C＃Xml序列化和反序列化

Question

我试图序列化一个对象并将其保存到Sql server 2008 xml字段中。 我还有一些反序列化代码，可以重新保存对象。 我能够将对象序列化并保存到db中，但是会出现“Root element missing”异常。

[XmlRoot("Patient")]
public class PatientXml
{
    private AddressXml _address = null;
    private EmergencyContactXml _emergencyContact = null;
    private PersonalXml _personal = null;

    [XmlElement]
    public PersonalXml Personal
    {
        get { return _personal; }
        set { _personal = value; }
    }

    [XmlElement]
    public AddressXml Address
    {
        get { return _address; }
        set { _address = value; }
    }

    [XmlElement]
    public EmergencyContactXml EmergencyContact
    {
        get { return _emergencyContact; }
        set { _emergencyContact = value; }
    }

    public PatientXml(){}
    public PatientXml(Patient patient)
    {
        _address = new AddressXml(patient.Address);
        _emergencyContact = new EmergencyContactXml(patient.EmergencyInfo);
        _personal = new PersonalXml(patient);
    }
}

public class PersonalXml
{
    private string _firstName = string.Empty, _lastName = string.Empty, _dateOfBirth = string.Empty, _phone = string.Empty;

    [XmlAttribute]
    public string FirstName
    {
        get { return _firstName; }
        set { _firstName = value; }
    }

    [XmlAttribute]
    public string LastName
    {
        get { return _lastName; }
        set { _lastName = value; }
    }

    [XmlAttribute]
    public string DateOfBirth
    {
        get { return _dateOfBirth; }
        set { _dateOfBirth = value; }
    }

    [XmlAttribute]
    public string Phone
    {
        get { return _phone; }
        set { _phone = value; }
    }

    public PersonalXml(){}
    public PersonalXml(Patient patient)
    {
        _firstName = patient.FirstName;
        _lastName = patient.LastName;
        _dateOfBirth = patient.DateOfBirth.ToShortDateString();
        _phone = patient.Phone;
    }
}

public class AddressXml
{
    private string _address1 = string.Empty, _address2 = string.Empty, _city = string.Empty, _state = string.Empty, _zip = string.Empty;

    [XmlAttribute]
    public string Address1
    {
        get { return _address1; }
        set { _address1 = value; }
    }

    [XmlAttribute]
    public string Address2
    {
        get { return _address2; }
        set { _address2 = value; }
    }

    [XmlAttribute]
    public string City
    {
        get { return _city; }
        set { _city = value; }
    }

    [XmlAttribute]
    public string State
    {
        get { return _state; }
        set { _state = value; }
    }

    [XmlAttribute]
    public string Zip
    {
        get { return _zip; }
        set { _zip = value; }
    }

    public AddressXml(){}
    public AddressXml(Address address)
    {
        _address1 = address.Address1;
        _address2 = address.Address2;
        _city = address.City;
        _state = address.State;
        _zip = address.ZipCode;
    }
}

public class EmergencyContactXml
{
    private string _name = string.Empty, _phone = string.Empty, _relationship = string.Empty;

    [XmlAttribute]
    public string Name
    {
        get { return _name; }
        set { _name = value; }
    }

    [XmlAttribute]
    public string Phone
    {
        get { return _phone; }
        set { _phone = value; }
    }

    [XmlAttribute]
    public string Relationship
    {
        get { return _relationship; }
        set { _relationship = value; }
    }

    public EmergencyContactXml(){}
    public EmergencyContactXml(EmergencyContact contact)
    {
        _name = contact.ContactName;
        _phone = contact.Phone;
        _relationship = contact.Relationship;
    }
}

序列化的Xml输出：

<Patient 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:xsd="http://www.w3.org/2001/XMLSchema">
    <Personal FirstName="Test" LastName="User 1" DateOfBirth="3/13/1966" Phone="6304449866" />
    <Address Address1="123 Some St" City="Bartlett" State="CT" Zip="60111" />
    <EmergencyContact Name="Dr Chanduwarthana" Phone="6309769484" Relationship="Father" />
</Patient>

Serising和反序列化代码：

public static class XmlSerializer
{
    public static string Serialize<T>(T item)
    {
        MemoryStream memStream = new MemoryStream();
        using (XmlTextWriter textWriter = new XmlTextWriter(memStream, Encoding.Unicode))
        {
            System.Xml.Serialization.XmlSerializer serializer = new System.Xml.Serialization.XmlSerializer(typeof(T));
            serializer.Serialize(textWriter, item);

            memStream = textWriter.BaseStream as MemoryStream;
        }
        if (memStream != null)
            return Encoding.Unicode.GetString(memStream.ToArray());
        else
            return null;
    }

    public static T Deserialize<T>(string xmlString)
    {
        if (string.IsNullOrWhiteSpace(xmlString))
            return default(T);

        using (MemoryStream memStream = new MemoryStream())
        {
            using (XmlTextWriter textWriter = new XmlTextWriter(memStream, Encoding.Unicode))
            {
                memStream.Position = 0;
                System.Xml.Serialization.XmlSerializer serializer = new System.Xml.Serialization.XmlSerializer(typeof(T));
                return (T)serializer.Deserialize(memStream);
            }
        }
    }
}

Answer 1

在您的反序列化代码中，您正在创建一个MemoryStream和XmlTextWriter，但是您没有给它反序列化的字符串。

using (MemoryStream memStream = new MemoryStream())
{
    using (XmlTextWriter textWriter = new XmlTextWriter(memStream, Encoding.Unicode))
    {
        // Omitted
    }
}

您可以将字节传递给内存流，并完全取消XmlTextWriter。

using (MemoryStream memStream = new MemoryStream(Encoding.Unicode.GetBytes(xmlString)))
{
    System.Xml.Serialization.XmlSerializer serializer = new System.Xml.Serialization.XmlSerializer(typeof(T));
    return (T)serializer.Deserialize(memStream);
}

Answer 2

看起来你有一个序列化为XML的句柄，所以请听我的建议，将XML存储在字符串字段（varchar，nvarchar，text，ntext）中，而不是专门的字段。

如果你做那个小开关，你将准备好......不需要进一步修改。

XML字段需要经过验证，而且还有一些令人头疼的问题，如果您的应用程序只是该字段的生产者和使用者，那么您也可以采用该快捷方式。 SQL2008（甚至2005）足够强大，可以补偿编译xml字段时可能节省的资源。

但是，我会优化你的代码，看起来你写的代码比你不得不多。 例如，您不再需要创建私有字段来存储属性中的数据，例如：

public PersonalXml Personal
{
    get { return _personal; }
    set { _personal = value; }
}

如果你写它像下面会工作得很好：

    public PersonalXml Personal { get ; set ; }

你可以削减更多的脂肪......

Answer 3

我相信你需要添加XML头：

<?xml version="1.0" encoding="utf-8" ?>

您可以修改serialize方法以接受可能导致添加此参数的可选参数：

public static string Serialize<T>(T item, bool includeHeader = false)
{
    MemoryStream memStream = new MemoryStream();
    using (XmlTextWriter textWriter = new XmlTextWriter(memStream, Encoding.Unicode))
    {
        System.Xml.Serialization.XmlSerializer serializer = new System.Xml.Serialization.XmlSerializer(typeof(T));
        serializer.Serialize(textWriter, item);

        memStream = textWriter.BaseStream as MemoryStream;
    }
    if (memStream != null)
        if (includeHeader)
        {
            return @"<?xml version=""1.0"" encoding=""utf-8"" ?>" + Environment.NewLine + Encoding.Unicode.GetString(memStream.ToArray());
        }
        else
        {
            return Encoding.Unicode.GetString(memStream.ToArray());
        }
    else
        return null;
}