XML 串行化可以採用一種以上的形式，從簡單到複雜。 例如，您可以串行化只包含公用字段和屬性的類別，如 XML 串行化簡介所示。 下列程式代碼範例可解決各種進階案例，包括如何使用 XML 串行化來產生符合特定 XML 架構 （XSD） 檔的 XML 數據流。
串行化 DataSet
除了串行化公用類別的實例之外，您也可以串行化 的 DataSet實例，如下列程式代碼範例所示：
Private Sub SerializeDataSet(filename As String)
Dim ser As XmlSerializer = new XmlSerializer(GetType(DataSet))
' Creates a DataSet; adds a table, column, and ten rows.
Dim ds As DataSet = new DataSet("myDataSet")
Dim t As DataTable = new DataTable("table1")
Dim c As DataColumn = new DataColumn("thing")
t.Columns.Add(c)
ds.Tables.Add(t)
Dim r As DataRow
Dim i As Integer
for i = 0 to 10
r = t.NewRow()
r(0) = "Thing " & i
t.Rows.Add(r)
Next
Dim writer As TextWriter = new StreamWriter(filename)
ser.Serialize(writer, ds)
writer.Close()
End Sub
private void SerializeDataSet(string filename)
{
XmlSerializer ser = new XmlSerializer(typeof(DataSet));
// Creates a DataSet; adds a table, column, and ten rows.
DataSet ds = new DataSet("myDataSet");
DataTable t = new DataTable("table1");
DataColumn c = new DataColumn("thing");
t.Columns.Add(c);
ds.Tables.Add(t);
DataRow r;
for (int i = 0; i < 10; i++) {
r = t.NewRow();
r[0] = "Thing " + i;
t.Rows.Add(r);
}
TextWriter writer = new StreamWriter(filename);
ser.Serialize(writer, ds);
writer.Close();
}
串行化 XmlElement 和 XmlNode
您也可以序列化 XmlElement 或 XmlNode 類別的實體，如下例程式碼所示：
private Sub SerializeElement(filename As String)
Dim ser As XmlSerializer = new XmlSerializer(GetType(XmlElement))
Dim myElement As XmlElement = _
new XmlDocument().CreateElement("MyElement", "ns")
myElement.InnerText = "Hello World"
Dim writer As TextWriter = new StreamWriter(filename)
ser.Serialize(writer, myElement)
writer.Close()
End Sub
Private Sub SerializeNode(filename As String)
Dim ser As XmlSerializer = _
new XmlSerializer(GetType(XmlNode))
Dim myNode As XmlNode = new XmlDocument(). _
CreateNode(XmlNodeType.Element, "MyNode", "ns")
myNode.InnerText = "Hello Node"
Dim writer As TextWriter = new StreamWriter(filename)
ser.Serialize(writer, myNode)
writer.Close()
End Sub
private void SerializeElement(string filename)
{
XmlSerializer ser = new XmlSerializer(typeof(XmlElement));
XmlElement myElement = new XmlDocument().CreateElement("MyElement", "ns");
myElement.InnerText = "Hello World";
TextWriter writer = new StreamWriter(filename);
ser.Serialize(writer, myElement);
writer.Close();
}
private void SerializeNode(string filename)
{
XmlSerializer ser = new XmlSerializer(typeof(XmlNode));
XmlNode myNode = new XmlDocument().
CreateNode(XmlNodeType.Element, "MyNode", "ns");
myNode.InnerText = "Hello Node";
TextWriter writer = new StreamWriter(filename);
ser.Serialize(writer, myNode);
writer.Close();
}
串行化類別，其中包含傳回複雜物件的欄位
如果屬性或欄位傳回複雜物件（例如陣列或類別實例），XmlSerializer 會將它轉換成巢狀在主要 XML 檔中的元素。 例如，下列程式代碼範例中的第一個類別會傳回第二個類別的實例：
Public Class PurchaseOrder
Public MyAddress As Address
End Class
Public Class Address
Public FirstName As String
End Class
public class PurchaseOrder
{
public Address MyAddress;
}
public record Address
{
public string FirstName;
}
序列化的 XML 輸出看起來可能如下所示：
<PurchaseOrder>
<MyAddress>
<FirstName>George</FirstName>
</MyAddress>
</PurchaseOrder>
串行化一組物件的陣列
您也可以序列化傳回物件陣列的欄位，如下列程式碼範例所示：
Public Class PurchaseOrder
public ItemsOrders () As Item
End Class
Public Class Item
Public ItemID As String
Public ItemPrice As decimal
End Class
public class PurchaseOrder
{
public Item [] ItemsOrders;
}
public class Item
{
public string ItemID;
public decimal ItemPrice;
}
如果訂購了兩個項目，序列化類別實例可能會像下列程式碼一樣：
<PurchaseOrder xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<ItemsOrders>
<Item>
<ItemID>aaa111</ItemID>
<ItemPrice>34.22</ItemPrice>
</Item>
<Item>
<ItemID>bbb222</ItemID>
<ItemPrice>2.89</ItemPrice>
</Item>
</ItemsOrders>
</PurchaseOrder>
序列化實作 ICollection 介面的類別
您可以藉由實 ICollection 作 介面並使用 XmlSerializer 來串行化這些類別的實例，來建立自己的集合類別。
備註
當類別實作 ICollection 介面時，只會串行化 類別所包含的集合。 加入類別的任何公用屬性或字段都不會串行化。 若要串行化，類別必須包含 Add 方法和 Item 屬性 （C# 索引器）。
Imports System.Collections
Imports System.IO
Imports System.Xml.Serialization
Public Class Test
Shared Sub Main()
Dim t As Test= new Test()
t.SerializeCollection("coll.xml")
End Sub
Private Sub SerializeCollection(filename As String)
Dim Emps As Employees = new Employees()
' Note that only the collection is serialized -- not the
' CollectionName or any other public property of the class.
Emps.CollectionName = "Employees"
Dim John100 As Employee = new Employee("John", "100xxx")
Emps.Add(John100)
Dim x As XmlSerializer = new XmlSerializer(GetType(Employees))
Dim writer As TextWriter = new StreamWriter(filename)
x.Serialize(writer, Emps)
writer.Close()
End Sub
End Class
Public Class Employees
Implements ICollection
Public CollectionName As String
Private empArray As ArrayList = new ArrayList()
Public ReadOnly Default Overloads _
Property Item(index As Integer) As Employee
get
return CType (empArray(index), Employee)
End Get
End Property
Public Sub CopyTo(a As Array, index As Integer) _
Implements ICollection.CopyTo
empArray.CopyTo(a, index)
End Sub
Public ReadOnly Property Count () As integer Implements _
ICollection.Count
get
Count = empArray.Count
End Get
End Property
Public ReadOnly Property SyncRoot ()As Object _
Implements ICollection.SyncRoot
get
return me
End Get
End Property
Public ReadOnly Property IsSynchronized () As Boolean _
Implements ICollection.IsSynchronized
get
return false
End Get
End Property
Public Function GetEnumerator() As IEnumerator _
Implements IEnumerable.GetEnumerator
return empArray.GetEnumerator()
End Function
Public Function Add(newEmployee As Employee) As Integer
empArray.Add(newEmployee)
return empArray.Count
End Function
End Class
Public Class Employee
Public EmpName As String
Public EmpID As String
Public Sub New ()
End Sub
Public Sub New (newName As String , newID As String )
EmpName = newName
EmpID = newID
End Sub
End Class
using System;
using System.Collections;
using System.IO;
using System.Xml.Serialization;
public class Test
{
static void Main()
{
Test t = new Test();
t.SerializeCollection("coll.xml");
}
private void SerializeCollection(string filename)
{
Employees Emps = new Employees();
// Note that only the collection is serialized -- not the
// CollectionName or any other public property of the class.
Emps.CollectionName = "Employees";
Employee John100 = new Employee("John", "100xxx");
Emps.Add(John100);
XmlSerializer x = new XmlSerializer(typeof(Employees));
TextWriter writer = new StreamWriter(filename);
x.Serialize(writer, Emps);
}
}
public class Employees : ICollection
{
public string CollectionName;
private ArrayList empArray = new ArrayList();
public Employee this[int index] => (Employee) empArray[index];
public void CopyTo(Array a, int index)
{
empArray.CopyTo(a, index);
}
public int Count => empArray.Count;
public object SyncRoot => this;
public bool IsSynchronized => false;
public IEnumerator GetEnumerator() => empArray.GetEnumerator();
public void Add(Employee newEmployee)
{
empArray.Add(newEmployee);
}
}
public class Employee
{
public string EmpName;
public string EmpID;
public Employee() {}
public Employee(string empName, string empID)
{
EmpName = empName;
EmpID = empID;
}
}
採購單範例
您可以將下列範例程式代碼剪下並貼到文本檔中，並以.cs或.vb擴展名重新命名。 使用 C# 或 Visual Basic 編譯程式編譯檔案。 然後使用可執行檔的名稱來執行它。
這個範例使用簡單的案例來示範如何使用Serialize方法，建立物件實例並將其序列化為檔案流。 XML 數據流會儲存至檔案。 然後，相同的檔案會使用 Deserialize 方法，讀取並重新建構成原始對象的複本。
在此範例中，名為 PurchaseOrder 的類別會序列化，然後反序列化。 也會包含名為 Address 的第二個類別，因為名為 ShipTo 的公用字段必須設定為 Address。 同樣地，會包含 OrderedItem 類別，因為 OrderedItem 對象的陣列必須設定至 OrderedItems 欄位。 最後，名為 Test 的類別包含串行化和還原串行化類別的程序代碼。
方法 CreatePO 會 PurchaseOrder建立、 Address和 OrderedItem 類別物件，並設定公用域值。 方法也會建構用於序列化和反序列化的 XmlSerializer 類的實例。
備註
程式代碼會將將串行化的類別類型傳遞至建構函式。 程式代碼也會建立 FileStream ，用來將 XML 資料流寫入 XML 檔。
方法 ReadPo 稍微簡單一點。 它只會建立物件以便反序列化並讀取其值。 如同使用CreatePo方法，您必須先建立XmlSerializer，並將要還原的類別類型傳遞給建構函式。 此外，還需要一個FileStream來讀取 XML 文件。 若要還原串行化物件，請使用 Deserialize 作為自變數來呼叫 FileStream 方法。 反序列化的對象必須被轉換為類型為PurchaseOrder的物件變數。 然後，程式代碼會讀取已還原串行化 PurchaseOrder的值。
備註
您可以讀取已建立的 PO.xml 檔案，來查看實際的 XML 輸出。
Imports System.IO
Imports System.Xml
Imports System.Xml.Serialization
Imports Microsoft.VisualBasic
' The XmlRoot attribute allows you to set an alternate name
' (PurchaseOrder) for the XML element and its 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.
<XmlRoot("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".
<XmlArray("Items")> _
Public OrderedItems() As OrderedItem
Public SubTotal As Decimal
Public ShipCost As Decimal
Public TotalCost As Decimal
End Class
Public Class Address
' The XmlAttribute attribute instructs the XmlSerializer to serialize the
' Name field as an XML attribute instead of an XML element (XML element is
' 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.
<XmlElement(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)
' Creates an instance of the XmlSerializer class;
' specifies the type of object to serialize.
Dim serializer As New XmlSerializer(GetType(PurchaseOrder))
Dim writer As New StreamWriter(filename)
Dim po As New PurchaseOrder()
' Creates 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()
' Creates an OrderedItem.
Dim i1 As New OrderedItem()
i1.ItemName = "Widget S"
i1.Description = "Small widget"
i1.UnitPrice = CDec(5.23)
i1.Quantity = 3
i1.Calculate()
' Inserts the item into the array.
Dim items(0) As OrderedItem
items(0) = i1
po.OrderedItems = items
' Calculates 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
' Serializes the purchase order, and close the TextWriter.
serializer.Serialize(writer, po)
writer.Close()
End Sub
Protected Sub ReadPO(filename As String)
' Creates an instance of the XmlSerializer class;
' specifies 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, handles 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
' Uses the Deserialize method to restore the object's state
' with data from the XML document.
po = CType(serializer.Deserialize(fs), PurchaseOrder)
' Reads the order date.
Console.WriteLine(("OrderDate: " & po.OrderDate))
' Reads the shipping address.
Dim shipTo As Address = po.ShipTo
ReadAddress(shipTo, "Ship To:")
' Reads 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
' Reads the subtotal, shipping cost, and total cost.
Console.WriteLine((ControlChars.Cr & New String _
(ControlChars.Tab, 5) & _
" Subtotal" & ControlChars.Tab & po.SubTotal & ControlChars.Cr & _
New String(ControlChars.Tab, 5) & " Shipping" & ControlChars.Tab & _
po.ShipCost & ControlChars.Cr & New String(ControlChars.Tab, 5) & _
" Total" & New String(ControlChars.Tab, 2) & po.TotalCost))
End Sub
Protected Sub ReadAddress(a As Address, label As String)
' Reads the fields of the Address.
Console.WriteLine(label)
Console.Write((ControlChars.Tab & a.Name & ControlChars.Cr & _
ControlChars.Tab & a.Line1 & ControlChars.Cr & ControlChars.Tab & _
a.City & ControlChars.Tab & a.State & ControlChars.Cr & _
ControlChars.Tab & a.Zip & ControlChars.Cr))
End Sub
Protected Sub serializer_UnknownNode(sender As Object, e As _
XmlNodeEventArgs)
Console.WriteLine(("Unknown Node:" & e.Name & _
ControlChars.Tab & e.Text))
End Sub
Protected 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 'serializer_UnknownAttribute
End Class 'Test
using System;
using System.IO;
using System.Xml;
using System.Xml.Serialization;
// The XmlRoot attribute allows you to set an alternate name
// (PurchaseOrder) for the XML element and its 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.
[XmlRoot("PurchaseOrder", Namespace="http://www.cpandl.com",
IsNullable = false)]
public class PurchaseOrder
{
public Address ShipTo;
public string OrderDate;
// The XmlArray attribute changes the XML element name
// from the default of "OrderedItems" to "Items".
[XmlArray("Items")]
public OrderedItem[] OrderedItems;
public decimal SubTotal;
public decimal ShipCost;
public decimal TotalCost;
}
public class Address
{
// The XmlAttribute attribute instructs the XmlSerializer to serialize the
// Name field as an XML attribute instead of an XML element (XML element is
// 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.
[XmlElement(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)
{
// Creates an instance of the XmlSerializer class;
// specifies the type of object to serialize.
XmlSerializer serializer = new XmlSerializer(typeof(PurchaseOrder));
TextWriter writer = new StreamWriter(filename);
PurchaseOrder po =new PurchaseOrder();
// Creates 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";
// Sets ShipTo and BillTo to the same addressee.
po.ShipTo = billAddress;
po.OrderDate = System.DateTime.Now.ToLongDateString();
// Creates an OrderedItem.
OrderedItem i1 = new OrderedItem();
i1.ItemName = "Widget S";
i1.Description = "Small widget";
i1.UnitPrice = (decimal) 5.23;
i1.Quantity = 3;
i1.Calculate();
// Inserts 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;
// Serializes the purchase order, and closes the TextWriter.
serializer.Serialize(writer, po);
writer.Close();
}
protected void ReadPO(string filename)
{
// Creates an instance of the XmlSerializer class;
// specifies 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, handles 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);
// Declares an object variable of the type to be deserialized.
PurchaseOrder po;
// Uses the Deserialize method to restore the object's state
// with data from the XML document. */
po = (PurchaseOrder) serializer.Deserialize(fs);
// Reads the order date.
Console.WriteLine ("OrderDate: " + po.OrderDate);
// Reads the shipping address.
Address shipTo = po.ShipTo;
ReadAddress(shipTo, "Ship To:");
// Reads 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);
}
// Reads the subtotal, shipping cost, and total cost.
Console.WriteLine(
"\n\t\t\t\t\t Subtotal\t" + po.SubTotal +
"\n\t\t\t\t\t Shipping\t" + po.ShipCost +
"\n\t\t\t\t\t Total\t\t" + po.TotalCost
);
}
protected void ReadAddress(Address a, string label)
{
// Reads the fields of the Address.
Console.WriteLine(label);
Console.Write("\t"+
a.Name +"\n\t" +
a.Line1 +"\n\t" +
a.City +"\t" +
a.State +"\n\t" +
a.Zip +"\n");
}
protected void serializer_UnknownNode
(object sender, XmlNodeEventArgs e)
{
Console.WriteLine("Unknown Node:" + e.Name + "\t" + e.Text);
}
protected void serializer_UnknownAttribute
(object sender, XmlAttributeEventArgs e)
{
System.Xml.XmlAttribute attr = e.Attr;
Console.WriteLine("Unknown attribute " +
attr.Name + "='" + attr.Value + "'");
}
}
XML 輸出看起來可能像這樣：
<?xml version="1.0" encoding="utf-8"?>
<PurchaseOrder xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="http://www.cpandl.com">
<ShipTo Name="Teresa Atkinson">
<Line1>1 Main St.</Line1>
<City>AnyTown</City>
<State>WA</State>
<Zip>00000</Zip>
</ShipTo>
<OrderDate>Wednesday, June 27, 2001</OrderDate>
<Items>
<OrderedItem>
<ItemName>Widget S</ItemName>
<Description>Small widget</Description>
<UnitPrice>5.23</UnitPrice>
<Quantity>3</Quantity>
<LineTotal>15.69</LineTotal>
</OrderedItem>
</Items>
<SubTotal>15.69</SubTotal>
<ShipCost>12.51</ShipCost>
<TotalCost>28.2</TotalCost>
</PurchaseOrder>
