XML Serializable Generic Dictionary

/// <summary>
    /// 支持XML序列化的泛型 Dictionary
    /// </summary>
    /// <typeparam name="TKey"></typeparam>
    /// <typeparam name="TValue"></typeparam>
    [XmlRoot("dictionary")]
    public class SerializableDictionary<TKey, TValue> 
        : Dictionary<TKey, TValue>, IXmlSerializable
    {

 #region 构造函数
        public SerializableDictionary():base()
        {
        }
        
        public SerializableDictionary(IDictionary<TKey, TValue> dictionary):base(dictionary)
        {
        }
            
       
        public SerializableDictionary(IEqualityComparer<TKey> comparer):base(comparer)
        {
        }
       
        public SerializableDictionary(int capacity):base(capacity)
        {
        }
       
        public SerializableDictionary(int capacity, IEqualityComparer<TKey> comparer)
            :base(capacity,comparer)
        {
        }
        protected SerializableDictionary(SerializationInfo info, StreamingContext context):base(info,context)
        {
        }
        #endregion
        #region IXmlSerializable Members 
        public System.Xml.Schema.XmlSchema GetSchema()
        {   
            return null;   
        }     

        /// <summary>
        /// 从对象的 XML 表示形式生成该对象
        /// </summary>
        /// <param name="reader"></param>
        public void ReadXml(System.Xml.XmlReader reader)
        {

            XmlSerializer keySerializer = new XmlSerializer(typeof(TKey));
            XmlSerializer valueSerializer = new XmlSerializer(typeof(TValue)); 
            bool wasEmpty = reader.IsEmptyElement;   
            reader.Read();     

            if (wasEmpty)   
                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();

        }


        /// <summary>
        /// 将对象转换为其 XML 表示形式
        /// </summary>
        /// <param name="writer"></param>
        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();
            }

        }

        #endregion

    }