C#2008与.NET 3.5 高级程序设计读书笔记(21) 对象序列化

1.对象序列化

术语序列化(serialization)描述了持久化(可能还包括传输)一个对象状态到流(如文件流,内存流)的过程.

当试图通过.NET远程处理层,XML Web服务或WCF这样的远程处理技术将一个对象复制到远程计算机时,具有对类型序列化的能力很关键.

虽然使用.NET序列化保存对象非常简单,但幕后的调用过程却非常复杂.例如,当一个对象被持久化到流时,所有的相关数据(基类,包含的对象等)也会被自动序列化.
2.为序列化配置对象

只需为每个类加上[Serializable]特性,如果要排除某些域,只需在前面加上[NonSerialized]

如: 

[Serializable]
public class Radio
{
  public bool hasTweeters;
  public bool hasSubWoofers;
  public double[] stationPresets;

  [NonSerialized]
   public string radioID = "XF-552RR6";
}

字段的类型对序列化的影响,如下

  [Serializable]
  public class Person
  {
      //公共字段
      public bool isAlive = true;
      //私有字段
      private int personAge = 21;
      //公共属性/私有数据
      private string fname = string.Empty;
      public string FristName
      {
          get { return fname; }
          set { fname = value; }
      }
  }

如果由BinaryFormatter或SoapFormatter处理,isAlive,personAge,fname都保存到了所选的流中,然而,XmlSerializer不会保存personAge的值.如果需要使用XmlSerializer序列化,就需要把字段定为公共的.

3.选择何种序列化

当使用BinaryFormatter 类型时,不仅仅是将对象中的字段数据持久化,而且也持久化每个类型的完全限定名称和定义程序集的完整名称(名称,版本,公钥标记,区域),在跨越.NET应用程序边界传递对象时,BinaryFormatter 成为理想的选择.

如果希望持久化的对象图被任意操作系统(Windows,Mac OS,Unix),任何应用程序框架(.NET,J2EE,COM)或编程语言使用,SoapFormatter,XmlSerializer是理想的选择.

 4.例子:

  [Serializable]
  public class Car
  {
    public Radio theRadio = new Radio();
    public bool isHatchBack;
  }

  [Serializable, XmlRoot(Namespace = "http://www.intertech.com")]
  public class JamesBondCar : Car
  {
    [XmlAttribute]
    public bool canFly;
    [XmlAttribute]
    public bool canSubmerge;

    public JamesBondCar(bool skyWorthy, bool seaWorthy)
    {
      canFly = skyWorthy;
      canSubmerge = seaWorthy;
    }
    // The XmlSerializer demands a default constructor!
    public JamesBondCar() { }
  }
  [Serializable]
  public class Radio
  {
    public bool hasTweeters;
    public bool hasSubWoofers;
    public double[] stationPresets;

    [NonSerialized]
    public string radioID = "XF-552RR6";
  }
  class Program
  {
    static void Main(string[] args)
    {
      Console.WriteLine("***** Fun with Object Serialization *****\n");

      // Make a JamesBondCar and set state.
      JamesBondCar jbc = new JamesBondCar();
      jbc.canFly = true;
      jbc.canSubmerge = false;
      jbc.theRadio.stationPresets = new double[] { 89.3, 105.1, 97.1 };
      jbc.theRadio.hasTweeters = true;

      // Now save / Load the car to a specific file.
      SaveAsBinaryFormat(jbc, "CarData.dat");
      LoadFromBinaryFile("CarData.dat");
      SaveAsSoapFormat(jbc, "CarData.soap");
      SaveAsXmlFormat(jbc, "CarData.xml");
      SaveListOfCars();
      SaveListOfCarsAsBinary();

      Console.ReadLine();
    }

    #region Save / Load as Binary Format
    static void SaveAsBinaryFormat(object objGraph, string fileName)
    {
      // Save object to a file named CarData.dat in binary.
      BinaryFormatter binFormat = new BinaryFormatter();

      using (Stream fStream = new FileStream(fileName,
            FileMode.Create, FileAccess.Write, FileShare.None))
      {
        binFormat.Serialize(fStream, objGraph);
      }
      Console.WriteLine("=> Saved car in binary format!");
    }

    static void LoadFromBinaryFile(string fileName)
    {
      BinaryFormatter binFormat = new BinaryFormatter();

      // Read the JamesBondCar from the binary file.
      using (Stream fStream = File.OpenRead(fileName))
      {
        JamesBondCar carFromDisk =
          (JamesBondCar)binFormat.Deserialize(fStream);
        Console.WriteLine("Can this car fly? : {0}", carFromDisk.canFly);
      }
    }
    #endregion

    #region Save as SOAP Format
    // Be sure to import System.Runtime.Serialization.Formatters.Soap 
    // and reference System.Runtime.Serialization.Formatters.Soap.dll.
    static void SaveAsSoapFormat(object objGraph, string fileName)
    {
      // Save object to a file named CarData.soap in SOAP format.
      SoapFormatter soapFormat = new SoapFormatter();

      using (Stream fStream = new FileStream(fileName,
        FileMode.Create, FileAccess.Write, FileShare.None))
      {
        soapFormat.Serialize(fStream, objGraph);
      }
      Console.WriteLine("=> Saved car in SOAP format!");
    }
    #endregion

    #region Save as XML Format
    static void SaveAsXmlFormat(object objGraph, string fileName)
    {
      // Save object to a file named CarData.xml in XML format.
      XmlSerializer xmlFormat = new XmlSerializer(typeof(JamesBondCar),
        new Type[] { typeof(Radio), typeof(Car) });

      using (Stream fStream = new FileStream(fileName,
        FileMode.Create, FileAccess.Write, FileShare.None))
      {
        xmlFormat.Serialize(fStream, objGraph);
      }
      Console.WriteLine("=> Saved car in XML format!");
    }
    #endregion

    #region Save collection of cars
    static void SaveListOfCars()
    {
      // Now persist a List<> of JamesBondCars.
      List<JamesBondCar> myCars = new List<JamesBondCar>();
      myCars.Add(new JamesBondCar(true, true));
      myCars.Add(new JamesBondCar(true, false));
      myCars.Add(new JamesBondCar(false, true));
      myCars.Add(new JamesBondCar(false, false));

      using (Stream fStream = new FileStream("CarCollection.xml",
        FileMode.Create, FileAccess.Write, FileShare.None))
      {
        XmlSerializer xmlFormat = new XmlSerializer(typeof(List<JamesBondCar>),
          new Type[] { typeof(JamesBondCar), typeof(Car), typeof(Radio) });
        xmlFormat.Serialize(fStream, myCars);
      }
      Console.WriteLine("=> Saved list of cars!");
    }

    static void SaveListOfCarsAsBinary()
    {
      // Save ArrayList object (myCars) as binary.
      List<JamesBondCar> myCars = new List<JamesBondCar>();

      BinaryFormatter binFormat = new BinaryFormatter();
      using (Stream fStream = new FileStream("AllMyCars.dat",
        FileMode.Create, FileAccess.Write, FileShare.None))
      {
        binFormat.Serialize(fStream, myCars);
      }
      Console.WriteLine("=> Saved list of cars in binary!");
    }
    #endregion
  }