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php爱好者> php文档>XML序列化

XML序列化

时间：2010-09-28 来源：czyhsl

序列化是将对象转化成易于传输的形式的过程。例如：可以序列化对象，并使用HTTP通过Internet在客户端和服务器之间进行传输。另一方面，反序列化在流中重新构造对象。

XML序列化只将对象的公共字段和属性值序列化为XML流。它不能转换方法、索引器、私有字段或只读属性（只读集合除外）。若要序列化对象的所有公共和私有字段和属性，需要使用DataContractSerializer而不要使用XML序列化。

代码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Collections;
using System.Runtime.Serialization;
using System.Xml;
using System.IO;

namespace DataContractSerializerDemo
{
    [DataContract(Name = "Customer", Namespace = "http://www.contoso.com")]
    class Person
    {
        [DataMember()]
        public string FirstName;
        [DataMember]
        public string LastName;
        [DataMember()]
        public int ID;

        public Person(string newfName, string newlName, int newID)
        {
            FirstName = newfName;
            LastName = newlName;
            ID = newID;
        }

        private ExtensionDataObject extensionData_Value;
        public ExtensionDataObject ExtensionData
        {
            get
            {
                return extensionData_Value;
            }
            set
            {
                extensionData_Value = value;
            }
        }
    }

    class Test
    {
        private Test() { }

        static void Main(string[] args)
        {
            try
            {
                WriteObject("DataContractSerializerDemo.xml");
                ReadOjbect("DataContractSerializerDemo.xml");
            }
            catch (SerializationException serExc)
            {
                Console.WriteLine("Serialization Failed");
                Console.WriteLine(serExc.Message);
            }
            catch(Exception exc)
            {
                Console.WriteLine(
               "The serialization operation failed: {0} StackTrace: {1}",
               exc.Message, exc.StackTrace);
            }
            finally
            {
                Console.WriteLine("Press <Enter> to exit....");
                Console.ReadLine();
            }
        }

        public static void WriteObject(string fileName) 
        {
            Console.WriteLine("Creating a Person object and serializing it.");
            Person p1 = new Person("Zighetti", "Barbara", 101);
            FileStream write = new FileStream(fileName, FileMode.Create);
            DataContractSerializer ser = new DataContractSerializer(typeof(Person));
            ser.WriteObject(write, p1);
            write.Close();
        }

        public static void ReadOjbect(string fileName) 
        {
            Console.WriteLine("Deserializing an instance of the object.");
            FileStream fs = new FileStream(fileName, FileMode.Open);
            XmlDictionaryReader reader = 
                XmlDictionaryReader.CreateTextReader(fs, new XmlDictionaryReaderQuotas());
            DataContractSerializer ser = new DataContractSerializer(typeof(Person));
            Person deserializedPerson = (Person)ser.ReadObject(reader, true);
            reader.Close();
            fs.Close();
            Console.WriteLine(String.Format("{0} {1}, ID: {2}",
                deserializedPerson.FirstName, deserializedPerson.LastName,
                deserializedPerson.ID));
        } 
    }
}

这是DataContractSerializer的一个Demo，必须要在Person类上指定或实现一个数据协定，当用于类成员时，指定该成员是数据协定的一部分。

谈到XML序列化，就不得不提XmlSerializer类，它的主要用途就是将对象序列化到文档中和从XML文档中反序列化对象。XML可序列化的项包含以下：

1）公共类的读/写属性和字段

2）实现ICollection或IEnumerable的类

3）XmlElement对象

4）XmlNode对象

5）DataSet对象

序列化数据集

代码

using System.Text;
using System.Xml;
using System.IO;
using System.Xml.Serialization;
using System.Data;

namespace XmlSerializerDemo
{
    class Test
    {
        static void Main(string[] args)
        {
            SerializeDataSet(@"D:\Dataset.xml");
        }

        private static void SerializeDataSet(string filename)
        {
            XmlSerializer ser = new XmlSerializer(typeof(DataSet));

            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();
        }
    }
}

序列化XmlElement和XmlNode

代码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Xml;
using System.IO;
using System.Xml.Serialization;

namespace XmlSerializerDemo
{
    class Test
    {
        static void Main(string[] args)
        {
            SerializeElement(@"D:\Dataset.xml");
        }

        private static 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 static 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();
        }
    }
}

输出

<?xml version="1.0" encoding="utf-8"?>
<MyElement xmlns="ns">Hello World</MyElement>

序列化复杂对象

代码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Xml;
using System.IO;
using System.Xml.Serialization;

namespace XmlSerializerDemo
{
    class Test
    {
        static void Main(string[] args)
        {
            SerailizeClass(@"D:\SerialClass.xml");
        }

        private static void SerailizeClass(string filename)
        {
            XmlSerializer serializer =
                 new XmlSerializer(typeof(PurchaseOrder));
            TextWriter write = new StreamWriter(filename);
            PurchaseOrder po = new PurchaseOrder();
            Address addr = new Address();
            addr.FirstName = "Beijing";

            po.MyAddress = addr;
            serializer.Serialize(write, po);
            write.Close();
        }
    }

    public class PurchaseOrder 
    {
        public Address MyAddress;
    }

    public class Address
    {
        public string FirstName;
    }
}

输出

代码

<?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">
  <MyAddress>
    <FirstName>Beijing</FirstName>
  </MyAddress>
</PurchaseOrder>

序列化对象数组

代码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Xml;
using System.IO;
using System.Xml.Serialization;

namespace XmlSerializerDemo
{
    class Test
    {
        static void Main(string[] args)
        {
            SerializeClassArray(@"D:\Dataset.xml");
        }

        private static void SerializeClassArray(string filename)
        {
            XmlSerializer serializer =
               new XmlSerializer(typeof(PurchaseOrder));
            TextWriter write = new StreamWriter(filename);
            PurchaseOrder po = new PurchaseOrder();

            Item item = new Item();
            item.ItemID = "xz01";
            item.ItemPrice = (decimal)3.2;

            Item item1 = new Item();
            item1.ItemID = "xz02";
            item1.ItemPrice = (decimal)4.5;

            Item[] items = { item, item1};
            po.ItemsOrders = items;
            serializer.Serialize(write, po);
            write.Close();
        }
    }

    public class PurchaseOrder 
    {
        public Item[] ItemsOrders;
    }

    public class Item
    {
       public string ItemID;
       public decimal ItemPrice;
    }
}

输出

代码

<?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">
  <ItemsOrders>
    <Item>
      <ItemID>xz01</ItemID>
      <ItemPrice>3.2</ItemPrice>
    </Item>
    <Item>
      <ItemID>xz02</ItemID>
      <ItemPrice>4.5</ItemPrice>
    </Item>
  </ItemsOrders>
</PurchaseOrder>

序列化实现ICollection的类

代码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Xml;
using System.IO;
using System.Xml.Serialization;
using System.Collections;
using System.Xml;

namespace XmlSerializerDemo
{
    class Test
    {
        static void Main(string[] args)
        {
            SerializeCollection(@"D:\SerialCollection.xml");
        }

        private static void SerializeCollection(string filename) 
        {
            Employees Emps = new Employees();
            Emps.CollectionName = "Employees";
            Employee emp = new Employee("Yao", "1111");
            Emps.Add(emp);

            XmlSerializer serializer = new XmlSerializer(typeof(Employees));
            TextWriter write = new StreamWriter(filename);
            serializer.Serialize(write, Emps);
            write.Close();
        }
    }

    public class Employee
    {
        public string EmpName;
        public string EmpID;

        public Employee() { }

        public Employee(string empName, string empID) 
        {
            EmpName = empName;
            EmpID = empID;
        }
    }

    public class Employees : ICollection 
    {
        public string CollectionName;
        public ArrayList empArray = new ArrayList();

        public Employee this[int index]
        {
            get { return (Employee)empArray[index]; }
        }

        #region ICollection 成员

        public void CopyTo(Array array, int index)
        {
            empArray.CopyTo(array, index);
        }

        public int Count
        {
            get { return empArray.Count; }
        }

        public bool IsSynchronized
        {
            get { return false; }
        }

        public object SyncRoot
        {
            get { return this; }
        }

        #endregion

        #region IEnumerable 成员

        public IEnumerator GetEnumerator()
        {
            return empArray.GetEnumerator();
        }

        #endregion

        public void Add(Employee newEmployee) 
        {
            empArray.Add(newEmployee);
        }
    }
}

输出

代码

<?xml version="1.0" encoding="utf-8"?>
<ArrayOfEmployee xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Employee>
    <EmpName>Yao</EmpName>
    <EmpID>1111</EmpID>
  </Employee>
</ArrayOfEmployee>

下面这是一个综合到前面所讲到所有的序列化的示例

代码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Xml;
using System.IO;
using System.Xml.Serialization;
using System.Collections;
using System.Xml;

namespace XmlSerializerDemo
{
    class Test
    {
        static void Main(string[] args)
        {
            Test t = new Test();
            t.CreatePO("po.xml");
            t.ReadPO("po.xml");
        }

        private void CreatePO(string filename)
        {
            XmlSerializer serializer =
                new XmlSerializer(typeof(PurchaseOrder));
            TextWriter write = new StreamWriter(filename);
            PurchaseOrder po = new PurchaseOrder();

            Address address = new Address();
            address.Name = "Teresa Atkinson";
            address.Line1 = "1 Main St.";
            address.City = "AnyTown";
            address.State = "WA";
            address.Zip = "00000";

            po.ShipTo = address;
            po.OrderDate = DateTime.Now.ToLongDateString();

            OrderItem ol = new OrderItem();
            ol.ItemName = "Widget S";
            ol.Description = "Small widget";
            ol.UnitPrice = (decimal)5.23;
            ol.Quantity = 3;
            ol.Calculate();

            OrderItem[] items = { ol };
            po.OrderItems = items;
            decimal subTotal = new decimal();
            foreach (OrderItem oi in items)
            {
                subTotal += oi.LineTotal;
            }
            po.SubTotal = subTotal;
            po.ShipCost = (decimal)12.51;
            po.TotalCost = po.SubTotal + po.ShipCost;
            serializer.Serialize(write, po);
            write.Close();
        }

        protected void ReadPO(string filename)
        {
            XmlSerializer serializer =
              new XmlSerializer(typeof(PurchaseOrder));
            serializer.UnknownNode += new
                XmlNodeEventHandler(serializer_UnknownNode);
            serializer.UnknownAttribute += new
                XmlAttributeEventHandler(serializer_UnknownAttribute);
            FileStream fs = new FileStream(filename, FileMode.Open);
            PurchaseOrder po;
            po = (PurchaseOrder)serializer.Deserialize(fs);
            Console.WriteLine("OrderDate: " + po.OrderDate);

            Address shipTo = po.ShipTo;
            ReadAddress(shipTo, "Ship To:");
            OrderItem[] items = po.OrderItems;
            Console.WriteLine("Items to be shipped:");
            foreach (OrderItem oi in items)
            {
                Console.WriteLine("\t" +
                   oi.ItemName + "\t" +
                oi.Description + "\t" +
                oi.UnitPrice + "\t" +
                oi.Quantity + "\t" +
                oi.LineTotal);
            }
            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)
        {
            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)
        {
            XmlAttribute attr = e.Attr;
            Console.WriteLine("Unknown attribute " +
                     attr.Name + "='" + attr.Value + "'");
        }
    }

   [XmlRootAttribute("PurchaseOrder",
    IsNullable = false)]
    public class PurchaseOrder
    {
        public Address ShipTo;
        public string OrderDate;

        [XmlArrayAttribute("Items")]
        public OrderItem[] OrderItems;
        public decimal SubTotal;
        public decimal ShipCost;
        public decimal TotalCost;
    }

    public class Address 
    {
        [XmlAttribute]
        public string Name;
        public string Line1;

        [XmlElementAttribute(IsNullable = false)]
        public string City;
        public string State;
        public string Zip;
    }

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

        public void Calculate()
        {
            LineTotal = UnitPrice * Quantity;
        }
    }
}

最后附带上使用XmlSerializer类时，应该注意的一些事项：

1）序列化数据只包含数据本身和类的结构。类型标识和程序集信息不包括在内。

2）只能序列化公共属性和字段。属性必须具有公共访问器（get和set方法）。如果必须序列化非公共数据，使用DataContractSerializer类而不使用XML序列化。

3）类必须具有默认的构造函数才能被XmlSerailizer序列化。

4）方法不能被序列化。

5）如果可实现 IEnumerable 或 ICollection 的类满足特定要求。实现 IEnumerable 的类必须实现采用单个参数的公共 Add 方法。Add 方法的参数必须与从 IEnumerator.Current 属性返回的类型一致（多态），该属性是从 GetEnumerator 方法返回的。实现 ICollection（如 CollectionBase）的类还必须有一个采用整数的公共 Item 索引属性（在 C# 中为索引器），而且必须有一个 integer 类型的公共 Count 属性。传递给 Add 方法的参数的类型必须与从 Item 属性返回的类型相同，或者为此类型的基之一。