这里有一个关于如何做到这一点的很好的教程

基本上应该使用System.Xml.Serialization.XmlSerializer类来做到这一点。

可以将下面的函数复制到任何对象，以使用System.Xml名称空间添加XML保存函数。

/// <summary>
/// Saves to an xml file
/// </summary>
/// <param name="FileName">File path of the new xml file</param>
public void Save(string FileName)
{
    using (var writer = new System.IO.StreamWriter(FileName))
    {
        var serializer = new XmlSerializer(this.GetType());
        serializer.Serialize(writer, this);
        writer.Flush();
    }
}

要从保存的文件创建对象，添加以下函数并将[ObjectType]替换为要创建的对象类型。

/// <summary>
/// Load an object from an xml file
/// </summary>
/// <param name="FileName">Xml file name</param>
/// <returns>The object created from the xml file</returns>
public static [ObjectType] Load(string FileName)
{
    using (var stream = System.IO.File.OpenRead(FileName))
    {
        var serializer = new XmlSerializer(typeof([ObjectType]));
        return serializer.Deserialize(stream) as [ObjectType];
    }
}

我的工作代码。返回utf8 xml启用空命名空间。

// override StringWriter
public class Utf8StringWriter : StringWriter
{
    public override Encoding Encoding => Encoding.UTF8;
}

private string GenerateXmlResponse(Object obj)
{    
    Type t = obj.GetType();

    var xml = "";

    using (StringWriter sww = new Utf8StringWriter())
    {
        using (XmlWriter writer = XmlWriter.Create(sww))
        {
            var ns = new XmlSerializerNamespaces();
            // add empty namespace
            ns.Add("", "");
            XmlSerializer xsSubmit = new XmlSerializer(t);
            xsSubmit.Serialize(writer, obj, ns);
            xml = sww.ToString(); // Your XML
        }
    }
    return xml;
}

示例返回响应Yandex api支付Aviso url:

<?xml version="1.0" encoding="utf-8"?><paymentAvisoResponse xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" performedDatetime="2017-09-01T16:22:08.9747654+07:00" code="0" shopId="54321" invoiceId="12345" orderSumAmount="10643" />

必须使用XmlSerializer进行XML序列化。下面是一个示例代码片段。

 XmlSerializer xsSubmit = new XmlSerializer(typeof(MyObject));
 var subReq = new MyObject();
 var xml = "";

 using(var sww = new StringWriter())
 {
     using(XmlWriter writer = XmlWriter.Create(sww))
     {
         xsSubmit.Serialize(writer, subReq);
         xml = sww.ToString(); // Your XML
     }
 }

根据泛型类的@kiquenet请求:

public class MySerializer<T> where T : class
{
    public static string Serialize(T obj)
    {
        XmlSerializer xsSubmit = new XmlSerializer(typeof(T));
        using (var sww = new StringWriter())
        {
            using (XmlTextWriter writer = new XmlTextWriter(sww) { Formatting = Formatting.Indented })
            {
                xsSubmit.Serialize(writer, obj);
                return sww.ToString();
            }
        }
    }
}

用法:

string xmlMessage = MySerializer<MyClass>.Serialize(myObj);

您可以使用如下函数从任何对象获取序列化的XML。

public static bool Serialize<T>(T value, ref string serializeXml)
{
    if (value == null)
    {
        return false;
    }
    try
    {
        XmlSerializer xmlserializer = new XmlSerializer(typeof(T));
        StringWriter stringWriter = new StringWriter();
        XmlWriter writer = XmlWriter.Create(stringWriter);

        xmlserializer.Serialize(writer, value);

        serializeXml = stringWriter.ToString();

        writer.Close();
        return true;
    }
    catch (Exception ex)
    {
        return false;
    }
}

你可以从客户端调用它。

以上所有点赞的答案都是正确的。这是最简单的版本:

private string Serialize(Object o)
{
    using (var writer = new StringWriter())
    {
        new XmlSerializer(o.GetType()).Serialize(writer, o);
        return writer.ToString();
    }
}