XmlSerializer 類別

定義

將物件序列化為 XML 文件,以及從 XML 文件將物件還原序列化。 XmlSerializer 可讓您控制如何將物件編碼為 XML。

public ref class XmlSerializer
public class XmlSerializer
type XmlSerializer = class
Public Class XmlSerializer
繼承
XmlSerializer

範例

下列範例包含兩個主要類別: PurchaseOrderTest 。 類別 PurchaseOrder 包含單一購買的相關資訊。 類別 Test 包含建立採購單的方法,以及讀取所建立的採購單。

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

using namespace System;
using namespace System::Xml;
using namespace System::Xml::Serialization;
using namespace System::IO;
ref class Address;
ref class OrderedItem;

/* The XmlRootAttribute allows you to set an alternate name 
   (PurchaseOrder) of the XML element, the element namespace; by 
   default, the XmlSerializer uses the class name. The attribute 
   also allows you to set the XML namespace for the element.  Lastly,
   the attribute sets the IsNullable property, which specifies whether 
   the xsi:null attribute appears if the class instance is set to 
   a null reference. */

[XmlRootAttribute("PurchaseOrder",Namespace="http://www.cpandl.com",
IsNullable=false)]
public ref class PurchaseOrder
{
public:
   Address^ ShipTo;
   String^ OrderDate;

   /* The XmlArrayAttribute changes the XML element name
       from the default of "OrderedItems" to "Items". */

   [XmlArrayAttribute("Items")]
   array<OrderedItem^>^OrderedItems;
   Decimal SubTotal;
   Decimal ShipCost;
   Decimal TotalCost;
};

public ref class Address
{
public:

   /* The XmlAttribute instructs the XmlSerializer to serialize the Name
         field as an XML attribute instead of an XML element (the default
         behavior). */

   [XmlAttributeAttribute]
   String^ Name;
   String^ Line1;

   /* Setting the IsNullable property to false instructs the 
         XmlSerializer that the XML attribute will not appear if 
         the City field is set to a null reference. */

   [XmlElementAttribute(IsNullable=false)]
   String^ City;
   String^ State;
   String^ Zip;
};

public ref class OrderedItem
{
public:
   String^ ItemName;
   String^ Description;
   Decimal UnitPrice;
   int Quantity;
   Decimal LineTotal;

   /* Calculate is a custom method that calculates the price per item,
         and stores the value in a field. */
   void Calculate()
   {
      LineTotal = UnitPrice * Quantity;
   }

};

public ref class Test
{
public:
   static void main()
   {
      // Read and write purchase orders.
      Test^ t = gcnew Test;
      t->CreatePO( "po.xml" );
      t->ReadPO( "po.xml" );
   }

private:
   void CreatePO( String^ filename )
   {
      // Create an instance of the XmlSerializer class;
      // specify the type of object to serialize.
      XmlSerializer^ serializer = gcnew XmlSerializer( PurchaseOrder::typeid );
      TextWriter^ writer = gcnew StreamWriter( filename );
      PurchaseOrder^ po = gcnew PurchaseOrder;

      // Create an address to ship and bill to.
      Address^ billAddress = gcnew Address;
      billAddress->Name = "Teresa Atkinson";
      billAddress->Line1 = "1 Main St.";
      billAddress->City = "AnyTown";
      billAddress->State = "WA";
      billAddress->Zip = "00000";

      // Set ShipTo and BillTo to the same addressee.
      po->ShipTo = billAddress;
      po->OrderDate = System::DateTime::Now.ToLongDateString();

      // Create an OrderedItem object.
      OrderedItem^ i1 = gcnew OrderedItem;
      i1->ItemName = "Widget S";
      i1->Description = "Small widget";
      i1->UnitPrice = (Decimal)5.23;
      i1->Quantity = 3;
      i1->Calculate();

      // Insert the item into the array.
      array<OrderedItem^>^items = {i1};
      po->OrderedItems = items;

      // Calculate the total cost.
      Decimal subTotal = Decimal(0);
      System::Collections::IEnumerator^ myEnum = items->GetEnumerator();
      while ( myEnum->MoveNext() )
      {
         OrderedItem^ oi = safe_cast<OrderedItem^>(myEnum->Current);
         subTotal = subTotal + oi->LineTotal;
      }

      po->SubTotal = subTotal;
      po->ShipCost = (Decimal)12.51;
      po->TotalCost = po->SubTotal + po->ShipCost;

      // Serialize the purchase order, and close the TextWriter.
      serializer->Serialize( writer, po );
      writer->Close();
   }

protected:
   void ReadPO( String^ filename )
   {
      // Create an instance of the XmlSerializer class;
      // specify the type of object to be deserialized.
      XmlSerializer^ serializer = gcnew XmlSerializer( PurchaseOrder::typeid );

      /* If the XML document has been altered with unknown 
            nodes or attributes, handle them with the 
            UnknownNode and UnknownAttribute events.*/
      serializer->UnknownNode += gcnew XmlNodeEventHandler( this, &Test::serializer_UnknownNode );
      serializer->UnknownAttribute += gcnew XmlAttributeEventHandler( this, &Test::serializer_UnknownAttribute );

      // A FileStream is needed to read the XML document.
      FileStream^ fs = gcnew FileStream( filename,FileMode::Open );

      // Declare an object variable of the type to be deserialized.
      PurchaseOrder^ po;

      /* Use the Deserialize method to restore the object's state with
            data from the XML document. */
      po = dynamic_cast<PurchaseOrder^>(serializer->Deserialize( fs ));

      // Read the order date.
      Console::WriteLine( "OrderDate: {0}", po->OrderDate );

      // Read the shipping address.
      Address^ shipTo = po->ShipTo;
      ReadAddress( shipTo, "Ship To:" );

      // Read the list of ordered items.
      array<OrderedItem^>^items = po->OrderedItems;
      Console::WriteLine( "Items to be shipped:" );
      System::Collections::IEnumerator^ myEnum1 = items->GetEnumerator();
      while ( myEnum1->MoveNext() )
      {
         OrderedItem^ oi = safe_cast<OrderedItem^>(myEnum1->Current);
         Console::WriteLine( "\t{0}\t{1}\t{2}\t{3}\t{4}", oi->ItemName, oi->Description, oi->UnitPrice, oi->Quantity, oi->LineTotal );
      }

      Console::WriteLine( "\t\t\t\t\t Subtotal\t{0}", po->SubTotal );
      Console::WriteLine( "\t\t\t\t\t Shipping\t{0}", po->ShipCost );
      Console::WriteLine( "\t\t\t\t\t Total\t\t{0}", po->TotalCost );
   }

   void ReadAddress( Address^ a, String^ label )
   {
      // Read the fields of the Address object.
      Console::WriteLine( label );
      Console::WriteLine( "\t{0}", a->Name );
      Console::WriteLine( "\t{0}", a->Line1 );
      Console::WriteLine( "\t{0}", a->City );
      Console::WriteLine( "\t{0}", a->State );
      Console::WriteLine( "\t{0}", a->Zip );
      Console::WriteLine();
   }

private:
   void serializer_UnknownNode( Object^ /*sender*/, XmlNodeEventArgs^ e )
   {
      Console::WriteLine( "Unknown Node:{0}\t{1}", e->Name, e->Text );
   }

   void serializer_UnknownAttribute( Object^ /*sender*/, XmlAttributeEventArgs^ e )
   {
      System::Xml::XmlAttribute^ attr = e->Attr;
      Console::WriteLine( "Unknown attribute {0}='{1}'", attr->Name, attr->Value );
   }
};

int main()
{
   Test::main();
}
using System;
using System.Xml;
using System.Xml.Serialization;
using System.IO;

/* The XmlRootAttribute allows you to set an alternate name
   (PurchaseOrder) of the XML element, the element namespace; by
   default, the XmlSerializer uses the class name. The attribute
   also allows you to set the XML namespace for the element.  Lastly,
   the attribute sets the IsNullable property, which specifies whether
   the xsi:null attribute appears if the class instance is set to
   a null reference. */
[XmlRootAttribute("PurchaseOrder", Namespace="http://www.cpandl.com",
IsNullable = false)]
public class PurchaseOrder
{
   public Address ShipTo;
   public string OrderDate;
   /* The XmlArrayAttribute changes the XML element name
    from the default of "OrderedItems" to "Items". */
   [XmlArrayAttribute("Items")]
   public OrderedItem[] OrderedItems;
   public decimal SubTotal;
   public decimal ShipCost;
   public decimal TotalCost;
}

public class Address
{
   /* The XmlAttribute instructs the XmlSerializer to serialize the Name
      field as an XML attribute instead of an XML element (the default
      behavior). */
   [XmlAttribute]
   public string Name;
   public string Line1;

   /* Setting the IsNullable property to false instructs the
      XmlSerializer that the XML attribute will not appear if
      the City field is set to a null reference. */
   [XmlElementAttribute(IsNullable = false)]
   public string City;
   public string State;
   public string Zip;
}

public class OrderedItem
{
   public string ItemName;
   public string Description;
   public decimal UnitPrice;
   public int Quantity;
   public decimal LineTotal;

   /* Calculate is a custom method that calculates the price per item,
      and stores the value in a field. */
   public void Calculate()
   {
      LineTotal = UnitPrice * Quantity;
   }
}

public class Test
{
   public static void Main()
   {
      // Read and write purchase orders.
      Test t = new Test();
      t.CreatePO("po.xml");
      t.ReadPO("po.xml");
   }

   private void CreatePO(string filename)
   {
      // Create an instance of the XmlSerializer class;
      // specify the type of object to serialize.
      XmlSerializer serializer =
      new XmlSerializer(typeof(PurchaseOrder));
      TextWriter writer = new StreamWriter(filename);
      PurchaseOrder po=new PurchaseOrder();

      // Create an address to ship and bill to.
      Address billAddress = new Address();
      billAddress.Name = "Teresa Atkinson";
      billAddress.Line1 = "1 Main St.";
      billAddress.City = "AnyTown";
      billAddress.State = "WA";
      billAddress.Zip = "00000";
      // Set ShipTo and BillTo to the same addressee.
      po.ShipTo = billAddress;
      po.OrderDate = System.DateTime.Now.ToLongDateString();

      // Create an OrderedItem object.
      OrderedItem i1 = new OrderedItem();
      i1.ItemName = "Widget S";
      i1.Description = "Small widget";
      i1.UnitPrice = (decimal) 5.23;
      i1.Quantity = 3;
      i1.Calculate();

      // Insert the item into the array.
      OrderedItem [] items = {i1};
      po.OrderedItems = items;
      // Calculate the total cost.
      decimal subTotal = new decimal();
      foreach(OrderedItem oi in items)
      {
         subTotal += oi.LineTotal;
      }
      po.SubTotal = subTotal;
      po.ShipCost = (decimal) 12.51;
      po.TotalCost = po.SubTotal + po.ShipCost;
      // Serialize the purchase order, and close the TextWriter.
      serializer.Serialize(writer, po);
      writer.Close();
   }

   protected void ReadPO(string filename)
   {
      // Create an instance of the XmlSerializer class;
      // specify the type of object to be deserialized.
      XmlSerializer serializer = new XmlSerializer(typeof(PurchaseOrder));
      /* If the XML document has been altered with unknown
      nodes or attributes, handle them with the
      UnknownNode and UnknownAttribute events.*/
      serializer.UnknownNode+= new
      XmlNodeEventHandler(serializer_UnknownNode);
      serializer.UnknownAttribute+= new
      XmlAttributeEventHandler(serializer_UnknownAttribute);

      // A FileStream is needed to read the XML document.
      FileStream fs = new FileStream(filename, FileMode.Open);
      // Declare an object variable of the type to be deserialized.
      PurchaseOrder po;
      /* Use the Deserialize method to restore the object's state with
      data from the XML document. */
      po = (PurchaseOrder) serializer.Deserialize(fs);
      // Read the order date.
      Console.WriteLine ("OrderDate: " + po.OrderDate);

      // Read the shipping address.
      Address shipTo = po.ShipTo;
      ReadAddress(shipTo, "Ship To:");
      // Read the list of ordered items.
      OrderedItem [] items = po.OrderedItems;
      Console.WriteLine("Items to be shipped:");
      foreach(OrderedItem oi in items)
      {
         Console.WriteLine("\t"+
         oi.ItemName + "\t" +
         oi.Description + "\t" +
         oi.UnitPrice + "\t" +
         oi.Quantity + "\t" +
         oi.LineTotal);
      }
      // Read the subtotal, shipping cost, and total cost.
      Console.WriteLine("\t\t\t\t\t Subtotal\t" + po.SubTotal);
      Console.WriteLine("\t\t\t\t\t Shipping\t" + po.ShipCost);
      Console.WriteLine("\t\t\t\t\t Total\t\t" + po.TotalCost);
   }

   protected void ReadAddress(Address a, string label)
   {
      // Read the fields of the Address object.
      Console.WriteLine(label);
      Console.WriteLine("\t"+ a.Name );
      Console.WriteLine("\t" + a.Line1);
      Console.WriteLine("\t" + a.City);
      Console.WriteLine("\t" + a.State);
      Console.WriteLine("\t" + a.Zip );
      Console.WriteLine();
   }

   private void serializer_UnknownNode
   (object sender, XmlNodeEventArgs e)
   {
      Console.WriteLine("Unknown Node:" +   e.Name + "\t" + e.Text);
   }

   private void serializer_UnknownAttribute
   (object sender, XmlAttributeEventArgs e)
   {
      System.Xml.XmlAttribute attr = e.Attr;
      Console.WriteLine("Unknown attribute " +
      attr.Name + "='" + attr.Value + "'");
   }
}
Imports System.Xml
Imports System.Xml.Serialization
Imports System.IO

' The XmlRootAttribute allows you to set an alternate name
' (PurchaseOrder) of the XML element, the element namespace; by
' default, the XmlSerializer uses the class name. The attribute
' also allows you to set the XML namespace for the element.  Lastly,
' the attribute sets the IsNullable property, which specifies whether
' the xsi:null attribute appears if the class instance is set to
' a null reference. 
<XmlRootAttribute("PurchaseOrder", _
 Namespace := "http://www.cpandl.com", IsNullable := False)> _
Public Class PurchaseOrder
    
    Public ShipTo As Address
    Public OrderDate As String
    ' The XmlArrayAttribute changes the XML element name
    ' from the default of "OrderedItems" to "Items". 
    <XmlArrayAttribute("Items")> _
    Public OrderedItems() As OrderedItem
    Public SubTotal As Decimal
    Public ShipCost As Decimal
    Public TotalCost As Decimal
End Class


Public Class Address
    ' The XmlAttribute instructs the XmlSerializer to serialize the Name
    ' field as an XML attribute instead of an XML element (the default
    ' behavior). 
    <XmlAttribute()> _
    Public Name As String
    Public Line1 As String
    
    ' Setting the IsNullable property to false instructs the
    ' XmlSerializer that the XML attribute will not appear if
    ' the City field is set to a null reference. 
    <XmlElementAttribute(IsNullable := False)> _
    Public City As String
    Public State As String
    Public Zip As String
End Class


Public Class OrderedItem
    Public ItemName As String
    Public Description As String
    Public UnitPrice As Decimal
    Public Quantity As Integer
    Public LineTotal As Decimal
    
    
    ' Calculate is a custom method that calculates the price per item,
    ' and stores the value in a field. 
    Public Sub Calculate()
        LineTotal = UnitPrice * Quantity
    End Sub
End Class


Public Class Test
    
   Public Shared Sub Main()
      ' Read and write purchase orders.
      Dim t As New Test()
      t.CreatePO("po.xml")
      t.ReadPO("po.xml")
   End Sub
    
   Private Sub CreatePO(filename As String)
      ' Create an instance of the XmlSerializer class;
      ' specify the type of object to serialize.
      Dim serializer As New XmlSerializer(GetType(PurchaseOrder))
      Dim writer As New StreamWriter(filename)
      Dim po As New PurchaseOrder()
        
      ' Create an address to ship and bill to.
      Dim billAddress As New Address()
      billAddress.Name = "Teresa Atkinson"
      billAddress.Line1 = "1 Main St."
      billAddress.City = "AnyTown"
      billAddress.State = "WA"
      billAddress.Zip = "00000"
      ' Set ShipTo and BillTo to the same addressee.
      po.ShipTo = billAddress
      po.OrderDate = System.DateTime.Now.ToLongDateString()
        
      ' Create an OrderedItem object.
      Dim i1 As New OrderedItem()
      i1.ItemName = "Widget S"
      i1.Description = "Small widget"
      i1.UnitPrice = CDec(5.23)
      i1.Quantity = 3
      i1.Calculate()
        
      ' Insert the item into the array.
      Dim items(0) As OrderedItem
      items(0) = i1
      po.OrderedItems = items
      ' Calculate the total cost.
      Dim subTotal As New Decimal()
      Dim oi As OrderedItem
      For Each oi In  items
         subTotal += oi.LineTotal
      Next oi
      po.SubTotal = subTotal
      po.ShipCost = CDec(12.51)
      po.TotalCost = po.SubTotal + po.ShipCost
      ' Serialize the purchase order, and close the TextWriter.
      serializer.Serialize(writer, po)
      writer.Close()
   End Sub
    
   Protected Sub ReadPO(filename As String)
      ' Create an instance of the XmlSerializer class;
      ' specify the type of object to be deserialized.
      Dim serializer As New XmlSerializer(GetType(PurchaseOrder))
      ' If the XML document has been altered with unknown
      ' nodes or attributes, handle them with the
      ' UnknownNode and UnknownAttribute events.
      AddHandler serializer.UnknownNode, AddressOf serializer_UnknownNode
      AddHandler serializer.UnknownAttribute, AddressOf serializer_UnknownAttribute
      
      ' A FileStream is needed to read the XML document.
      Dim fs As New FileStream(filename, FileMode.Open)
      ' Declare an object variable of the type to be deserialized.
      Dim po As PurchaseOrder
      ' Use the Deserialize method to restore the object's state with
      ' data from the XML document. 
      po = CType(serializer.Deserialize(fs), PurchaseOrder)
      ' Read the order date.
      Console.WriteLine(("OrderDate: " & po.OrderDate))
        
      ' Read the shipping address.
      Dim shipTo As Address = po.ShipTo
      ReadAddress(shipTo, "Ship To:")
      ' Read the list of ordered items.
      Dim items As OrderedItem() = po.OrderedItems
      Console.WriteLine("Items to be shipped:")
      Dim oi As OrderedItem
      For Each oi In  items
         Console.WriteLine((ControlChars.Tab & oi.ItemName & ControlChars.Tab & _
         oi.Description & ControlChars.Tab & oi.UnitPrice & ControlChars.Tab & _
         oi.Quantity & ControlChars.Tab & oi.LineTotal))
      Next oi
      ' Read the subtotal, shipping cost, and total cost.
      Console.WriteLine(( New String(ControlChars.Tab, 5) & _
      " Subtotal"  & ControlChars.Tab & po.SubTotal))
      Console.WriteLine(New String(ControlChars.Tab, 5) & _
      " Shipping" & ControlChars.Tab & po.ShipCost )
      Console.WriteLine( New String(ControlChars.Tab, 5) & _
      " Total" &  New String(ControlChars.Tab, 2) & po.TotalCost)
    End Sub
    
    Protected Sub ReadAddress(a As Address, label As String)
      ' Read the fields of the Address object.
      Console.WriteLine(label)
      Console.WriteLine(ControlChars.Tab & a.Name)
      Console.WriteLine(ControlChars.Tab & a.Line1)
      Console.WriteLine(ControlChars.Tab & a.City)
      Console.WriteLine(ControlChars.Tab & a.State)
      Console.WriteLine(ControlChars.Tab & a.Zip)
      Console.WriteLine()
    End Sub
        
    Private Sub serializer_UnknownNode(sender As Object, e As XmlNodeEventArgs)
        Console.WriteLine(("Unknown Node:" & e.Name & ControlChars.Tab & e.Text))
    End Sub
    
    
    Private Sub serializer_UnknownAttribute(sender As Object, e As XmlAttributeEventArgs)
        Dim attr As System.Xml.XmlAttribute = e.Attr
        Console.WriteLine(("Unknown attribute " & attr.Name & "='" & attr.Value & "'"))
    End Sub
End Class

備註

XML 序列化 (Serialization) 是將物件公用屬性和欄位轉換為儲存或傳輸所用的序列格式 (此處即為 XML) 的程。 還原序列化會從 XML 輸出重新建立其原始狀態的物件。 您可以將序列化視為將物件狀態儲存到資料流程或緩衝區的方式。 例如,ASP.NET 使用 XmlSerializer 類別來編碼 XML Web 服務訊息。

您物件中的資料是用程式語言來描述的,該程式語言會建構如類別、欄位、屬性、基本型別 (Primitive Type)、陣列,甚至是以 XmlElementXmlAttribute 物件為格式的內嵌 XML。 您可以選擇建立自己的類別、標注屬性,或使用 XML 架構定義工具 (Xsd.exe) ,根據現有的 XML 架構定義產生類別, (XSD) 檔。 如果您有 XML 架構,您可以執行 Xsd.exe,以產生一組強型別至架構的類別,並在序列化時加上屬性批註以遵守架構。

若要在物件與 XML 之間傳輸資料,需要從程式設計語言建構對應到 XML 架構,以及從 XML 架構對應到程式設計語言建構。 與 XmlSerializer Xsd.exe等相關工具可在設計階段和執行時間提供這兩種技術之間的橋樑。 在設計階段,使用 Xsd.exe 從自訂類別產生 XML 架構檔 (.xsd) ,或從指定的架構產生類別。 不論是哪一種情況,類別都以自訂屬性標注,以指示 XmlSerializer 如何在 XML 架構系統與 Common Language Runtime 之間對應。 在執行時間,類別的實例可以序列化為遵循指定架構的 XML 檔。 同樣地,這些 XML 檔也可以還原序列化為執行時間物件。 請注意,XML 架構是選擇性的,在設計階段或執行時間則不需要。

控制產生的 XML

若要控制產生的 XML,您可以將特殊屬性套用至類別和成員。 例如,若要指定不同的 XML 專案名稱,請將 套用 XmlElementAttribute 至公用欄位或屬性,並設定 ElementName 屬性。 如需類似屬性的完整清單,請參閱 控制 XML 序列化的屬性。 您也可以實作 IXmlSerializable 介面來控制 XML 輸出。

如果產生的 XML 必須符合萬維聯盟檔的第 5 節,則簡單物件存取通訊協定 (SOAP) 1.1,您必須使用 XmlTypeMapping 建構 XmlSerializer 。 若要進一步控制編碼的 SOAP XML,請使用 控制編碼 SOAP 序列化的屬性中列出的屬性

您可以使用 , XmlSerializer 利用強型別類別,而且仍具有 XML 的彈性。 使用 類型的 XmlElement 欄位或屬性, XmlAttribute 或在 XmlNode 強型別類別中,您可以直接將 XML 檔的元件讀入 XML 物件。

如果您使用可延伸的 XML 架構,您也可以使用 XmlAnyElementAttributeXmlAnyAttributeAttribute 屬性來序列化和還原序列化原始架構中找不到的專案或屬性。 若要使用 物件,請將 套用 XmlAnyElementAttribute 至傳回物件陣列的 XmlElement 欄位,或將 套用 XmlAnyAttributeAttribute 至傳回物件陣列的 XmlAttribute 欄位。

如果屬性或欄位傳回複雜物件 (例如陣列或類別執行個體),XmlSerializer 會將它轉換為主要 XML 文件中的巢狀項目。 例如,下列程式碼中的第一個類別會傳回第二個類別的實例。

Public Class MyClass  
    Public MyObjectProperty As MyObject  
End Class  

Public Class MyObject  
    Public ObjectName As String  
End Class  
public class MyClass  
{  
    public MyObject MyObjectProperty;  
}  
public class MyObject  
{  
    public string ObjectName;  
}  

序列化的 XML 輸出看起來像這樣:

<MyClass>  
  <MyObjectProperty>  
  <ObjectName>My String</ObjectName>  
  </MyObjectProperty>  
</MyClass>  

如果架構包含選擇性 (minOccurs = '0') 的專案,或架構包含預設值,則您有兩個選項。 其中一個選項是使用 System.ComponentModel.DefaultValueAttribute 來指定預設值,如下列程式碼所示。

Public Class PurchaseOrder  
    <System.ComponentModel.DefaultValueAttribute ("2002")> _  
    Public Year As String  
End Class  
public class PurchaseOrder  
{  
    [System.ComponentModel.DefaultValueAttribute ("2002")]  
    public string Year;  
}  

另一個選項是使用特殊模式來建立 所 XmlSerializer 辨識的布林值欄位,並將 套用 XmlIgnoreAttribute 至欄位。 模式是以 的形式 propertyNameSpecified 建立。 例如,如果有名為 「MyFirstName」 的欄位,您也會建立名為 「MyFirstNameSpecified」 的欄位,指示 XmlSerializer 是否要產生名為 「MyFirstName」 的 XML 元素。 下列範例會顯示這一點。

Public Class OptionalOrder  
    ' This field's value should not be serialized   
    ' if it is uninitialized.  
    Public FirstOrder As String  

    ' Use the XmlIgnoreAttribute to ignore the   
    ' special field named "FirstOrderSpecified".  
    <System.Xml.Serialization.XmlIgnoreAttribute> _  
    Public FirstOrderSpecified As Boolean  
End Class  
public class OptionalOrder  
{  
    // This field should not be serialized   
    // if it is uninitialized.  
    public string FirstOrder;  

    // Use the XmlIgnoreAttribute to ignore the   
    // special field named "FirstOrderSpecified".  
    [System.Xml.Serialization.XmlIgnoreAttribute]  
    public bool FirstOrderSpecified;  
}  

覆寫預設序列化

您也可以藉由建立其中一個適當的屬性,並將其新增至 類別的 XmlAttributes 實例,覆寫任何一組物件的序列化及其欄位和屬性。 以這種方式覆寫序列化有兩個用途:首先,即使您沒有來源的存取權,您也可以控制及增強 DLL 中找到的物件序列化;其次,您可以建立一組可序列化類別,但以多種方式序列化物件。 如需詳細資訊,請參閱 XmlAttributeOverrides 類別和 如何:控制衍生類別的序列化

若要序列化物件,請呼叫 Serialize 方法。 若要還原序列化物件,請呼叫 Deserialize 方法。

若要將 XML 命名空間新增至 XML 檔,請參閱 XmlSerializerNamespaces

注意

提供 XmlSerializer 實作 或 ICollectionIEnumerable 類別的特殊處理。 實作 IEnumerable 的類別必須實作只取單一參數的公用 Add 方法。 方法 Add 的參數的類型必須與 從 Current 所傳回值上的 屬性傳回 GetEnumerator 相同類型,或該型別的基底之一。 除了在 C# ) 中實作公用 Item 索引屬性 (索引子之外,實作 ICollection (的類別,例如 CollectionBase) IEnumerable ,而且必須具有整數類型的公用 Count 屬性。 方法的參數 Add 必須與 從 Item 屬性傳回的型別相同,或該型別的基底之一。 對於實作 ICollection 的類別,要序列化的值是從索引 Item 屬性擷取,而不是藉由呼叫 GetEnumerator

您必須具有寫入臨時目錄的許可權 (,如 TEMP 環境變數所定義,) 還原序列化物件。

動態產生的元件

為了提升效能,XML 序列化基礎結構會動態產生元件,以序列化和還原序列化指定的型別。 基礎結構會尋找並重複使用這些元件。 只有在使用下列建構函式時,才會發生此行為:

XmlSerializer.XmlSerializer(Type)

XmlSerializer.XmlSerializer(Type, String)

如果您使用任何其他建構函式,會產生多個相同元件的版本,且永遠不會卸載,這會導致記憶體流失和效能不佳。 最簡單的解決方案是使用先前提及的兩個建構函式之一。 否則,您必須快取 中的 Hashtable 元件,如下列範例所示。

Hashtable serializers = new Hashtable();  

// Use the constructor that takes a type and XmlRootAttribute.  
XmlSerializer s = new XmlSerializer(typeof(MyClass), myRoot);  

// Implement a method named GenerateKey that creates unique keys   
// for each instance of the XmlSerializer. The code should take   
// into account all parameters passed to the XmlSerializer   
// constructor.  
object key = GenerateKey(typeof(MyClass), myRoot);  

// Check the local cache for a matching serializer.  
XmlSerializer ser = (XmlSerializer)serializers[key];  
if (ser == null)   
{  
    ser = new XmlSerializer(typeof(MyClass), myRoot);  
    // Cache the serializer.  
    serializers[key] = ser;  
}

// Use the serializer to serialize or deserialize.
Dim serializers As New Hashtable()  

' Use the constructor that takes a type and XmlRootAttribute.  
Dim s As New XmlSerializer(GetType([MyClass]), myRoot)  

' Implement a method named GenerateKey that creates unique keys   
' for each instance of the XmlSerializer. The code should take   
' into account all parameters passed to the XmlSerializer   
' constructor.  
Dim key As Object = GenerateKey(GetType([MyClass]), myRoot)  

' Check the local cache for a matching serializer.  
Dim ser As XmlSerializer = CType(serializers(key), XmlSerializer)  

If ser Is Nothing Then  
    ser = New XmlSerializer(GetType([MyClass]), myRoot)  
    ' Cache the serializer.  
    serializers(key) = ser  
End If  

' Use the serializer to serialize or deserialize.

ArrayList 和泛型清單的序列化

XmlSerializer無法序列化或還原序列化下列專案:

不帶正負號 Long 列舉的序列化

XmlSerializer如果下列條件成立,則無法具現化來序列化列舉:列舉類型為 C#) 中不帶正負號的 long (ulong ,且列舉包含值大於 9,223,372,036,854,775,807 的任何成員。 例如,無法序列化下列專案。

public enum LargeNumbers: ulong  
{  
    a = 9223372036854775808  
}  
// At runtime, the following code will fail.  
xmlSerializer mySerializer=new XmlSerializer(typeof(LargeNumbers));  

標示為過時屬性的物件不再序列化

在 .NET Framework 3.5 中,類別 XmlSerializer 不再序列化標示為 [Obsolete] 的物件。

建構函式

XmlSerializer()

初始化 XmlSerializer 類別的新執行個體。

XmlSerializer(Type)

初始化 XmlSerializer 類別的新執行個體,該類別可將指定型別的物件序列化為 XML 文件,並可將 XML 文件還原序列化為指定型別的物件。

XmlSerializer(Type, String)

初始化 XmlSerializer 類別的新執行個體,該類別可將指定型別的物件序列化為 XML 文件,並可將 XML 文件還原序列化為指定型別的物件。 指定所有 XML 項目的預設命名空間。

XmlSerializer(Type, Type[])

初始化 XmlSerializer 類別的新執行個體,該類別可將指定型別的物件序列化為 XML 文件,並可將 XML 文件還原序列化為指定型別的物件。 如果屬性或欄位傳回陣列,extraTypes 參數就會指定可插入陣列的物件。

XmlSerializer(Type, XmlAttributeOverrides)

初始化 XmlSerializer 類別的新執行個體,該類別可將指定型別的物件序列化為 XML 文件,並可將 XML 文件還原序列化為指定型別的物件。 每個要序列化的物件本身會包含類別執行個體,這個多載可以其他類別覆寫。

XmlSerializer(Type, XmlAttributeOverrides, Type[], XmlRootAttribute, String)

初始化 XmlSerializer 類別的新執行個體,該類別可將 Object 型別的物件序列化為 XML 文件執行個體,並可將 XML 文件執行個體還原序列化為 Object 型別的物件。 每個要序列化的物件本身都可包含類別的執行個體,這個多載會使用其他類別對其進行覆寫。 這個多載也會指定所有 XML 項目的預設命名空間,以及要做為 XML 根項目的類別。

XmlSerializer(Type, XmlAttributeOverrides, Type[], XmlRootAttribute, String, String)

初始化 XmlSerializer 類別的新執行個體,該類別可將 Object 型別的物件序列化為 XML 文件執行個體,並可將 XML 文件執行個體還原序列化為 Object 型別的物件。 每個要序列化的物件本身都可包含類別的執行個體,這個多載會使用其他類別對其進行覆寫。 這個多載也會指定所有 XML 項目的預設命名空間,以及要做為 XML 根項目的類別。

XmlSerializer(Type, XmlAttributeOverrides, Type[], XmlRootAttribute, String, String, Evidence)
已過時。

初始化 XmlSerializer 類別的新執行個體,該類別可將指定型別的物件序列化為 XML 文件執行個體,並可將 XML 文件執行個體還原序列化為指定型別的物件。 這個多載可讓您提供序列化或還原序列化作業期間遇到的其他型別,以及所有 XML 項目的預設命名空間、用做 XML 根項目的類別及其位置,和存取所需的認證。

XmlSerializer(Type, XmlRootAttribute)

初始化 XmlSerializer 類別的新執行個體,該類別可將指定型別的物件序列化為 XML 文件,並可將 XML 文件還原序列化為指定型別的物件。 它還指定做為 XML 根項目的類別。

XmlSerializer(XmlTypeMapping)

使用將一個型別對應到另一個型別的物件,初始化 XmlSerializer 類別的執行個體。

方法

CanDeserialize(XmlReader)

取得值,指出這個 XmlSerializer 是否可以還原序列化指定的 XML 文件。

CreateReader()

傳回物件,該物件用於讀取要序列化的 XML 文件。

CreateWriter()

在衍生類別中覆寫時,傳回用於序列化物件的寫入器。

Deserialize(Stream)

還原序列化指定 Stream 所包含的 XML 文件。

Deserialize(TextReader)

還原序列化指定 TextReader 所包含的 XML 文件。

Deserialize(XmlReader)

還原序列化指定 XmlReader 所包含的 XML 文件。

Deserialize(XmlReader, String)

還原序列化指定 XmlReader 和編碼樣式所包含的 XML 文件。

Deserialize(XmlReader, String, XmlDeserializationEvents)

使用指定 XmlReader 包含的資料,還原序列化物件。

Deserialize(XmlReader, XmlDeserializationEvents)

還原序列化指定 XmlReader 包含的 XML 文件,並允許覆寫還原序列化期間發生的事件。

Deserialize(XmlSerializationReader)

還原序列化指定 XmlSerializationReader 所包含的 XML 文件。

Equals(Object)

判斷指定的物件是否等於目前的物件。

(繼承來源 Object)
FromMappings(XmlMapping[])

傳回建立自 XmlSerializer 物件陣列的 XmlTypeMapping 物件陣列。

FromMappings(XmlMapping[], Evidence)
已過時。

傳回 XmlSerializer 類別的執行個體,該執行個體建立自一個 XML 型別至另一個 XML 型別的對應。

FromMappings(XmlMapping[], Type)

傳回指定對應的 XmlSerializer 類別執行個體。

FromTypes(Type[])

傳回由型別陣列建立的 XmlSerializer 物件的陣列。

GenerateSerializer(Type[], XmlMapping[])

使用指定的對應傳回組件,該組件包含自訂序列化程式,用於序列化或還原序列化指定的型別。

GenerateSerializer(Type[], XmlMapping[], CompilerParameters)

使用指定的對應、編譯器設定和選項傳回組件,該組件包含自訂序列化程式,用於序列化或還原序列化指定的型別。

GetHashCode()

做為預設雜湊函式。

(繼承來源 Object)
GetType()

取得目前執行個體的 Type

(繼承來源 Object)
GetXmlSerializerAssemblyName(Type)

傳回組件名稱,該組件包含一個或多個 XmlSerializer 版本,是為序列化或還原序列化特定型別建立的。

GetXmlSerializerAssemblyName(Type, String)

傳回組件名稱,該組件包含指定命名空間中指定型別的序列化程式。

MemberwiseClone()

建立目前 Object 的淺層複製。

(繼承來源 Object)
Serialize(Object, XmlSerializationWriter)

序列化指定的 Object,並使用指定的 XmlSerializationWriter 將 XML 文件寫入檔案。

Serialize(Stream, Object)

序列化指定的 Object,並使用指定的 Stream 將 XML 文件寫入檔案。

Serialize(Stream, Object, XmlSerializerNamespaces)

序列化指定的 Object,並使用指定的 Stream 將 XML 文件寫入檔案,以參考指定的命名空間。

Serialize(TextWriter, Object)

序列化指定的 Object,並使用指定的 TextWriter 將 XML 文件寫入檔案。

Serialize(TextWriter, Object, XmlSerializerNamespaces)

將指定的 Object 序列化,使用指定的 TextWriter 將 XML 文件寫入檔案,並參考指定的命名空間。

Serialize(XmlWriter, Object)

序列化指定的 Object,並使用指定的 XmlWriter 將 XML 文件寫入檔案。

Serialize(XmlWriter, Object, XmlSerializerNamespaces)

將指定的 Object 序列化,使用指定的 XmlWriter 將 XML 文件寫入檔案,並參考指定的命名空間。

Serialize(XmlWriter, Object, XmlSerializerNamespaces, String)

序列化指定的物件,使用指定的 XmlWriter 將 XML 文件寫入檔案,並參考指定的命名空間和編碼樣式。

Serialize(XmlWriter, Object, XmlSerializerNamespaces, String, String)

序列化指定的 Object,並使用指定的 XmlWriter、XML 命名空間和編碼方式,將 XML 文件寫入檔案。

ToString()

傳回代表目前物件的字串。

(繼承來源 Object)

事件

UnknownAttribute

當還原序列化期間,XmlSerializer 遭遇未知型別的 XML 屬性時發生。

UnknownElement

當還原序列化期間,XmlSerializer 遭遇未知型別的 XML 項目時發生。

UnknownNode

當還原序列化期間,XmlSerializer 遭遇未知型別的 XML 節點時發生。

UnreferencedObject

在 SOAP 編碼的 XML 資料流還原序列化期間,XmlSerializer 遇到未使用 (未參考) 的可辨認型別時發生。

適用於

執行緒安全性

此型別具備執行緒安全。

另請參閱