XmlArrayAttribute 类

定义

命名空间:

System.Xml.Serialization

程序集:

netstandard.dll, System.Xml.XmlSerializer.dll

Source:

XmlArrayAttribute.cs

指定 XmlSerializer 必须将特定类成员序列化为 XML 元素数组。

public ref class XmlArrayAttribute : Attribute

[System.AttributeUsage(System.AttributeTargets.Field | System.AttributeTargets.Parameter | System.AttributeTargets.Property | System.AttributeTargets.ReturnValue, AllowMultiple=false)]
public class XmlArrayAttribute : Attribute

[<System.AttributeUsage(System.AttributeTargets.Field | System.AttributeTargets.Parameter | System.AttributeTargets.Property | System.AttributeTargets.ReturnValue, AllowMultiple=false)>]
type XmlArrayAttribute = class
    inherit Attribute

Public Class XmlArrayAttribute
Inherits Attribute

继承

Object

Attribute

XmlArrayAttribute

属性

AttributeUsageAttribute

示例

以下示例将类实例序列化为包含多个对象数组的 XML 文档。 应用于 XmlArrayAttribute 成为 XML 元素数组的成员。

using System;
using System.IO;
using System.Xml.Serialization;
using System.Xml;

public class Run
{
   public static void Main()
   {
      Run test = new Run();
      test.SerializeDocument("books.xml");
   }

   public void SerializeDocument(string filename)
   {
      // Creates a new XmlSerializer.
      XmlSerializer s =
      new XmlSerializer(typeof(MyRootClass));

      // Writing the file requires a StreamWriter.
      TextWriter myWriter= new StreamWriter(filename);

      // Creates an instance of the class to serialize.
      MyRootClass myRootClass = new MyRootClass();

      /* Uses a basic method of creating an XML array: Create and
      populate a string array, and assign it to the
      MyStringArray property. */

      string [] myString = {"Hello", "world", "!"};
      myRootClass.MyStringArray = myString;

      /* Uses a more advanced method of creating an array:
         create instances of the Item and BookItem, where BookItem
         is derived from Item. */
      Item item1 = new Item();
      BookItem item2 = new BookItem();

      // Sets the objects' properties.
      item1.ItemName = "Widget1";
      item1.ItemCode = "w1";
      item1.ItemPrice = 231;
      item1.ItemQuantity = 3;

      item2.ItemCode = "w2";
      item2.ItemPrice = 123;
      item2.ItemQuantity = 7;
      item2.ISBN = "34982333";
      item2.Title = "Book of Widgets";
      item2.Author = "John Smith";

      // Fills the array with the items.
      Item [] myItems = {item1,item2};

      // Sets the class's Items property to the array.
      myRootClass.Items = myItems;

      /* Serializes the class, writes it to disk, and closes
         the TextWriter. */
      s.Serialize(myWriter, myRootClass);
      myWriter.Close();
   }
}

// This is the class that will be serialized.
public class MyRootClass
{
   private Item [] items;

   /* Here is a simple way to serialize the array as XML. Using the
      XmlArrayAttribute, assign an element name and namespace. The
      IsNullable property determines whether the element will be
      generated if the field is set to a null value. If set to true,
      the default, setting it to a null value will cause the XML
      xsi:null attribute to be generated. */
   [XmlArray(ElementName = "MyStrings",
   Namespace = "http://www.cpandl.com", IsNullable = true)]
   public string[] MyStringArray;

   /* Here is a more complex example of applying an
      XmlArrayAttribute. The Items property can contain both Item
      and BookItem objects. Use the XmlArrayItemAttribute to specify
      that both types can be inserted into the array. */
   [XmlArrayItem(ElementName= "Item",
   IsNullable=true,
   Type = typeof(Item),
   Namespace = "http://www.cpandl.com"),
   XmlArrayItem(ElementName = "BookItem",
   IsNullable = true,
   Type = typeof(BookItem),
   Namespace = "http://www.cohowinery.com")]
   [XmlArray]
   public Item []Items
   {
      get{return items;}
      set{items = value;}
   }
}

public class Item{
   [XmlElement(ElementName = "OrderItem")]
   public string ItemName;
   public string ItemCode;
   public decimal ItemPrice;
   public int ItemQuantity;
}

public class BookItem:Item
{
   public string Title;
   public string Author;
   public string ISBN;
}

Option Explicit
Option Strict

Imports System.IO
Imports System.Xml.Serialization
Imports System.Xml


Public Class Run
    
    Public Shared Sub Main()
        Dim test As New Run()
        test.SerializeDocument("books.xml")
    End Sub
    
    
    Public Sub SerializeDocument(ByVal filename As String)
        ' Creates a new XmlSerializer.
        Dim s As New XmlSerializer(GetType(MyRootClass))
        
        ' Writing the file requires a StreamWriter.
        Dim myWriter As New StreamWriter(filename)
        
        ' Creates an instance of the class to serialize. 
        Dim myRootClass As New MyRootClass()
        
        ' Uses a basic method of creating an XML array: Create and
        ' populate a string array, and assign it to the
        ' MyStringArray property. 
        
        Dim myString() As String =  {"Hello", "world", "!"}
        myRootClass.MyStringArray = myString
        
        ' Uses a more advanced method of creating an array:
        ' create instances of the Item and BookItem, where BookItem
        ' is derived from Item. 
        Dim item1 As New Item()
        Dim item2 As New BookItem()
        
        ' Sets the objects' properties.
        With item1
            .ItemName = "Widget1"
            .ItemCode = "w1"
            .ItemPrice = 231
            .ItemQuantity = 3
        End With

        With item2
            .ItemCode = "w2"
            .ItemPrice = 123
            .ItemQuantity = 7
            .ISBN = "34982333"
            .Title = "Book of Widgets"
            .Author = "John Smith"
        End With
        
        ' Fills the array with the items.
        Dim myItems() As Item =  {item1, item2}
        
        ' Set class's Items property to the array.
        myRootClass.Items = myItems
        
        ' Serializes the class, writes it to disk, and closes
        ' the TextWriter. 
        s.Serialize(myWriter, myRootClass)
        myWriter.Close()
    End Sub
End Class


' This is the class that will be serialized.
Public Class MyRootClass
    Private myItems() As Item
    
    ' Here is a simple way to serialize the array as XML. Using the
    ' XmlArrayAttribute, assign an element name and namespace. The
    ' IsNullable property determines whether the element will be
    ' generated if the field is set to a null value. If set to true,
    ' the default, setting it to a null value will cause the XML
    ' xsi:null attribute to be generated.
    <XmlArray(ElementName := "MyStrings", _
         Namespace := "http://www.cpandl.com", _
         IsNullable := True)> _
    Public MyStringArray() As String
    
    ' Here is a more complex example of applying an
    ' XmlArrayAttribute. The Items property can contain both Item
    ' and BookItem objects. Use the XmlArrayItemAttribute to specify
    ' that both types can be inserted into the array.
    <XmlArrayItem(ElementName := "Item", _
        IsNullable := True, _
        Type := GetType(Item), _
        Namespace := "http://www.cpandl.com"), _
     XmlArrayItem(ElementName := "BookItem", _
        IsNullable := True, _
        Type := GetType(BookItem), _
        Namespace := "http://www.cohowinery.com"), _
     XmlArray()> _
    Public Property Items As Item()
        Get
            Return myItems
        End Get
        Set
            myItems = value
        End Set
    End Property
End Class
 
Public Class Item
    <XmlElement(ElementName := "OrderItem")> _
    Public ItemName As String
    Public ItemCode As String
    Public ItemPrice As Decimal
    Public ItemQuantity As Integer
End Class

Public Class BookItem
    Inherits Item
    Public Title As String
    Public Author As String
    Public ISBN As String
End Class

注解

属于 XmlArrayAttribute 一系列属性，用于控制 XmlSerializer 如何序列化或反序列化对象。 有关类似属性的完整列表，请参阅 控制 XML 序列化的属性。

可以应用于 XmlArrayAttribute 返回对象数组的公共字段或读/写属性。 还可以将其应用于返回 ArrayList 实现 IEnumerable 接口的对象或任何字段的集合和字段。

将类成员应用于 XmlArrayAttribute 类成员时， Serialize 该类的方法 XmlSerializer 将从该成员生成 XML 元素的嵌套序列。 XML 架构文档（.xsd 文件）指示数组为 .complexType 例如，如果要序列化的类表示采购订单，则可以通过将返回表示订单项的对象数组应用于 XmlArrayAttribute 公共字段来生成已购买项目的数组。

如果未将任何属性应用于返回复杂或基元类型对象的数组的公共字段或属性，则默认情况下会 XmlSerializer 生成 XML 元素的嵌套序列。 若要更准确地控制生成的 XML 元素，请对字段或属性应用 a XmlArrayItemAttribute 和 A XmlArrayAttribute 。 例如，默认情况下，生成的 XML 元素的名称派生自成员标识符，可以通过设置 ElementName 属性来更改生成的 XML 元素的名称。

如果序列化包含特定类型的项和派生自该类型的所有类的数组，则必须使用该 XmlArrayItemAttribute 数组声明每种类型。

注释

可以在 XmlArray 代码中使用，而不是更长 XmlArrayAttribute的时间。

有关使用属性的详细信息，请参阅 “属性”。

构造函数

名称	说明
XmlArrayAttribute()	初始化 XmlArrayAttribute 类的新实例。
XmlArrayAttribute(String)	初始化类的新实例 XmlArrayAttribute ，并指定在 XML 文档实例中生成的 XML 元素名称。

属性

名称	说明
ElementName	获取或设置提供给序列化数组的 XML 元素名称。
Form	获取或设置一个值，该值指示由 XmlSerializer 该元素生成的 XML 元素名称是限定还是未限定。
IsNullable	获取或设置一个值，该值指示 XmlSerializer 必须将成员序列化为空 XML 标记，并将 xsi:nil 属性设置为 true。
Namespace	获取或设置 XML 元素的命名空间。
Order	获取或设置元素序列化或反序列化的显式顺序。
TypeId	在派生类中实现时，获取此 Attribute的唯一标识符。 (继承自 Attribute)

方法

名称	说明
Equals(Object)	返回一个值，该值指示此实例是否等于指定对象。 (继承自 Attribute)
GetHashCode()	返回此实例的哈希代码。 (继承自 Attribute)
GetType()	获取当前实例的 Type。 (继承自 Object)
IsDefaultAttribute()	在派生类中重写时，指示此实例的值是否为派生类的默认值。 (继承自 Attribute)
Match(Object)	在派生类中重写时，返回一个值，该值指示此实例是否等于指定对象。 (继承自 Attribute)
MemberwiseClone()	创建当前 Object的浅表副本。 (继承自 Object)
ToString()	返回一个表示当前对象的字符串。 (继承自 Object)

另请参阅

• XmlArray
• XmlArrayItemAttribute
• XmlAttributeOverrides
• XmlAttributes
• XML 序列化简介
• 如何：为 XML 流指定备用元素名称
• 使用属性控制 XML 序列化
• XML 序列化示例
• XML 架构定义工具 (Xsd.exe)