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C# Xml 序列化和反序列化

c#c#-4.0c#-3.0xml-serializationc#-2.0
11

我正试图将一个对象序列化并保存到 Sql server 2008 xml 字段中。我还有一些反序列化代码来重新生成该对象。我能够将对象序列化并保存到数据库中，但是遇到了“根元素丢失”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>

序列化和反序列化代码：
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);
            }
        }
    }
}
3个回答
11
在您的反序列化代码中，您创建了一个MemoryStream和XmlTextWriter，但没有提供要反序列化的字符串。
using (MemoryStream memStream = new MemoryStream())
{
    using (XmlTextWriter textWriter = new XmlTextWriter(memStream, Encoding.Unicode))
    {
        // Omitted
    }
}

你可以将字节传递给内存流，完全摆脱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);
}
1
成功了！只是好奇……TextWriter出了什么问题？ - Skadoosh
2
@KP。由于您没有构建任何XML，因此XmlTextWriter在反序列化中并不必要。在这种情况下，它是使用对MemoryStream的引用创建的，并被指示使用Unicode，但除了创建之外没有被引用。我还注意到序列化代码中的MemoryStream没有被处理。您应该考虑将其包装在using块中进行修订。 - Dave Fancher
1

看起来你已经掌握了将数据序列化为XML的方法，那么请听我的建议，将XML存储在字符串字段（varchar、nvarchar、text、ntext）中，而不是专门的字段。

如果你做出这个小改变，你就可以直接使用了...无需进一步修改。

XML字段需要进行验证，可能会带来很多麻烦。如果你的应用程序只是生产者和消费者，那么你最好采取这种捷径。SQL2008（甚至2005）足够强大，可以弥补编译xml字段所节省的资源。

然而，我建议你优化一下代码，看起来你写了比必要的代码还多。例如，你不再需要创建一个私有字段来存储属性中的数据，例如：

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

如果您编写的代码如下所示，它将正常工作：

    public PersonalXml Personal { get ; set ; }

你可以删掉更多的冗余代码...

我认为 SQL Server 2008 中的 XML 字段更适用于 XML 查询优化。但是我是否也可以使用其他字段，如 varchar、nvarchar 等？ - Skadoosh
0

我相信你需要添加XML头：

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

你可以修改你的序列化方法，接受一个可选参数，这将导致它被添加进去：
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;
}
我该怎么做？当我序列化对象时，XML代码就被生成了。 - Skadoosh
你应该能够将它添加到serialize方法的输出中。 - competent_tech
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