C# xml序列化实现及遇到的坑

/// <summary>
/// 对象转化为xml字符串
/// </summary>
/// <param name="obj"></param>
/// <returns></returns>
public static string ObjectToXmlString(object obj, bool isNeedHeader = false, bool isFormat = false)
{
    try
    {
        XmlSerializer xmlSerializer = new XmlSerializer(obj.GetType());
        XmlWriterSettings settings = new XmlWriterSettings();
        settings.Encoding = Encoding.UTF8;
        if (isFormat)
        {
            settings.Indent = true;
            settings.IndentChars = "    ";
            settings.NewLineChars = "\r\n";
        }
        if (!isNeedHeader)
        {
            settings.OmitXmlDeclaration = true;  // 不生成声明头
        }
        using (var memoryStream = new MemoryStream())
        using (XmlWriter xmlWriter = XmlWriter.Create(memoryStream, settings))
        {
            // 强制指定命名空间，覆盖默认的命名空间
            XmlSerializerNamespaces namespaces = new XmlSerializerNamespaces();
            namespaces.Add(string.Empty, string.Empty);
            xmlSerializer.Serialize(xmlWriter, obj, namespaces);
            var xmlString = Encoding.UTF8.GetString(memoryStream.ToArray());
            return xmlString;
        };
    }
    catch
    {
        return string.Empty;
    }
}

var a1= Encoding.UTF8.GetBytes("<");
var a2 = Encoding.UTF8.GetBytes("<");

/// <summary>
/// 对象转化为xml字符串
/// </summary>
/// <param name="obj"></param>
/// <param name="isNeedHeader">是否需要xml声明头，默认不需要</param>
/// <param name="isFormat">是否需要格式化xml，默认不需要</param>
/// <returns></returns>
public static string ObjectToXmlString(object obj, bool isNeedHeader = false, bool isFormat = false)
{
    try
    {
        XmlSerializer xmlSerializer = new XmlSerializer(obj.GetType());
        XmlWriterSettings settings = new XmlWriterSettings();
        settings.Encoding = new UTF8Encoding(false);//utf-8不带BOM //Encoding.UTF8;//utf-8带BOM
        if (isFormat)
        {
            settings.Indent = true;
            settings.IndentChars = "    ";
            settings.NewLineChars = "\r\n";
        }
        if (!isNeedHeader)
        {
            settings.OmitXmlDeclaration = true;  // 不生成声明头
        }
        using (var memoryStream = new MemoryStream())
        using (XmlWriter xmlWriter = XmlWriter.Create(memoryStream, settings))
        {
            // 强制指定命名空间，覆盖默认的命名空间
            XmlSerializerNamespaces namespaces = new XmlSerializerNamespaces();
            namespaces.Add(string.Empty, string.Empty);
            xmlSerializer.Serialize(xmlWriter, obj, namespaces);
            var xmlString = Encoding.UTF8.GetString(memoryStream.ToArray());
            return xmlString;
        };
    }
    catch
    {
        return string.Empty;
    }
}