使用包裝的 XmlReader 物件進行驗證

更新： November 2007

您可以建立由另一個 XmlReader 物件包裝的新 XmlReader 物件。這可讓您在另一個 XmlReader 物件的頂端加入其他功能。例如，XmlNodeReader 類別不支援資料驗證。藉由建立包裝 XmlNodeReader 物件的 XmlReader 物件，您就可以驗證 XmlNodeReader 物件中儲存的資料。

範例

在下列範例中，會將 XML 檔案載入至 XML 文件，並進行修改。將 XML 文件傳遞至 XmlNodeReader，其稍後會傳遞至 XmlReader.Create 方法。當驗證讀取器剖析檔案時，其可驗證對 XML 檔案所做的任何變更。

Imports System
Imports System.Xml
Imports System.Xml.Schema
Imports System.IO

public class Sample 

  public shared sub Main() 

    ' Create and load the XML document.
    Dim doc as XmlDocument = new XmlDocument()
    doc.Load("booksSchema.xml")

    ' Make changes to the document.
    Dim book as XmlElement
    book = CType(doc.DocumentElement.FirstChild, XmlElement)
    book.SetAttribute("publisher", "Worldwide Publishing")

    ' Create an XmlNodeReader using the XML document.
    Dim nodeReader as XmlNodeReader = new XmlNodeReader(doc)

    ' Set the validation settings on the XmlReaderSettings object.
    Dim settings as XmlReaderSettings = new XmlReaderSettings()
    settings.ValidationType = ValidationType.Schema
    settings.Schemas.Add("urn:bookstore-schema", "books.xsd")
    AddHandler settings.ValidationEventHandler, AddressOf ValidationCallBack

    ' Create a validating reader that wraps the XmlNodeReader object.
    Dim reader as XmlReader = XmlReader.Create(nodeReader,settings)

    ' Parse the XML file.
    while (reader.Read())
    end while
  end sub

  ' Display any validation errors.
  private shared sub ValidationCallBack(sender as object, e as ValidationEventArgs)
    Console.WriteLine("Validation Error: {0}", e.Message)
  end sub

end class

using System;
using System.Xml;
using System.Xml.Schema;
using System.IO;

public class Sample {

  public static void Main() {

    // Create and load the XML document.
    XmlDocument doc = new XmlDocument();
    doc.Load("booksSchema.xml");

    // Make changes to the document.
    XmlElement book = (XmlElement) doc.DocumentElement.FirstChild;
    book.SetAttribute("publisher", "Worldwide Publishing");

    // Create an XmlNodeReader using the XML document.
    XmlNodeReader nodeReader = new XmlNodeReader(doc);

    // Set the validation settings on the XmlReaderSettings object.
    XmlReaderSettings settings = new XmlReaderSettings();
    settings.ValidationType = ValidationType.Schema;
    settings.Schemas.Add("urn:bookstore-schema", "books.xsd");
    settings.ValidationEventHandler += new ValidationEventHandler (ValidationCallBack);

   // Create a validating reader that wraps the XmlNodeReader object.
   XmlReader reader = XmlReader.Create(nodeReader, settings);

   // Parse the XML file.
   while (reader.Read());
  }

  // Display any validation errors.
  private static void ValidationCallBack(object sender, ValidationEventArgs e) {
    Console.WriteLine("Validation Error: {0}", e.Message);
  }
}

輸入

使用下列檔案做為輸入。

bookSchema.xml

<?xml version='1.0'?>
<bookstore xmlns="urn:bookstore-schema">
  <book genre="autobiography">
    <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">
    <title>The Confidence Man</title>
    <author>
      <first-name>Herman</first-name>
      <last-name>Melville</last-name>
    </author>
    <price>11.99</price>
  </book>
</bookstore>

books.xsd

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"
    xmlns="urn:bookstore-schema"
    elementFormDefault="qualified"
    targetNamespace="urn:bookstore-schema">

 <xsd:element name="bookstore" type="bookstoreType"/>

 <xsd:complexType name="bookstoreType">
  <xsd:sequence maxOccurs="unbounded">
   <xsd:element name="book"  type="bookType"/>
  </xsd:sequence>
 </xsd:complexType>

 <xsd:complexType name="bookType">
  <xsd:sequence>
   <xsd:element name="title" type="xsd:string"/>
   <xsd:element name="author" type="authorName"/>
   <xsd:element name="price"  type="xsd:decimal"/>
  </xsd:sequence>
  <xsd:attribute name="genre" type="xsd:string"/>
 </xsd:complexType>

 <xsd:complexType name="authorName">
  <xsd:sequence>
   <xsd:element name="first-name"  type="xsd:string"/>
   <xsd:element name="last-name" type="xsd:string"/>
  </xsd:sequence>
 </xsd:complexType>

</xsd:schema>

輸出

驗證錯誤：未宣告 publisher 屬性。

請參閱

概念

使用 XmlReader 讀取 XML

其他資源

使用 XmlReader 驗證 XML 資料