CCC33-3090-4C36-B444-5B50BB481324}，字符串

------------------------------

[3] {FE85601C-4ECC-41D4-BEAA-1318DDF7EE2A}，弦

------------------------------

[4] {4D1641B9-94EF-4144-9820-1B30ABD2214F}，弦

------------------------------

[5] {4E76A01C-BFF8-462D-AAB0-FB48B3EEAE00}，弦

------------------------------

[6] {A56842E2-11C1-487E-B670-33F25B534146}，字符串

------------------------------

重置后枚举器的第一个项目：

{F3B7314E-DB1E-4CCA-A856-2E617A1B3265}，字符串

注解

在创建枚举器或调用 重置 方法后，必须调用 MoveNext 方法，将枚举子推进到集合的第一个元素，枚举器才能读取 当前 属性的值;否则， Current 未定义，并抛出异常。

如果最后一次调用 MoveNext，Currentfalse也会抛出异常，表示集合结束。

Current 不会移动枚举器的位置，连续调用 Current 返回相同对象，直到调用 MoveNext 或 Reset 。

只要集合保持不变，枚举器就保持有效。 如果对集合进行了更改，比如添加、修改或删除元素，枚举器将失效并无法恢复;因此，下一次调用 MoveNext 或 Reset 会抛出 InvalidOperationException。 如果集合在调用 MoveNext 和 Current 之间被修改， Current 会返回它被设定的元素，即使枚举器已被废止。