写的反序列化函数总是出现问题。加上Seek()或设置Position也不能解决问题
System.Runtime.Serialization.SerializationException: 在分析完成之前就遇到流结尾。  
      public static Object ReadObject(string readPath)
        {
            FileStream fs = null;
            try
            {
                fs = new FileStream(readPath, FileMode.OpenOrCreate, FileAccess.Read);
                BinaryFormatter bf = new BinaryFormatter();
                Object obj = bf.Deserialize(fs);
                return obj;
            }
            catch (Exception)
            {
                return null;
            }
            finally 
            {
                fs.Close();
            }
        }