"<i>How to resolve System.InvalidOperationException.<\/i>如何解决 System.InvalidOperationException。<\/b> <i>Inaccessible due to its protection level.<\/i>由于其保护级别而无法访问。<\/b> <i>Only public types can be processed<\/i>只能处理公共类型<\/b>"

Question

我正在尝试做一个关于将数据写入和读取到文件的练习。 该程序有房间、客户和酒店类，在我创建对象并为其赋值后，我尝试将其序列化并将其写入 XML 格式的文件，但我遇到了上述异常。 我已经尝试了一个关于这个的例子，它运行正常。 我在某处遗漏了一些声明吗？

这是我的 XMLSerializer.cs：

using System.IO;
using System.Text;
using System.Xml;
using System.Xml.Serialization;

namespace Assignment7
{
    class XMLSerializer
    {
        string filePath;
        public XMLSerializer(string filePath)
        {
            this.filePath = filePath;
        }


        //This generic method serializes (writes) the object of generic data type to the file.
        public string WriteXML<T>(T type)
        {
            StringBuilder feedback = new StringBuilder();
            feedback.AppendLine("Provided data is invalid!");

            if (type == null)
                return feedback.ToString();



            //Here we define an XmlSerializer object
            XmlSerializer xmlSerializer = new XmlSerializer(type.GetType());

            //Here we define an XmlWriter object and define settings for it.
            XmlWriter xmlWriter = XmlWriter.Create(filePath,
                                          new XmlWriterSettings()
                                          {
                                              OmitXmlDeclaration = true,

                                              //ConformanceLevel specifies the level of conformance
                                              //(document, fragment, or automatic detection).
                                              //The default is Document.
                                              ConformanceLevel = ConformanceLevel.Auto,
                                              Indent = true

                                          });


            //Here we serialize data to the file
            xmlSerializer.Serialize(xmlWriter, type);

            //Here we clos ehe stream
            xmlWriter.Close();

            FileInfo fileInfo = new FileInfo(filePath);

            if (fileInfo.Exists)
            {
                feedback.Clear();
                feedback.AppendLine(fileInfo.FullName + " exists? " + fileInfo.Exists + ". Current length: " + fileInfo.Length);

            }

            return feedback.ToString();
        }
    }
}