在 DOM 中验证 XML 文档
默认情况下，在文档对象模型 (DOM) 中，XmlDocument 类不针对 XML 架构定义语言 (XSD) 架构或文档类型定义 (DTD) 验证 XML；只验证 XML 的格式是否正确。
要在 DOM 中验证 XML，可以在 XML 加载到 DOM 时进行验证，方法是将架构验证 XmlReader 传递给 Load 类的 XmlDocument 方法，也可以在 DOM 中使用 Validate 类的 XmlDocument 方法来验证以前未经过验证的 XML 文档。
在 XML 文档加载到 DOM 时进行验证
如果将验证 XmlDocument 传递给 XmlReader 类的 Load 方法，XmlDocument 类将在 XML 数据加载到 DOM 时对其进行验证。
成功验证之后，将应用架构的默认值，文本值根据需要转换为原子值，类型信息与经过验证的信息项关联。 因此，类型化 XML 数据将替换以前非类型化的 XML 数据。
创建 XML 架构验证 XmlReader
要创建 XML 架构验证 XmlReader，请执行下列步骤。
构造一个新的 XmlReaderSettings 实例。
将 XML 架构添加到 Schemas 实例的 XmlReaderSettings 属性中。
将
Schema指定为 ValidationType。可以选择指定 ValidationFlags 和 ValidationEventHandler，用于处理在验证期间遇到的架构验证错误和警告。
最后，将 XmlReaderSettings 对象与 XML 文档一起传递给 Create 类的 XmlReader 方法，创建架构验证 XmlReader。
示例
在下面的代码示例中，架构验证 XmlReader 验证加载到 DOM 的 XML 数据。 对 XML 文档进行无效的修改，然后重新验证文档，造成架构验证错误。 最后，更正其中一个错误，然后对 XML 文档的一部分进行部分验证。
#using <System.Xml.dll>
using namespace System;
using namespace System::Xml;
using namespace System::Xml::Schema;
ref class XmlDocumentValidationExample
{
public:
static void Main()
{
try
{
// Create a schema validating XmlReader.
XmlReaderSettings^ settings = gcnew XmlReaderSettings();
settings->Schemas->Add("http://www.contoso.com/books", "contosoBooks.xsd");
ValidationEventHandler^ eventHandler = gcnew ValidationEventHandler(ValidationEventHandlerOne);
settings->ValidationEventHandler += eventHandler;
settings->ValidationFlags = settings->ValidationFlags | XmlSchemaValidationFlags::ReportValidationWarnings;
settings->ValidationType = ValidationType::Schema;
XmlReader^ reader = XmlReader::Create("contosoBooks.xml", settings);
// The XmlDocument validates the XML document contained
// in the XmlReader as it is loaded into the DOM.
XmlDocument^ document = gcnew XmlDocument();
document->Load(reader);
// Make an invalid change to the first and last
// price elements in the XML document, and write
// the XmlSchemaInfo values assigned to the price
// element during load validation to the console.
XmlNamespaceManager^ manager = gcnew XmlNamespaceManager(document->NameTable);
manager->AddNamespace("bk", "http://www.contoso.com/books");
XmlNode^ priceNode = document->SelectSingleNode("/bk:bookstore/bk:book/bk:price", manager);
Console::WriteLine("SchemaInfo.IsDefault: {0}", priceNode->SchemaInfo->IsDefault);
Console::WriteLine("SchemaInfo.IsNil: {0}", priceNode->SchemaInfo->IsNil);
Console::WriteLine("SchemaInfo.SchemaElement: {0}", priceNode->SchemaInfo->SchemaElement);
Console::WriteLine("SchemaInfo.SchemaType: {0}", priceNode->SchemaInfo->SchemaType);
Console::WriteLine("SchemaInfo.Validity: {0}", priceNode->SchemaInfo->Validity);
priceNode->InnerXml = "A";
XmlNodeList^ priceNodes = document->SelectNodes("/bk:bookstore/bk:book/bk:price", manager);
XmlNode^ lastprice = priceNodes[priceNodes->Count - 1];
lastprice->InnerXml = "B";
// Validate the XML document with the invalid changes.
// The invalid changes cause schema validation errors.
document->Validate(eventHandler);
// Correct the invalid change to the first price element.
priceNode->InnerXml = "8.99";
// Validate only the first book element. The last book
// element is invalid, but not included in validation.
XmlNode^ bookNode = document->SelectSingleNode("/bk:bookstore/bk:book", manager);
document->Validate(eventHandler, bookNode);
}
catch (XmlException^ ex)
{
Console::WriteLine("XmlDocumentValidationExample.XmlException: {0}", ex->Message);
}
catch(XmlSchemaValidationException^ ex)
{
Console::WriteLine("XmlDocumentValidationExample.XmlSchemaValidationException: {0}", ex->Message);
}
catch (Exception^ ex)
{
Console::WriteLine("XmlDocumentValidationExample.Exception: {0}", ex->Message);
}
}
static void ValidationEventHandlerOne(Object^ sender, ValidationEventArgs^ args)
{
if (args->Severity == XmlSeverityType::Warning)
Console::Write("\nWARNING: ");
else if (args->Severity == XmlSeverityType::Error)
Console::Write("\nERROR: ");
Console::WriteLine(args->Message);
}
};
int main()
{
XmlDocumentValidationExample::Main();
return 0;
}
using System;
using System.Xml;
using System.Xml.Schema;
class XmlDocumentValidationExample
{
static void Main(string[] args)
{
try
{
// Create a schema validating XmlReader.
XmlReaderSettings settings = new XmlReaderSettings();
settings.Schemas.Add("http://www.contoso.com/books", "contosoBooks.xsd");
settings.ValidationEventHandler += new ValidationEventHandler(ValidationEventHandler);
settings.ValidationFlags = settings.ValidationFlags | XmlSchemaValidationFlags.ReportValidationWarnings;
settings.ValidationType = ValidationType.Schema;
XmlReader reader = XmlReader.Create("contosoBooks.xml", settings);
// The XmlDocument validates the XML document contained
// in the XmlReader as it is loaded into the DOM.
XmlDocument document = new XmlDocument();
document.Load(reader);
// Make an invalid change to the first and last
// price elements in the XML document, and write
// the XmlSchemaInfo values assigned to the price
// element during load validation to the console.
XmlNamespaceManager manager = new XmlNamespaceManager(document.NameTable);
manager.AddNamespace("bk", "http://www.contoso.com/books");
XmlNode priceNode = document.SelectSingleNode(@"/bk:bookstore/bk:book/bk:price", manager);
Console.WriteLine("SchemaInfo.IsDefault: {0}", priceNode.SchemaInfo.IsDefault);
Console.WriteLine("SchemaInfo.IsNil: {0}", priceNode.SchemaInfo.IsNil);
Console.WriteLine("SchemaInfo.SchemaElement: {0}", priceNode.SchemaInfo.SchemaElement);
Console.WriteLine("SchemaInfo.SchemaType: {0}", priceNode.SchemaInfo.SchemaType);
Console.WriteLine("SchemaInfo.Validity: {0}", priceNode.SchemaInfo.Validity);
priceNode.InnerXml = "A";
XmlNodeList priceNodes = document.SelectNodes(@"/bk:bookstore/bk:book/bk:price", manager);
XmlNode lastprice = priceNodes[priceNodes.Count - 1];
lastprice.InnerXml = "B";
// Validate the XML document with the invalid changes.
// The invalid changes cause schema validation errors.
document.Validate(ValidationEventHandler);
// Correct the invalid change to the first price element.
priceNode.InnerXml = "8.99";
// Validate only the first book element. The last book
// element is invalid, but not included in validation.
XmlNode bookNode = document.SelectSingleNode(@"/bk:bookstore/bk:book", manager);
document.Validate(ValidationEventHandler, bookNode);
}
catch (XmlException ex)
{
Console.WriteLine("XmlDocumentValidationExample.XmlException: {0}", ex.Message);
}
catch(XmlSchemaValidationException ex)
{
Console.WriteLine("XmlDocumentValidationExample.XmlSchemaValidationException: {0}", ex.Message);
}
catch (Exception ex)
{
Console.WriteLine("XmlDocumentValidationExample.Exception: {0}", ex.Message);
}
}
static void ValidationEventHandler(object sender, System.Xml.Schema.ValidationEventArgs args)
{
if (args.Severity == XmlSeverityType.Warning)
Console.Write("\nWARNING: ");
else if (args.Severity == XmlSeverityType.Error)
Console.Write("\nERROR: ");
Console.WriteLine(args.Message);
}
}
Imports System.Xml
Imports System.Xml.Schema
Class XmlDocumentValidationExample
Shared Sub Main()
Try
' Create a schema validating XmlReader.
Dim settings As XmlReaderSettings = New XmlReaderSettings()
settings.Schemas.Add("http://www.contoso.com/books", "contosoBooks.xsd")
AddHandler settings.ValidationEventHandler, New ValidationEventHandler(AddressOf ValidationEventHandler)
settings.ValidationFlags = settings.ValidationFlags And XmlSchemaValidationFlags.ReportValidationWarnings
settings.ValidationType = ValidationType.Schema
Dim reader As XmlReader = XmlReader.Create("contosoBooks.xml", settings)
' The XmlDocument validates the XML document contained
' in the XmlReader as it is loaded into the DOM.
Dim document As XmlDocument = New XmlDocument()
document.Load(reader)
' Make an invalid change to the first and last
' price elements in the XML document, and write
' the XmlSchemaInfo values assigned to the price
' element during load validation to the console.
Dim manager As XmlNamespaceManager = New XmlNamespaceManager(document.NameTable)
manager.AddNamespace("bk", "http://www.contoso.com/books")
Dim priceNode As XmlNode = document.SelectSingleNode("/bk:bookstore/bk:book/bk:price", manager)
Console.WriteLine("SchemaInfo.IsDefault: {0}", priceNode.SchemaInfo.IsDefault)
Console.WriteLine("SchemaInfo.IsNil: {0}", priceNode.SchemaInfo.IsNil)
Console.WriteLine("SchemaInfo.SchemaElement: {0}", priceNode.SchemaInfo.SchemaElement)
Console.WriteLine("SchemaInfo.SchemaType: {0}", priceNode.SchemaInfo.SchemaType)
Console.WriteLine("SchemaInfo.Validity: {0}", priceNode.SchemaInfo.Validity)
priceNode.InnerXml = "A"
Dim priceNodes As XmlNodeList = document.SelectNodes("/bk:bookstore/bk:book/bk:price", manager)
Dim lastprice As XmlNode = priceNodes(priceNodes.Count - 1)
lastprice.InnerXml = "B"
' Validate the XML document with the invalid changes.
' The invalid changes cause schema validation errors.
document.Validate(AddressOf ValidationEventHandler)
' Correct the invalid change to the first price element.
priceNode.InnerXml = "8.99"
' Validate only the first book element. The last book
' element is invalid, but not included in validation.
Dim bookNode As XmlNode = document.SelectSingleNode("/bk:bookstore/bk:book", manager)
document.Validate(AddressOf ValidationEventHandler, bookNode)
Catch ex As XmlException
Console.WriteLine("XmlDocumentValidationExample.XmlException: {0}", ex.Message)
Catch ex As XmlSchemaValidationException
Console.WriteLine("XmlDocumentValidationExample.XmlSchemaValidationException: {0}", ex.Message)
Catch ex As Exception
Console.WriteLine("XmlDocumentValidationExample.Exception: {0}", ex.Message)
End Try
End Sub
Shared Sub ValidationEventHandler(ByVal sender As Object, ByVal args As ValidationEventArgs)
If args.Severity = XmlSeverityType.Warning Then
Console.Write(vbCrLf & "WARNING: ")
Else
If args.Severity = XmlSeverityType.Error Then
Console.Write(vbCrLf & "ERROR: ")
End If
End If
Console.WriteLine(args.Message)
End Sub
End Class
该示例使用 contosoBooks.xml 文件作为输入。
<?xml version="1.0" encoding="utf-8" ?>
<bookstore xmlns="http://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>
该示例还使用 contosoBooks.xsd 文件作为输入。
<?xml version="1.0" encoding="utf-8"?>
<xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" targetNamespace="http://www.contoso.com/books" xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="bookstore">
<xs:complexType>
<xs:sequence>
<xs:element maxOccurs="unbounded" name="book">
<xs:complexType>
<xs:sequence>
<xs:element name="title" type="xs:string" />
<xs:element name="author">
<xs:complexType>
<xs:sequence>
<xs:element minOccurs="0" name="name" type="xs:string" />
<xs:element minOccurs="0" name="first-name" type="xs:string" />
<xs:element minOccurs="0" name="last-name" type="xs:string" />
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="price" type="xs:decimal" />
</xs:sequence>
<xs:attribute name="genre" type="xs:string" use="required" />
<xs:attribute name="publicationdate" type="xs:date" use="required" />
<xs:attribute name="ISBN" type="xs:string" use="required" />
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema>
如果在 XML 数据加载到 DOM 时进行验证，请考虑下列事项。
在上述示例中，每当遇到无效类型时就会调用 ValidationEventHandler。 如果 ValidationEventHandler 在验证 XmlReader 时未设置，则在任何属性或元素类型与验证架构中指定的相应类型不匹配的情况下调用 XmlSchemaValidationException 时会引发 Load。
如果 XML 文档加载到 XmlDocument 对象，并且具有关联的架构来定义默认值，XmlDocument 会像在 XML 文档中一样对待这些默认值。 这意味着，对于架构中的默认元素，IsEmptyElement 属性始终返回
false。 即使在 XML 文档中，也将编写为空元素。
在 DOM 中验证 XML 文档
Validate 类的 XmlDocument 方法针对 XmlDocument 对象的 Schemas 属性中的架构，验证加载到 DOM 的 XML 数据。 成功验证之后，将应用架构的默认值，文本值根据需要转换为原子值，类型信息与经过验证的信息项关联。 因此，类型化 XML 数据将替换以前非类型化的 XML 数据。
下面的示例与上面“在 XML 文档加载到 DOM 时进行验证”中的示例类似。 在此示例中，XML 文档不是在加载到 DOM 时进行验证，而是在加载到 DOM 之后，使用 Validate 类的 XmlDocument 方法进行验证。 Validate 方法针对 Schemas 的 XmlDocument 属性中包含的 XML 架构验证 XML 文档。 对 XML 文档进行无效的修改，然后重新验证文档，造成架构验证错误。 最后，更正其中一个错误，然后对 XML 文档的一部分进行部分验证。
using System;
using System.Xml;
using System.Xml.Schema;
class XmlDocumentValidationExample
{
static void Main(string[] args)
{
try
{
// Create a new XmlDocument instance and load
// the XML document into the DOM.
XmlDocument document = new XmlDocument();
document.Load("contosoBooks.xml");
// Add the XML schema for the XML document to the
// Schemas property of the XmlDocument.
document.Schemas.Add("http://www.contoso.com/books", "contosoBooks.xsd");
// Validate the XML document loaded into the DOM.
document.Validate(ValidationEventHandler);
// Make an invalid change to the first and last
// price elements in the XML document, and write
// the XmlSchemaInfo values assigned to the price
// element during validation to the console.
XmlNamespaceManager manager = new XmlNamespaceManager(document.NameTable);
manager.AddNamespace("bk", "http://www.contoso.com/books");
XmlNode priceNode = document.SelectSingleNode(@"/bk:bookstore/bk:book/bk:price", manager);
Console.WriteLine("SchemaInfo.IsDefault: {0}", priceNode.SchemaInfo.IsDefault);
Console.WriteLine("SchemaInfo.IsNil: {0}", priceNode.SchemaInfo.IsNil);
Console.WriteLine("SchemaInfo.SchemaElement: {0}", priceNode.SchemaInfo.SchemaElement);
Console.WriteLine("SchemaInfo.SchemaType: {0}", priceNode.SchemaInfo.SchemaType);
Console.WriteLine("SchemaInfo.Validity: {0}", priceNode.SchemaInfo.Validity);
priceNode.InnerXml = "A";
XmlNodeList priceNodes = document.SelectNodes(@"/bk:bookstore/bk:book/bk:price", manager);
XmlNode lastprice = priceNodes[priceNodes.Count - 1];
lastprice.InnerXml = "B";
// Validate the XML document with the invalid changes.
// The invalid changes cause schema validation errors.
document.Validate(ValidationEventHandler);
// Correct the invalid change to the first price element.
priceNode.InnerXml = "8.99";
// Validate only the first book element. The last book
// element is invalid, but not included in validation.
XmlNode bookNode = document.SelectSingleNode(@"/bk:bookstore/bk:book", manager);
document.Validate(ValidationEventHandler, bookNode);
}
catch (XmlException ex)
{
Console.WriteLine("XmlDocumentValidationExample.XmlException: {0}", ex.Message);
}
catch(XmlSchemaValidationException ex)
{
Console.WriteLine("XmlDocumentValidationExample.XmlSchemaValidationException: {0}", ex.Message);
}
catch (Exception ex)
{
Console.WriteLine("XmlDocumentValidationExample.Exception: {0}", ex.Message);
}
}
static void ValidationEventHandler(object sender, System.Xml.Schema.ValidationEventArgs args)
{
if (args.Severity == XmlSeverityType.Warning)
Console.Write("\nWARNING: ");
else if (args.Severity == XmlSeverityType.Error)
Console.Write("\nERROR: ");
Console.WriteLine(args.Message);
}
}
Imports System.Xml
Imports System.Xml.Schema
Class XmlDocumentValidationExample
Shared Sub Main()
Try
' Create a new XmlDocument instance and load
' the XML document into the DOM.
Dim document As XmlDocument = New XmlDocument()
document.Load("contosoBooks.xml")
' Add the XML schema for the XML document to the
' Schemas property of the XmlDocument.
document.Schemas.Add("http://www.contoso.com/books", "contosoBooks.xsd")
' Validate the XML document loaded into the DOM.
document.Validate(AddressOf ValidationEventHandler)
' Make an invalid change to the first and last
' price elements in the XML document, and write
' the XmlSchemaInfo values assigned to the price
' element during validation to the console.
Dim manager As XmlNamespaceManager = New XmlNamespaceManager(document.NameTable)
manager.AddNamespace("bk", "http://www.contoso.com/books")
Dim priceNode As XmlNode = document.SelectSingleNode("/bk:bookstore/bk:book/bk:price", manager)
Console.WriteLine("SchemaInfo.IsDefault: {0}", priceNode.SchemaInfo.IsDefault)
Console.WriteLine("SchemaInfo.IsNil: {0}", priceNode.SchemaInfo.IsNil)
Console.WriteLine("SchemaInfo.SchemaElement: {0}", priceNode.SchemaInfo.SchemaElement)
Console.WriteLine("SchemaInfo.SchemaType: {0}", priceNode.SchemaInfo.SchemaType)
Console.WriteLine("SchemaInfo.Validity: {0}", priceNode.SchemaInfo.Validity)
priceNode.InnerXml = "A"
Dim priceNodes As XmlNodeList = document.SelectNodes("/bk:bookstore/bk:book/bk:price", manager)
Dim lastprice As XmlNode = priceNodes(priceNodes.Count - 1)
lastprice.InnerXml = "B"
' Validate the XML document with the invalid changes.
' The invalid changes cause schema validation errors.
document.Validate(AddressOf ValidationEventHandler)
' Correct the invalid change to the first price element.
priceNode.InnerXml = "8.99"
' Validate only the first book element. The last book
' element is invalid, but not included in validation.
Dim bookNode As XmlNode = document.SelectSingleNode("/bk:bookstore/bk:book", manager)
document.Validate(AddressOf ValidationEventHandler, bookNode)
Catch ex As XmlException
Console.WriteLine("XmlDocumentValidationExample.XmlException: {0}", ex.Message)
Catch ex As XmlSchemaValidationException
Console.WriteLine("XmlDocumentValidationExample.XmlSchemaValidationException: {0}", ex.Message)
Catch ex As Exception
Console.WriteLine("XmlDocumentValidationExample.Exception: {0}", ex.Message)
End Try
End Sub
Shared Sub ValidationEventHandler(ByVal sender As Object, ByVal args As ValidationEventArgs)
If args.Severity = XmlSeverityType.Warning Then
Console.Write(vbCrLf & "WARNING: ")
Else
If args.Severity = XmlSeverityType.Error Then
Console.Write(vbCrLf & "ERROR: ")
End If
End If
Console.WriteLine(args.Message)
End Sub
End Class
该示例使用 contosoBooks.xml 和 contosoBooks.xsd 文件作为输入，这两个文件在上面的“在 XML 文档加载到 DOM 时进行验证”中提到。
处理验证错误和警告
XML 架构验证错误在验证加载到 DOM 的 XML 数据时报告。 会通知您在以下过程中发现的所有架构验证错误：在验证正在加载的 XML 数据的时，或在验证以前未经过验证的 XML 文档时。
验证错误由 ValidationEventHandler 进行处理。 如果 ValidationEventHandler 已分配给 XmlReaderSettings 实例或传递给 Validate 类的 XmlDocument 方法，ValidationEventHandler 将处理架构验证错误；否则，在遇到架构验证错误时，将引发 XmlSchemaValidationException。
注意
尽管遇到架构验证错误，XML 数据仍会加载到 DOM 中，ValidationEventHandler 引发异常来停止该进程时除外。
除非为 ReportValidationWarnings 对象指定了 XmlReaderSettings 标志，否则，不会报告架构验证警告。
有关说明 ValidationEventHandler 的示例，请参见上面的“在 XML 文档加载到 DOM 时进行验证”和“在 DOM 中验证 XML 文档”。
请参阅
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