XPathExpression 클래스
컴파일된 XPath 식을 나타내는 형식화된 클래스를 제공합니다.
네임스페이스: System.Xml.XPath
어셈블리: System.Xml(system.xml.dll)
구문
‘선언
Public MustInherit Class XPathExpression
‘사용 방법
Dim instance As XPathExpression
public abstract class XPathExpression
public ref class XPathExpression abstract
public abstract class XPathExpression
public abstract class XPathExpression
설명
이 클래스는 XPathNavigator 클래스에 있는 Compile 메서드의 결과로 반환됩니다. 이 클래스는 XPathNavigator 클래스의 Evaluate, Matches, Select 및 SelectSingleNode 메서드의 매개 변수로 사용합니다.
상속자 참고 사항 XPathExpression 클래스에서 상속하는 경우 다음과 같은 멤버를 재정의해야 합니다.
예제
다음 예제에서는 XPath 식의 처리 방법을 결정하기 위해 XPath 반환 형식을 사용하는 방법을 보여 줍니다.
Imports System
Imports System.Xml
Imports System.Xml.XPath
Public Class XPathExpressionExample
Public Shared Sub Main()
Dim document As XPathDocument = New XPathDocument("contosoBooks.xml")
Dim navigator As XPathNavigator = document.CreateNavigator()
Dim expression1 As XPathExpression = XPathExpression.Compile(".//bk:price/text()*10") ' Returns a number.
Dim expression2 As XPathExpression = XPathExpression.Compile("bk:bookstore/bk:book/bk:price") ' Returns a nodeset.
Dim manager As XmlNamespaceManager = New XmlNamespaceManager(navigator.NameTable)
manager.AddNamespace("bk", "https://www.contoso.com/books")
expression1.SetContext(manager)
expression2.SetContext(manager)
Evaluate(expression1, navigator)
Evaluate(expression2, navigator)
End Sub
Public Shared Sub Evaluate(ByVal expression As XPathExpression, ByVal navigator As XPathNavigator)
Select Case expression.ReturnType
Case XPathResultType.Number
Console.WriteLine(navigator.Evaluate(expression))
Exit Sub
Case XPathResultType.NodeSet
Dim nodes As XPathNodeIterator = navigator.Select(expression)
While nodes.MoveNext()
Console.WriteLine(nodes.Current.ToString())
End While
Case XPathResultType.Boolean
If CType(navigator.Evaluate(expression), Boolean) Then
Console.WriteLine("True!")
End If
Case XPathResultType.String
Console.WriteLine(navigator.Evaluate(expression))
End Select
End Sub
End Class
using System;
using System.Xml;
using System.Xml.XPath;
public class XPathExpressionExample
{
public static void Main()
{
XPathDocument document = new XPathDocument("contosoBooks.xml");
XPathNavigator navigator = document.CreateNavigator();
XPathExpression expression1 = XPathExpression.Compile(".//bk:price/text()*10"); // Returns a number.
XPathExpression expression2 = XPathExpression.Compile("bk:bookstore/bk:book/bk:price"); // Returns a nodeset.
XmlNamespaceManager manager = new XmlNamespaceManager(navigator.NameTable);
manager.AddNamespace("bk", "https://www.contoso.com/books");
expression1.SetContext(manager);
expression2.SetContext(manager);
Evaluate(expression1, navigator);
Evaluate(expression2, navigator);
}
public static void Evaluate(XPathExpression expression, XPathNavigator navigator)
{
switch (expression.ReturnType)
{
case XPathResultType.Number:
Console.WriteLine(navigator.Evaluate(expression));
break;
case XPathResultType.NodeSet:
XPathNodeIterator nodes = navigator.Select(expression);
while (nodes.MoveNext())
{
Console.WriteLine(nodes.Current.ToString());
}
break;
case XPathResultType.Boolean:
if ((bool)navigator.Evaluate(expression))
Console.WriteLine("True!");
break;
case XPathResultType.String:
Console.WriteLine(navigator.Evaluate(expression));
break;
}
}
}
public ref class Sample
{
public:
static void Evaluate( XPathExpression^ expr, XPathNavigator^ nav )
{
XPathNodeIterator^ i = nav->Select(expr);
switch ( expr->ReturnType )
{
case XPathResultType::Number:
Console::WriteLine( nav->Evaluate( expr ) );
break;
case XPathResultType::NodeSet:
while ( i->MoveNext() )
Console::WriteLine( i->Current );
break;
case XPathResultType::Boolean:
if ( *safe_cast<bool^>(nav->Evaluate( expr )) )
Console::WriteLine( "True!" );
break;
case XPathResultType::String:
Console::WriteLine( nav->Evaluate( expr ) );
break;
}
}
};
int main()
{
XPathDocument^ doc = gcnew XPathDocument( "books.xml" );
XPathNavigator^ nav = doc->CreateNavigator();
XPathExpression^ expr1 = nav->Compile( ".//price/text()*10" ); // Returns a number.
XPathExpression^ expr2 = nav->Compile( "bookstore/book/price" ); // Returns a nodeset.
Sample^ MySample = gcnew Sample;
MySample->Evaluate( expr1, nav );
MySample->Evaluate( expr2, nav );
}
XPathDocument doc = new XPathDocument("books.xml");
XPathNavigator nav = doc.CreateNavigator();
XPathExpression expr1 = nav.Compile(".//price/text()*10");
// Returns a number.
XPathExpression expr2 = nav.Compile("bookstore/book/price");
// Returns a nodeset.
Evaluate(expr1, nav);
Evaluate(expr2, nav);
} //main
public static void Evaluate(XPathExpression expr, XPathNavigator nav)
{
switch (expr.get_ReturnType()) {
case XPathResultType.Number:
Console.WriteLine(nav.Evaluate(expr));
break;
case XPathResultType.NodeSet:
XPathNodeIterator i = nav.Select(expr);
while (i.MoveNext()) {
Console.WriteLine(i.get_Current().ToString());
}
break;
case XPathResultType.Boolean:
if (System.Convert.ToBoolean(nav.Evaluate(expr))) {
Console.WriteLine("True!");
}
break;
case XPathResultType.String:
Console.WriteLine(nav.Evaluate(expr));
break;
}
} //Evaluate
이 예제에서는 contosoBooks.xml 파일을 입력으로 사용합니다.
<bookstore xmlns="https://www.contoso.com/books">
<book genre="autobiography" publicationdate="1981-03-22" ISBN="1-861003-11-0">
<title>The Autobiography of Benjamin Franklin</title>
<author>
<first-name>Benjamin</first-name>
<last-name>Franklin</last-name>
</author>
<price>8.99</price>
</book>
<book genre="novel" publicationdate="1967-11-17" ISBN="0-201-63361-2">
<title>The Confidence Man</title>
<author>
<first-name>Herman</first-name>
<last-name>Melville</last-name>
</author>
<price>11.99</price>
</book>
<book genre="philosophy" publicationdate="1991-02-15" ISBN="1-861001-57-6">
<title>The Gorgias</title>
<author>
<name>Plato</name>
</author>
<price>9.99</price>
</book>
</bookstore>
상속 계층 구조
System.Object
System.Xml.XPath.XPathExpression
스레드로부터의 안전성
이 형식의 모든 public static(Visual Basic의 경우 Shared) 멤버는 스레드로부터 안전합니다. 인터페이스 멤버는 스레드로부터 안전하지 않습니다.
플랫폼
Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
.NET Framework에서 모든 플래폼의 모든 버전을 지원하지는 않습니다. 지원되는 버전의 목록은 시스템 요구 사항을 참조하십시오.
버전 정보
.NET Framework
2.0, 1.1, 1.0에서 지원