XmlArrayItemAttribute 类

定义

表示指定 XmlSerializer 可以放置在序列化数组中的派生类型的特性。Represents an attribute that specifies the derived types that the XmlSerializer can place in a serialized array.

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

示例

下面的示例序列化一个名为的类 Group ,该类包含一个名为 Employees 的字段,该字段返回对象的数组 EmployeeThe following example serializes a class named Group that contains a field named Employees that returns an array of Employee objects. 该示例将应用 XmlArrayItemAttribute 到字段,从而指示 XmlSerializer 它可以插入基类的对象 (Employee) 类型和派生类类型 (Manager) 到序列化的数组中。The example applies the XmlArrayItemAttribute to the field, thereby instructing the XmlSerializer that it can insert objects of both the base class (Employee) type and derived class type (Manager) into the serialized array.

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

using namespace System;
using namespace System::IO;
using namespace System::Xml::Serialization;

public ref class Employee
{
public:
   String^ Name;
};

public ref class Manager: public Employee
{
public:
   int Level;
};

public ref class Group
{
public:

   /* The XmlArrayItemAttribute allows the XmlSerializer to insert
      both the base type (Employee) and derived type (Manager) 
      into serialized arrays. */

   [XmlArrayItem(Manager::typeid),
   XmlArrayItem(Employee::typeid)]
   array<Employee^>^Employees;

   /* Use the XmlArrayItemAttribute to specify types allowed
      in an array of Object items. */

   [XmlArray]
   [XmlArrayItem(Int32::typeid,
   ElementName="MyNumber"),
   XmlArrayItem(String::typeid,
   ElementName="MyString"),
   XmlArrayItem(Manager::typeid)]
   array<Object^>^ExtraInfo;
};

void SerializeObject( String^ filename )
{
   // Creates a new XmlSerializer.
   XmlSerializer^ s = gcnew XmlSerializer( Group::typeid );

   // Writing the XML file to disk requires a TextWriter.
   TextWriter^ writer = gcnew StreamWriter( filename );
   Group^ group = gcnew Group;
   Manager^ manager = gcnew Manager;
   Employee^ emp1 = gcnew Employee;
   Employee^ emp2 = gcnew Employee;
   manager->Name = "Consuela";
   manager->Level = 3;
   emp1->Name = "Seiko";
   emp2->Name = "Martina";
   array<Employee^>^emps = {manager,emp1,emp2};
   group->Employees = emps;

   // Creates an int and a string and assigns to ExtraInfo.
   array<Object^>^temp = {43,"Extra",manager};
   group->ExtraInfo = temp;

   // Serializes the object, and closes the StreamWriter.
   s->Serialize( writer, group );
   writer->Close();
}

void DeserializeObject( String^ filename )
{
   FileStream^ fs = gcnew FileStream( filename,FileMode::Open );
   XmlSerializer^ x = gcnew XmlSerializer( Group::typeid );
   Group^ g = dynamic_cast<Group^>(x->Deserialize( fs ));
   Console::WriteLine( "Members:" );
   System::Collections::IEnumerator^ myEnum = g->Employees->GetEnumerator();
   while ( myEnum->MoveNext() )
   {
      Employee^ e = safe_cast<Employee^>(myEnum->Current);
      Console::WriteLine( "\t{0}", e->Name );
   }
}

int main()
{
   SerializeObject( "TypeDoc.xml" );
   DeserializeObject( "TypeDoc.xml" );
}
using System;
using System.IO;
using System.Xml.Serialization;

public class Group
{
   /* The XmlArrayItemAttribute allows the XmlSerializer to insert
      both the base type (Employee) and derived type (Manager)
      into serialized arrays. */

   [XmlArrayItem(typeof(Manager)),
   XmlArrayItem(typeof(Employee))]
   public Employee[] Employees;

   /* Use the XmlArrayItemAttribute to specify types allowed
      in an array of Object items. */
   [XmlArray]
   [XmlArrayItem (typeof(int),
   ElementName = "MyNumber"),
   XmlArrayItem (typeof(string),
   ElementName = "MyString"),
   XmlArrayItem(typeof(Manager))]
   public object [] ExtraInfo;
}

public class Employee
{
   public string Name;
}

public class Manager:Employee{
   public int Level;
}

public class Run
{
   public static void Main()
   {
      Run test = new Run();
      test.SerializeObject("TypeDoc.xml");
      test.DeserializeObject("TypeDoc.xml");
   }

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

      // Writing the XML file to disk requires a TextWriter.
      TextWriter writer = new StreamWriter(filename);
      Group group = new Group();

      Manager manager = new Manager();
      Employee emp1 = new Employee();
      Employee emp2 = new Employee();
      manager.Name = "Consuela";
      manager.Level = 3;
      emp1.Name = "Seiko";
      emp2.Name = "Martina";
      Employee [] emps = new Employee[3]{manager, emp1, emp2};
      group.Employees = emps;

      // Creates an int and a string and assigns to ExtraInfo.
      group.ExtraInfo = new Object[3]{43, "Extra", manager};

      // Serializes the object, and closes the StreamWriter.
      s.Serialize(writer, group);
      writer.Close();
   }

   public void DeserializeObject(string filename)
   {
      FileStream fs = new FileStream(filename, FileMode.Open);
      XmlSerializer x = new XmlSerializer(typeof(Group));
      Group g = (Group) x.Deserialize(fs);
      Console.WriteLine("Members:");

      foreach(Employee e in g.Employees)
      {
         Console.WriteLine("\t" + e.Name);
      }
   }
}

Option Explicit
Option Strict

Imports System.IO
Imports System.Xml.Serialization

Public Class Group
    ' The XmlArrayItemAttribute allows the XmlSerializer to insert
    ' both the base type (Employee) and derived type (Manager)
    ' into serialized arrays. 
    
    <XmlArrayItem(GetType(Manager)), _
     XmlArrayItem(GetType(Employee))> _
    Public Employees() As Employee
    
    ' Use the XmlArrayItemAttribute to specify types allowed
    ' in an array of Object items. 
    <XmlArray(), _
     XmlArrayItem(GetType(Integer), ElementName := "MyNumber"), _
     XmlArrayItem(GetType(String), ElementName := "MyString"), _
     XmlArrayItem(GetType(Manager))> _
    Public ExtraInfo() As Object
End Class

Public Class Employee
    Public Name As String
End Class

Public Class Manager
    Inherits Employee
    Public Level As Integer
End Class


Public Class Run
    
    Public Shared Sub Main()
        Dim test As New Run()
        test.SerializeObject("TypeDoc.xml")
        test.DeserializeObject("TypeDoc.xml")
    End Sub
    
       
    Public Sub SerializeObject(ByVal filename As String)
        ' Creates a new XmlSerializer.
        Dim s As New XmlSerializer(GetType(Group))
        
        ' Writing the XML file to disk requires a TextWriter.
        Dim writer As New StreamWriter(filename)
        Dim group As New Group()
        
        Dim manager As New Manager()
        Dim emp1 As New Employee()
        Dim emp2 As New Employee()
        manager.Name = "Consuela"
        manager.Level = 3
        emp1.Name = "Seiko"
        emp2.Name = "Martina"
        Dim emps() As Employee = {manager, emp1, emp2}
        group.Employees = emps
        
        ' Creates an int and a string and assigns to ExtraInfo.
        group.ExtraInfo = New Object() {43, "Extra", manager}
        
        ' Serializes the object, and closes the StreamWriter.
        s.Serialize(writer, group)
        writer.Close()
    End Sub
    
    
    Public Sub DeserializeObject(ByVal filename As String)
        Dim fs As New FileStream(filename, FileMode.Open)
        Dim x As New XmlSerializer(GetType(Group))
        Dim g As Group = CType(x.Deserialize(fs), Group)
        Console.WriteLine("Members:")
        
        Dim e As Employee
        For Each e In  g.Employees
            Console.WriteLine(ControlChars.Tab & e.Name)
        Next e
    End Sub
End Class

注解

XmlArrayItemAttribute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 XmlArrayItemAttribute 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 XmlArrayItemAttribute 到任何返回数组的公共读/写成员,或提供对一个数组的访问。You can apply the XmlArrayItemAttribute to any public read/write member that returns an array, or provides access to one. 例如,返回对象数组、集合、 ArrayList 或实现接口的任何类的字段 IEnumerableFor example, a field that returns an array of objects, a collection, an ArrayList, or any class that implements the IEnumerable interface.

XmlArrayItemAttribute支持多态性,换言之,它允许将 XmlSerializer 派生的对象添加到数组中。The XmlArrayItemAttribute supports polymorphism--in other words, it allows the XmlSerializer to add derived objects to an array. 例如,假设名为的类 Mammal 派生自名为的基类 AnimalFor example, suppose a class named Mammal is derived from a base class named Animal. 进一步假设名为的类 MyAnimals 包含一个返回对象数组的字段 AnimalFurther suppose that a class named MyAnimals contains a field that returns an array of Animal objects. 若要允许 XmlSerializer 对和类型进行序列化 Animal Mammal ,请将应用 XmlArrayItemAttribute 到字段两次,每次指定两个可接受的类型之一。To allow the XmlSerializer to serialize both the Animal and Mammal type, apply the XmlArrayItemAttribute to the field twice, each time specifying one of the two acceptable types.

备注

可以应用的多个实例, XmlArrayItemAttribute 也可以 XmlElementAttribute 指定可插入到数组中的对象的类型。You can apply multiple instances of the XmlArrayItemAttribute or XmlElementAttribute to specify types of objects that can be inserted into the array.

备注

不支持对返回接口或接口数组的字段或属性进行序列化。The serialization of a field or property that returns an interface or array of interfaces is not supported.

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

备注

您可以 XmlArrayItem 在代码中使用该单词而不是更长的时间 XmlArrayItemAttributeYou can use the word XmlArrayItem in your code instead of the longer XmlArrayItemAttribute.

构造函数

XmlArrayItemAttribute()

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

XmlArrayItemAttribute(String)

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

XmlArrayItemAttribute(String, Type)

初始化 XmlArrayItemAttribute 类的新实例,并指定在 XML 文档中生成的 XML 元素的名称,以及可插入到所生成的 XML 文档中的 TypeInitializes a new instance of the XmlArrayItemAttribute class and specifies the name of the XML element generated in the XML document and the Type that can be inserted into the generated XML document.

XmlArrayItemAttribute(Type)

初始化 XmlArrayItemAttribute 类的新实例,并指定可插入到序列化数组中的 TypeInitializes a new instance of the XmlArrayItemAttribute class and specifies the Type that can be inserted into the serialized array.

属性

DataType

获取或设置生成的 XML 元素的 XML 数据类型。Gets or sets the XML data type of the generated XML element.

ElementName

获取或设置生成的 XML 元素的名称。Gets or sets the name of the generated XML element.

Form

获取或设置一个值,该值指示生成的 XML 元素的名称是否是限定的。Gets or sets a value that indicates whether the name of the generated XML element is qualified.

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

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

NestingLevel

获取或设置受 XmlArrayItemAttribute 影响的 XML 元素的层次结构中的级别。Gets or sets the level in a hierarchy of XML elements that the XmlArrayItemAttribute affects.

Type

获取或设置数组中允许的类型。Gets or sets the type allowed in an array.

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