ISerializable接口简析之二

上一篇"学习.NET(6) ISerializable接口简析"中已经分析过如何把Serializable的对象保存到MemoryStream中。通过BitFormatter可以很轻易的把MemoryStream保存为二进制数组中，无论是存为二进制文件，还是保存在数据库等可以存储数据的地方，以便将来可以轻易的Deserialize。当然二进制数据Byte[]总是不方便使用，可以UnicodeEncoding，BitConverter等辅助类可以很容易的把上述二进制数据转化为String，同样可以进行存储以便将来使用。

然而，除了上述方法之外，还有另外一种选择：保存数据到XML文件。

要指定一个Class可以被存储到XML文件，首先要为该Class应用DataContractAttribute。同时为需要保存的Field应用DataMemberAttribute。特别的是，为了Enum数据，可以应用EnumMemberAttribute属性。

以下为简单的测试代码(根据MSDN的示例代码修改而来)：

[DataContract]
internal enum DisplayLanguage
{
    [EnumMember(Value = "EN")]
    English = 0,
    [EnumMember(Value = "CN")]
    Chinese = 1,
}

[DataContract(Name = "Customer", Namespace = "http://www.google.com")]
class TESTData : IExtensibleDataObject
{
    private String strFirst = null;
    private Int32? nTest = null;

    [DataMember()]
    public string FirstName
    {
        get { return strFirst; }
        set { strFirst = value; }
    }
    [DataMember]
    public string LastName;
    [DataMember()]
    public int ID;
    [DataMember()]
    public DisplayLanguage CellDisplay;
    [DataMember()]
    public Int32? TestNumber
    {
        get { return nTest; }
        set { nTest = value; }
    }
    [DataMember()]
    public List<String> listValues = new List<string>();

    public TESTData(string newfName, string newLName, int newID, DisplayLanguage ds)
    {
        FirstName = newfName;
        LastName = newLName;
        ID = newID;
        CellDisplay = ds;
        nTest = null;
        listValues.Add("TEST");
        listValues.Add("Test2");
    }

    private ExtensionDataObject extensionData_Value;

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

以上代码中，我不仅使用了Enum数据，同时使用了Int32?即Nullable<Int32>类型；以及List<String>类型。

以下是测试代码：

public sealed class Test
{
    private Test() { }

    public static void Main()
    {
        try
        {
            WriteObject("DataContractSerializerExample.xml");
            ReadObject("DataContractSerializerExample.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.");
        TESTData p1 = new TESTData("Zighetti", "Barbara", 101, DisplayLanguage.Chinese);
        p1.FirstName = "Madrid";
        p1.TestNumber = 5;
        FileStream writer = new FileStream(fileName, FileMode.Create);
        DataContractSerializer ser =
            new DataContractSerializer(typeof(TESTData));
        ser.WriteObject(writer, p1);
        writer.Close();
    }

    public static void ReadObject(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(TESTData));

        // Deserialize the data and read it from the instance.
        TESTData deserializedPerson =
            (TESTData)ser.ReadObject(reader, true);
        reader.Close();
        fs.Close();
        Console.WriteLine(String.Format("{0} {1}, ID: {2}, Display: {3}, Test: {4}",
        deserializedPerson.FirstName, deserializedPerson.LastName,
        deserializedPerson.ID, deserializedPerson.CellDisplay, deserializedPerson.TestNumber == null? "NULL" : deserializedPerson.TestNumber.Value.ToString()));
    }

看看生成的XML文件：

<Customer xmlns="http://www.google.com" xmlns:i="http://www./2001/XMLSchema-instance"><CellDisplay>CN</CellDisplay><FirstName>Madrid</FirstName><ID>101</ID><LastName>Barbara</LastName><TestNumber>5</TestNumber><listValues xmlns:a="http://schemas.microsoft.com/2003/10/Serialization/Arrays"><a:string>TEST</a:string><a:string>Test2</a:string></listValues></Customer>