ExtendedPropertyEnumerator.Current 属性
定义
重要
一些信息与预发行产品相关，相应产品在发行之前可能会进行重大修改。 对于此处提供的信息，Microsoft 不作任何明示或暗示的担保。
从集合返回当前的 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.ExtendedPropertyPublic ReadOnly Property Current As ExtendedProperty属性值
当前的 ExtendedProperty 对象。
示例
下面的代码示例创建一个枚举器，然后使用 Current MoveNext 方法在集合上导航。
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：
集合包含以下值：
[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}， 字符串
------------------------------
[4] {4D1641B9-94EF-4144-9820-1B30ABD2214F}， 字符串
------------------------------
[5] {4E76A01C-BFF8-462D-AAB0-FB48B3EEAE00}， 字符串
------------------------------
[6] {A56842E2-11C1-487E-B670-33F25B534146}， 字符串
------------------------------
重置后枚举器中的第一项：
{F3B7314E-DB1E-4CCA-A856-2E617A1B3265}， 字符串
注解
创建枚举器或调用 Reset 方法后，必须调用 MoveNext 方法才能将枚举器提升到集合的第一个元素，然后枚举器才能读取 Current 属性的值：否则， Current 未定义并引发异常。
如果返回false对 MoveNext 的最后一次调用，则 Current 也会引发异常，该调用指示集合的末尾。
当前 不会移动枚举器的位置，并且对 Current 的连续调用将返回相同的对象，直到调用 MoveNext 或 Reset 。
只要集合保持不变，枚举器就仍有效。 如果对集合进行了更改（例如添加、修改或删除元素），则枚举器将失效并变为不可恢复;因此，对 MoveNext 或 Reset 的下一次调用将引发 InvalidOperationException。 如果在对 MoveNext 和 Current 的调用之间修改了集合， 则 Current 将返回它设置为的元素，即使枚举器已失效。