C#: XML Serializer

这里主要讲如何将一个class序列化为一个string。如下一个class:

 public class OrderedItem
     {
         private string itemName;
         private string description;
         private decimal unitPrice;
         private int quantity;
         public string ItemName
         {
             get { return itemName; }
         }
         public string Description
         {
             get { return description; }
         }
         public decimal UnitPrice
         {
             get { return unitPrice; }
         }
         public int Quantity
         {
             get { return quantity; }
         }
         public Dictionary<string, int> Data { get; set; }
         public OrderedItem(string itemName, string description, decimal unitPrice, int quantity)
         {
             this.itemName = itemName;
             this.description = description;
             this.unitPrice = unitPrice;
             this.quantity = quantity;
         }
     }

可以用stringSerializer来实现：

 class StringSerializer
     {
         public static string Serialize<T>(T t)
         {
             using (StringWriter sw = new StringWriter())
             {
                 XmlSerializer xz = new XmlSerializer(t.GetType());
                 xz.Serialize(sw, t);
                 return sw.ToString();
             }
         }
         public static object Deserialize(Type t, string s)
         {
             using (StringReader sr = new StringReader(s))
             {
                 XmlSerializer xz = new XmlSerializer(t);
                 return xz.Deserialize(sr);
             }
         }
     }

这里会有这么几个问题：

1. Dictionary并不直接支持序列化，因此需要包装一下，如下：

 public class SerializableDictionary<TKey, TValue> : Dictionary<TKey, TValue>, IXmlSerializable
     {
         public XmlSchema GetSchema()
         {
             throw new NotImplementedException();
         }
         public void ReadXml(XmlReader reader)
         {
             XmlSerializer keySerializer = new XmlSerializer(typeof(TKey));
             XmlSerializer valueSerializer = new XmlSerializer(typeof(TValue));
             bool isEmpty = reader.IsEmptyElement;
             reader.Read();
             if (isEmpty)
                 return;
             while (reader.NodeType != System.Xml.XmlNodeType.EndElement)
             {
                 reader.ReadStartElement("item");
                 reader.ReadStartElement("key");
                 TKey key = (TKey)keySerializer.Deserialize(reader);
                 reader.ReadEndElement();
                 reader.ReadStartElement("value");
                 TValue value = (TValue)valueSerializer.Deserialize(reader);
                 reader.ReadEndElement();
                 this.Add(key, value);
                 reader.ReadEndElement();
                 reader.MoveToContent();
             }
             reader.ReadEndElement();

         }

         public void WriteXml(System.Xml.XmlWriter writer)
         {
             XmlSerializer keySerializer = new XmlSerializer(typeof(TKey));
             XmlSerializer valueSerializer = new XmlSerializer(typeof(TValue));
             foreach (TKey key in this.Keys)
             {
                 writer.WriteStartElement("item");
                 writer.WriteStartElement("key");
                 keySerializer.Serialize(writer, key);
                 writer.WriteEndElement();
                 writer.WriteStartElement("value");
                 TValue value = this[key];
                 valueSerializer.Serialize(writer, value);
                 writer.WriteEndElement();
                 writer.WriteEndElement();
             }

         }
     }

2. 被序列化的类必须有无参的构造函数。

3. 属性访问器必须有get和set。

最后OrderedItem类应如下所示

 public class OrderedItem
     {
         private string itemName;
         private string description;
         private decimal unitPrice;
         private int quantity;
         public string ItemName
         {
             get { return itemName; }
             set { itemName = value; }
         }
         public string Description
         {
             get { return description; }
             set { description = value; }
         }
         public decimal UnitPrice
         {
             get { return unitPrice; }
             set { unitPrice = value; }
         }
         public int Quantity
         {
             get { return quantity; }
             set { quantity = value; }
         }
         public SerializableDictionary<string, int> Data { get; set; }
         public OrderedItem()
         {
         }
         public OrderedItem(string itemName, string description, decimal unitPrice, int quantity)
         {
             this.itemName = itemName;
             this.description = description;
             this.unitPrice = unitPrice;
             this.quantity = quantity;
         }
     }

可以测试一下：

 class Program
     {
         static void Main(string[] args)
         {
             OrderedItem test = );
             test.Data = new SerializableDictionary<string, int>();
             test.Data.Add();
             test.Data.Add();
             string str = StringSerializer.Serialize(test);
             Console.WriteLine(str);
             OrderedItem result = StringSerializer.Deserialize(typeof(OrderedItem), str) as OrderedItem;
             Console.WriteLine("result: " +
                 "\n\t ItemName: " + result.ItemName +
                 "\n\t Description: " + result.Description +
                 "\n\t UnitPrice: " + result.UnitPrice +
                 "\n\t Quantity: " + result.Quantity +
                 "\n\t Data: ");
             foreach (var item in result.Data)
             {
                 Console.WriteLine("\t Key: " + item.Key + "\t Value: " + item.Value);
             }
         }

     }

结果如下：