TextWriter 序列化为 UTF-8 字符串

我使用TextWriter进行序列化，因为在字符串序列化和文件序列化之间切换很容易：

序列化为字符串;

TextWriter stringWriter = new StringWriter();
XmlSerializer serializer = XmlSerializer(typeof(ObjectType))
serializer.Serialize(stringWriter , objetToSerialize)
return stringWriter.ToString();

序列化为文件;

TextWriter fileWriter = new StreamWriter(targetXMLFileName, true, Encoding.UTF8);
XmlSerializer serializer = XmlSerializer(typeof(ObjectType))
serializer.Serialize(fileWriter , objetToSerialize)
fileWriter.Close();

我的问题是，当序列化为字符串时，它会创建一个 UTF-16（"？xml 版本="1.0" 编码="utf-16"？"），并且 TestWriter 编码属性是只读

的

我试过：

var memoryStream = new MemoryStream();
TextWriter stringWriter = new StreamWriter(memoryStream, System.Text.Encoding.UTF8);
XmlSerializer serializer = XmlSerializer(typeof(ObjectType))
serializer.Serialize(stringWriter , objetToSerialize)
return stringWriter.ToString();

但它不起作用。它不是XML文档，而是生成以下字符串："System.IO.StreamWriter"O_o

如何将文本编写器初始化为 UTF-8 编码

string xml = System.Text.Encoding.UTF8.GetString(memoryStream.ToArray());
return xml;