Remoting中数据序列化

数据移动，序列化

      该文讲述通过网络传输序列化数据的两个类，BinaryFormatter和SoapFormatter类。这些类可以将类的实例转化成字节流通过网络传输到远程系统，也可以转换回原来的数据。

一、     使用序列化类

序列化一个类，并通过网络传输需要三步：

1、将要序列化的类创建成一个library对象。

2、编写一个发送程序来创建要序列化类的实例，并发送。

3、编写一个接收程序从流中读取数据，并重新创建原来的序列化类。

①  编写要序列化的类

每个要通过网络传输数据的类必须在原代码文件里使用[Serializable]标签。这表明，类中所有的数据在传输时都将要被序列化。下面展示了如何创建一个可以序列化的类。

using System;

[Serializable]

public class SerialEmployee

{

  public int EmployeeID

  public string LastName;

  public string FirstName;

  public int YearsService;

  public double Salary;

  public SerialEmployee()

  {

   EmployeeID = 0;

   LastName = null;

   FirstName = null;

   YearsService = 0;

   Salary = 0.0;

  }

}

为了使用该类来传输数据，必须现创建一个library文件：

csc /t:library SerialEmployee.cs

②  编写一个传输程序

创建数据类以后，可以创建一个程序来传输数据。可以使用BinaryFormatter和SoapFormatter类来序列化数据。

BinaryFormatter将数据序列化为二进制流。通常在实际数据中，增加一些信息，例如类名和版本号信息。

也可以使用SoapFormatter类使用XML格式来传输数据。使用XML的好处就是可以在任何系统和程序间传递数据。

   第一必须创建一个流的实例来传递数据。可以是任何类型的流，包括FileStream，MemoryStream，NetworkStream。然后，可以创建一个序列化类，使用Serialize()方法来通过流对象传递数据：

Stream str = new FileStream(  "testfile.bin", FileMode.Create, FileAccess.ReadWrite);

IFormatter formatter = new BinaryFormatter();

formatter.Serialize(str, data);

Iformatter类创建了一个用来序列化的类的实例(BinaryFormatter或者SoapFormatter)，使用Serialize()类来将数据序列化

using System;

using System.IO;

using System.Runtime.Serialization;

using System.Runtime.Serialization.Formatters.Soap;

class SoapTest

{

  public static void Main()

  {

   SerialEmployee emp1 = new SerialEmployee();

   SerialEmployee emp2 = new SerialEmployee();

   emp1.EmployeeID = 1;

   emp1.LastName = "Blum";

   emp1.FirstName = "Katie Jane";

   emp1.YearsService = 12;

   emp1.Salary = 35000.50;

   emp2.EmployeeID = 2;

   emp2.LastName = "Blum";

   emp2.FirstName = "Jessica";

   emp2.YearsService = 9;

   emp2.Salary = 23700.30;

   Stream str = new FileStream("soaptest.xml", FileMode.Create,

    FileAccess.ReadWrite);

   IFormatter formatter = new SoapFormatter();

   formatter.Serialize(str, emp1);

   formatter.Serialize(str, emp2);

   str.Close();

  }

}

      SoapFormatter类包含在System.Runtime.Serialization.Formatters.Soap命名空间，BinaryFormatter类包含在System.Runtime.Serialization.Formatters.Binary命名空间，Iformatter接口包含在System.Runtime.Serialization命名空间。

编译代码：CSC /r:SerialEmployee.dll SoapTest.cs

运行SoapTest.exe程序后，可以查看产生的soaptest.xml文件

<SOAP-ENV:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" Â

xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:SOAP-ENC= Â

"http://schemas.xmlsoap.org/soap/encoding/" xmlns:SOAP-ENV= Â

"http://schemas.xmlsoap.org/soap/envelope/" xmlns:clr= Â

"http://schemas.microsoft.com/soap/encoding/clr/1.0" SOAP-ENV:encodingStyle= Â

"http://schemas.xmlsoap.org/soap/encoding/">

<SOAP-ENV:Body>

<a1:SerialEmployee id="ref-1" xmlns:a1= Â

"http://schemas.microsoft.com/clr/assem/SerialEmployee%2C%20Version%3D0.Â

0.0.0%2C%20Culture%3Dneutral%2C%20PublicKeyToken%3Dnull">

<EmployeeID>1</EmployeeID>

<LastName id="ref-3">Blum</LastName>

<FirstName id="ref-4">Katie Jane</FirstName>

<YearsService>12</YearsService>

<Salary>35000.5</Salary>

</a1:SerialEmployee>

</SOAP-ENV:Body>

</SOAP-ENV:Envelope>

<SOAP-ENV:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" Â

xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:SOAP-ENC= Â

"http://schemas.xmlsoap.org/soap/encoding/" xmlns:SOAP-ENV= Â

"http://schemas.xmlsoap.org/soap/envelope/" xmlns:clr= Â

"http://schemas.microsoft.com/soap/encoding/clr/1.0" SOAP-ENV:encodingStyle= Â

"http://schemas.xmlsoap.org/soap/encoding/">

<SOAP-ENV:Body>

<a1:SerialEmployee id="ref-1" xmlns:a1= Â

"http://schemas.microsoft.com/clr/assem/SerialEmployee%2C%20Version%3D0.Â

0.0.0%2C%20Culture%3Dneutral%2C%20PublicKeyToken%3Dnull">

<EmployeeID>2</EmployeeID>

<LastName id="ref-3">Blum</LastName>

<FirstName id="ref-4">Jessica</FirstName>

<YearsService>9</YearsService>

<Salary>23700.3</Salary>

</a1:SerialEmployee>

</SOAP-ENV:Body>

</SOAP-ENV:Envelope>

       查看soaptest.xml文件，我们可以发现在序列化类中SOAP是如何定义每个数据元素。一个值得注意的重要XML数据特点如下：

<a1:SerialEmployee id="ref-1" xmlns:a1= Â

"http://schemas.microsoft.com/clr/assem/SerialEmployee%2C%20Version%3D0.Â0.0.0.%2C%20Culture%3Dneutral%2C%20PublicKeyToken%3Dnull">

      这里，XML中定义的数据使用了序列化数据类的实际类名。如果接收程序使用了另一个不同的类名，会和从流中读取的XML数据不匹配。类不匹配，读取将会失败。

      下面的代码展示了如何序列化数据，将数据传送到远程系统。

using System;

using System.Net;

using System.Net.Sockets;

using System.Runtime.Serialization;

using System.Runtime.Serialization.Formatters.Binary;

class BinaryDataSender

{

  public static void Main()

  {

   SerialEmployee emp1 = new SerialEmployee();

   SerialEmployee emp2 = new SerialEmployee();

   emp1.EmployeeID = 1;

   emp1.LastName = "Blum";

   emp1.FirstName = "Katie Jane";

   emp1.YearsService = 12;

   emp1.Salary = 35000.50;

   emp2.EmployeeID = 2;

   emp2.LastName = "Blum";

   emp2.FirstName = "Jessica";

   emp2.YearsService = 9;

   emp2.Salary = 23700.30;

   TcpClient client = new TcpClient("127.0.0.1", 9050);

   IFormatter formatter = new BinaryFormatter();

   NetworkStream strm = client.GetStream();

   formatter.Serialize(strm, emp1);

   formatter.Serialize(strm, emp2);

   strm.Close();

   client.Close();

  }

}

因为BinaryFormatter和SoapFormatter类需要一个Stream对象来传递序列化的数据，所以要使用一个TCP Socket对象或者一个TcpClient对象来传递数据，不能直接使用UDP。

③编写一个接收程序

using System;

using System.Net;

using System.Net.Sockets;

using System.Runtime.Serialization;

using System.Runtime.Serialization.Formatters.Binary;

class BinaryDataRcvr

{

  public static void Main()

  {

   TcpListener server = new TcpListener(9050);

   server.Start();

   TcpClient client = server.AcceptTcpClient();

   NetworkStream strm = client.GetStream();

   IFormatter formatter = new BinaryFormatter();

   SerialEmployee emp1 = (SerialEmployee)formatter.Deserialize(strm);

  Console.WriteLine("emp1.EmployeeID = {0}", emp1.EmployeeID);

   Console.WriteLine("emp1.LastName = {0}", emp1.LastName);

   Console.WriteLine("emp1.FirstName = {0}", emp1.FirstName);

   Console.WriteLine("emp1.YearsService = {0}", emp1.YearsService);

   Console.WriteLine("emp1.Salary = {0}\n", emp1.Salary);

   SerialEmployee emp2 = (SerialEmployee)formatter.Deserialize(strm);

   Console.WriteLine("emp2.EmployeeID = {0}", emp2.EmployeeID);

   Console.WriteLine("emp2.LastName = {0}", emp2.LastName);

   Console.WriteLine("emp2.FirstName = {0}", emp2.FirstName);

   Console.WriteLine("emp2.YearsService = {0}", emp2.YearsService);

   Console.WriteLine("emp2.Salary = {0}", emp2.Salary);

   strm.Close();

   server.Stop();

  }

}

二、     程序改进

在前面的程序中有一个假设：发送者的所有数据都被接收者接收。如果数据丢失，调用Deserialize()方法会发生错误。一个简单的解决方法是将序列化数据放到MemoryStream对象中。MemoryStream对象将所有的序列化数据保存在内存中，可以很容易得到序列化数据的大小。当传递数据时，将数据大小和数据一起传递。

using System;

using System.IO;

using System.Net;

using System.Net.Sockets;

using System.Runtime.Serialization;

using System.Runtime.Serialization.Formatters.Soap;

class BetterDataSender

{

  public void SendData (NetworkStream strm, SerialEmployee emp)

  {

   IFormatter formatter = new SoapFormatter();

   MemoryStream memstrm = new MemoryStream();

   formatter.Serialize(memstrm, emp);

   byte[] data = memstrm.GetBuffer();

   int memsize = (int)memstrm.Length;

   byte[] size = BitConverter.GetBytes(memsize);

   strm.Write(size, 0, 4);

   strm.Write(data, 0, memsize);

   strm.Flush();

   memstrm.Close();

  }

  public BetterDataSender()

  {

   SerialEmployee emp1 = new SerialEmployee();

   SerialEmployee emp2 = new SerialEmployee();

   emp1.EmployeeID = 1;

   emp1.LastName = "Blum";

   emp1.FirstName = "Katie Jane";

   emp1.YearsService = 12;

   emp1.Salary = 35000.50;

   emp2.EmployeeID = 2;

   emp2.LastName = "Blum";

   emp2.FirstName = "Jessica";

   emp2.YearsService = 9;

   emp2.Salary = 23700.30;

   TcpClient client = new TcpClient("127.0.0.1", 9050);

   NetworkStream strm = client.GetStream();

   SendData(strm, emp1);

   SendData(strm, emp2);

   strm.Close();

   client.Close();

  }

  public static void Main()

  {

   BetterDataSender bds = new BetterDataSender();

  }

}

接收数据程序如下：

using System;

using System.IO;

using System.Net;

using System.Net.Sockets;

using System.Runtime.Serialization;

using System.Runtime.Serialization.Formatters.Soap;

class BetterDataRcvr

{

  private SerialEmployee RecvData (NetworkStream strm)

  {

   MemoryStream memstrm = new MemoryStream();

   byte[] data = new byte[4];

   int recv = strm.Read(data, 0, 4);

   int size = BitConverter.ToInt32(data, 0);

   int offset = 0;

   while(size > 0)

   {

     data = new byte[1024];

     recv = strm.Read(data, 0, size);

     memstrm.Write(data, offset, recv);

     offset += recv;

     size -= recv;

   }

   IFormatter formatter = new SoapFormatter();

   memstrm.Position = 0;

   SerialEmployee emp = (SerialEmployee)formatter.Deserialize(memstrm);

   memstrm.Close();

   return emp;

  }

  public BetterDataRcvr()

  {

   TcpListener server = new TcpListener(9050);

   server.Start();

   TcpClient client = server.AcceptTcpClient();

   NetworkStream strm = client.GetStream();

   SerialEmployee emp1 = RecvData(strm);

   Console.WriteLine("emp1.EmployeeID = {0}", emp1.EmployeeID);

   Console.WriteLine("emp1.LastName = {0}", emp1.LastName);

   Console.WriteLine("emp1.FirstName = {0}", emp1.FirstName);

   Console.WriteLine("emp1.YearsService = {0}", emp1.YearsService);

   Console.WriteLine("emp1.Salary = {0}\n", emp1.Salary);

   SerialEmployee emp2 = RecvData(strm);

   Console.WriteLine("emp2.EmployeeID = {0}", emp2.EmployeeID);

   Console.WriteLine("emp2.LastName = {0}", emp2.LastName);

   Console.WriteLine("emp2.FirstName = {0}", emp2.FirstName);

   Console.WriteLine("emp2.YearsService = {0}", emp2.YearsService);

   Console.WriteLine("emp2.Salary = {0}", emp2.Salary);

   strm.Close();

   server.Stop();

  }

  public static void Main()

  {

   BetterDataRcvr bdr = new BetterDataRcvr();

  }

}

 

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