XmlArrayAttribute 类

定义

指定 XmlSerializer 必须将特定的类成员序列化为 XML 元素的数组。Specifies that the XmlSerializer must serialize a particular class member as an array of XML elements.

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
public class XmlArrayAttribute : Attribute
[System.AttributeUsage(System.AttributeTargets.Field | System.AttributeTargets.Parameter | System.AttributeTargets.Property | System.AttributeTargets.ReturnValue)]
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
type XmlArrayAttribute = class
    inherit Attribute
[<System.AttributeUsage(System.AttributeTargets.Field | System.AttributeTargets.Parameter | System.AttributeTargets.Property | System.AttributeTargets.ReturnValue)>]
type XmlArrayAttribute = class
    inherit Attribute
Public Class XmlArrayAttribute
Inherits Attribute
继承
XmlArrayAttribute
属性

示例

下面的示例将类实例序列化为包含多个对象数组的 XML 文档。The following example serializes a class instance into an XML document that contains several object arrays. XmlArrayAttribute应用于成为 XML 元素数组的成员。The XmlArrayAttribute is applied to the members that become XML element arrays.

#using <System.Xml.dll>
#using <System.dll>

using namespace System;
using namespace System::IO;
using namespace System::Xml::Serialization;
using namespace System::Xml;
public ref class Item
{
public:

   [XmlElement(ElementName="OrderItem")]
   String^ ItemName;
   String^ ItemCode;
   Decimal ItemPrice;
   int ItemQuantity;
};

public ref class BookItem: public Item
{
public:
   String^ Title;
   String^ Author;
   String^ ISBN;
};

// This is the class that will be serialized.
public ref class MyRootClass
{
private:
   array<Item^>^items;

public:

   /* 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)]
   array<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=Item::typeid,
   Namespace="http://www.cpandl.com"),
   XmlArrayItem(ElementName="BookItem",
   IsNullable=true,
   Type=BookItem::typeid,
   Namespace="http://www.cohowinery.com")]
   [XmlArray]
   property array<Item^>^ Items 
   {
      array<Item^>^ get()
      {
         return items;
      }

      void set( array<Item^>^value )
      {
         items = value;
      }
   }
};

public ref class Run
{
public:
   void SerializeDocument( String^ filename )
   {
      // Creates a new XmlSerializer.
      XmlSerializer^ s = gcnew XmlSerializer( MyRootClass::typeid );

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

      // Creates an instance of the class to serialize. 
      MyRootClass^ myRootClass = gcnew MyRootClass;

      /* Uses a basic method of creating an XML array: Create and 
            populate a string array, and assign it to the 
            MyStringArray property. */
      array<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 = gcnew Item;
      BookItem^ item2 = gcnew 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.
      array<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();
   }
};

int main()
{
   Run^ test = gcnew Run;
   test->SerializeDocument( "books.xml" );
}
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

XmlArrayAttribute属于一系列属性,这些属性控制 XmlSerializer 序列化或反序列化对象的方式。The XmlArrayAttribute belongs to a family of attributes that controls how the XmlSerializer serializes or deserializes an object. 有关类似属性的完整列表,请参阅 控制 XML 序列化的属性For a complete list of similar attributes, see Attributes That Control XML Serialization.

你可以将应用 XmlArrayAttribute 到返回对象数组的公共字段或读/写属性。You can apply the XmlArrayAttribute to a public field or read/write property that returns an array of objects. 你还可以将其应用于返回 ArrayList 或任何返回实现接口的对象的字段的集合和字段 IEnumerableYou can also apply it to collections and fields that return an ArrayList or any field that returns an object that implements the IEnumerable interface.

将应用 XmlArrayAttribute 到类成员时, Serialize 类的方法 XmlSerializer 会从该成员生成嵌套的 XML 元素序列。When you apply the XmlArrayAttribute to a class member, the Serialize method of the XmlSerializer class generates a nested sequence of XML elements from that member. XML 架构文档 (.xsd 文件) ,表示这样的数组 complexTypeAn XML schema document (an .xsd file), indicates such an array as a complexType. 例如,如果要序列化的类表示采购订单,则可以通过 XmlArrayAttribute 将应用于返回表示订单项的对象的数组的公共字段,来生成购买项的数组。For example, if the class to be serialized represents a purchase order, you can generate an array of purchased items by applying the XmlArrayAttribute to a public field that returns an array of objects that represent order items.

如果没有属性应用于返回复杂或基元类型对象数组的公共字段或属性,则 XmlSerializer 默认情况下会生成一个嵌套的 XML 元素序列。If no attributes are applied to a public field or property that returns an array of complex or primitive type objects, the XmlSerializer generates a nested sequence of XML elements by default. 若要更精确地控制生成的 XML 元素,请将和应用于 XmlArrayItemAttribute XmlArrayAttribute 字段或属性。To more precisely control what XML elements are generated, apply an XmlArrayItemAttribute and an XmlArrayAttribute to the field or property. 例如,默认情况下,生成的 XML 元素的名称派生自成员标识符,可以通过设置属性来更改生成的 XML 元素的名称 ElementNameFor example, by default, the name of the generated XML element is derived from the member identifier You can change the name of the generated XML element by setting the ElementName property.

如果序列化的数组包含特定类型的项和从该类型派生的所有类,则必须使用 XmlArrayItemAttribute 来声明每个类型。If you serialize an array that contains items of a specific type and all the classes derived from that type, you must use the XmlArrayItemAttribute to declare each of the types.

备注

您可以 XmlArray 在代码中使用,而不是更长的时间 XmlArrayAttributeYou can use XmlArray in your code instead of the longer XmlArrayAttribute.

有关使用特性的详细信息,请参阅 特性For more information about using attributes, see Attributes.

构造函数

XmlArrayAttribute()

初始化 XmlArrayAttribute 类的新实例。Initializes a new instance of the XmlArrayAttribute class.

XmlArrayAttribute(String)

初始化 XmlArrayAttribute 类的新实例,并指定在 XML 文档实例中生成的 XML 元素名称。Initializes a new instance of the XmlArrayAttribute class and specifies the XML element name generated in the XML document instance.

属性

ElementName

获取或设置提供给序列化数组的 XML 元素名称。Gets or sets the XML element name given to the serialized array.

Form

获取或设置一个值,该值指示 XmlSerializer 生成的 XML 元素名称是限定的还是非限定的。Gets or sets a value that indicates whether the XML element name generated by the XmlSerializer is qualified or unqualified.

IsNullable

获取或设置一个值,该值指示 XmlSerializer 是否必须将成员序列化为 xsi:nil 属性设置为 true 的 XML 空标记。Gets or sets a value that indicates whether the XmlSerializer must serialize a member as an empty XML tag with the xsi:nil attribute set to true.

Namespace

获取或设置 XML 元素的命名空间。Gets or sets the namespace of the XML element.

Order

获取或设置序列化或反序列化元素的显式顺序。Gets or sets the explicit order in which the elements are serialized or deserialized.

TypeId

在派生类中实现时,获取此 Attribute 的唯一标识符。When implemented in a derived class, gets a unique identifier for this Attribute.

(继承自 Attribute)

方法

Equals(Object)

返回一个值,该值指示此实例是否与指定的对象相等。Returns a value that indicates whether this instance is equal to a specified object.

(继承自 Attribute)
GetHashCode()

返回此实例的哈希代码。Returns the hash code for this instance.

(继承自 Attribute)
GetType()

获取当前实例的 TypeGets the Type of the current instance.

(继承自 Object)
IsDefaultAttribute()

在派生类中重写时,指示此实例的值是否是派生类的默认值。When overridden in a derived class, indicates whether the value of this instance is the default value for the derived class.

(继承自 Attribute)
Match(Object)

当在派生类中重写时,返回一个指示此实例是否等于指定对象的值。When overridden in a derived class, returns a value that indicates whether this instance equals a specified object.

(继承自 Attribute)
MemberwiseClone()

创建当前 Object 的浅表副本。Creates a shallow copy of the current Object.

(继承自 Object)
ToString()

返回表示当前对象的字符串。Returns a string that represents the current object.

(继承自 Object)

显式接口实现

_Attribute.GetIDsOfNames(Guid, IntPtr, UInt32, UInt32, IntPtr)

将一组名称映射为对应的一组调度标识符。Maps a set of names to a corresponding set of dispatch identifiers.

(继承自 Attribute)
_Attribute.GetTypeInfo(UInt32, UInt32, IntPtr)

检索对象的类型信息,然后可以使用该信息获取接口的类型信息。Retrieves the type information for an object, which can be used to get the type information for an interface.

(继承自 Attribute)
_Attribute.GetTypeInfoCount(UInt32)

检索对象提供的类型信息接口的数量(0 或 1)。Retrieves the number of type information interfaces that an object provides (either 0 or 1).

(继承自 Attribute)
_Attribute.Invoke(UInt32, Guid, UInt32, Int16, IntPtr, IntPtr, IntPtr, IntPtr)

提供对某一对象公开的属性和方法的访问。Provides access to properties and methods exposed by an object.

(继承自 Attribute)

适用于

另请参阅