serializer.cs

本系统是在asp版《在线文件管理器》的基础上设计制作

//------------------------------------------------------------------------------
// <copyright company="Telligent Systems">
//     Copyright (c) Telligent Systems Corporation.  All rights reserved.
// </copyright> 
//------------------------------------------------------------------------------

using System;
using System.IO;
using System.Collections.Specialized;
using System.Globalization;
using System.Security;
using System.Security.Permissions;
using System.Runtime.Serialization;
using System.Runtime.Serialization.Formatters.Binary;
using System.Text;
using System.Xml;
using System.Xml.Serialization;

namespace CommunityServer.Components
{
	/// <summary>
	/// Summary description for Serializer.
	/// </summary>
	public class Serializer
	{
        //Do not allow this class to be instantiated
		private Serializer()
		{
		
		}

        /// <summary>
        /// Static Constructor is used to set the CanBinarySerialize value only once for the given security policy
        /// </summary>
        static Serializer()
        {
            SecurityPermission sp =  new SecurityPermission(SecurityPermissionFlag.SerializationFormatter);
            try
            {
                sp.Demand();
                CanBinarySerialize = true;
            }
            catch(SecurityException)
            {
                CanBinarySerialize = false;
            }
        }

        /// <summary>
        /// Readonly value indicating if Binary Serialization (using BinaryFormatter) is allowed
        /// </summary>
        public static readonly bool CanBinarySerialize;

        /// <summary>
        /// Converts a .NET object to a byte array. Before the conversion happens, a check with 
        /// Serializer.CanBinarySerialize will be made
        /// </summary>
        /// <param name="objectToConvert">Object to convert</param>
        /// <returns>A byte arry representing the object paramter. Null will be return if CanBinarySerialize is false</returns>
        public static byte[] ConvertToBytes(object objectToConvert)
        {
            byte[] byteArray = null;

            if(CanBinarySerialize)
            {
                BinaryFormatter	binaryFormatter	= new BinaryFormatter();
                using(MemoryStream ms	= new MemoryStream())
                {

                    binaryFormatter.Serialize(ms, objectToConvert);
            

                    // Set the position	of the MemoryStream	back to	0
                    //
                    ms.Position	= 0;
			
                    // Read	in the byte	array
                    //
                    byteArray =	new	Byte[ms.Length];
                    ms.Read(byteArray, 0, byteArray.Length);
                    ms.Close();
                }
            }
            return byteArray;
        }

		/// <summary>
		/// Saves an object to disk as a binary file. 
		/// </summary>
		/// <param name="objectToSave">Object to Save</param>
		/// <param name="path">Location of the file</param>
		/// <returns>true if the save was succesful.</returns>
		public static bool SaveAsBinary(object objectToSave, string path)
		{
			if(objectToSave != null && CanBinarySerialize)
			{
				byte[] ba = ConvertToBytes(objectToSave);
				if(ba != null)
				{
					using(FileStream fs = new FileStream(path,FileMode.OpenOrCreate,FileAccess.Write))
					{
						using(BinaryWriter bw = new BinaryWriter(fs))
						{
							bw.Write(ba);
							return true;
						}
					}
				}
			}
			return false;
		}


        /// <summary>
        /// Converts a .NET object to a string of XML. The object must be marked as Serializable or an exception
        /// will be thrown.
        /// </summary>
        /// <param name="objectToConvert">Object to convert</param>
        /// <returns>A xml string represting the object parameter. The return value will be null of the object is null</returns>
        public static string ConvertToString(object objectToConvert)
        {
            string xml = null;
           
            if(objectToConvert != null)
            {
                //we need the type to serialize
                Type t = objectToConvert.GetType();

                XmlSerializer ser = new XmlSerializer(t);
                //will hold the xml
                using(StringWriter writer = new StringWriter(CultureInfo.InvariantCulture))
                {
                    ser.Serialize(writer, objectToConvert);
                    xml =  writer.ToString();
                    writer.Close();
                }
            }
            
            return xml;
        }

		public static void SaveAsXML(object objectToConvert, string path)
		{
			if(objectToConvert != null)
			{
				//we need the type to serialize
				Type t = objectToConvert.GetType();

				XmlSerializer ser = new XmlSerializer(t);
				//will hold the xml
				using(StreamWriter writer = new StreamWriter(path))
				{
					ser.Serialize(writer, objectToConvert);
					writer.Close();
				}
			}
            
		}


        /// <summary>
        /// Converts a byte array to a .NET object. You will need to cast this object back to its expected type. 
        /// If the array is null or empty, it will return null.
        /// </summary>
        /// <param name="byteArray">An array of bytes represeting a .NET object</param>
        /// <returns>The byte array converted to an object or null if the value of byteArray is null or empty</returns>
        public static object ConvertToObject(byte[] byteArray)
        {
            object convertedObject = null;
            if(CanBinarySerialize && byteArray != null && byteArray.Length > 0)
            {
                BinaryFormatter	binaryFormatter	= new BinaryFormatter();
                using(MemoryStream ms	= new MemoryStream())
                {
                    ms.Write(byteArray, 0, byteArray.Length);

                    // Set the memory stream position to the beginning of the stream
                    //
                    ms.Position	= 0;

                    if( byteArray.Length > 4 )
                        convertedObject = binaryFormatter.Deserialize(ms);

                    ms.Close();
                }
            }
            return convertedObject;
        }

        public static object ConvertFileToObject(string path, Type objectType)
        {
            object convertedObject = null;

            if(path != null && path.Length > 0)
            {
                using(FileStream fs = new FileStream(path,FileMode.Open,FileAccess.Read))
                {
                    XmlSerializer ser = new XmlSerializer(objectType);
                    convertedObject = ser.Deserialize(fs);
                    fs.Close();
                }
            }
            return convertedObject;
        }

        /// <summary>
        /// Converts a string of xml to the supplied object type. 
        /// </summary>
        /// <param name="xml">Xml representing a .NET object</param>
        /// <param name="objectType">The type of object which the xml represents</param>
        /// <returns>A instance of object or null if the value of xml is null or empty</returns>
        public static object ConvertToObject(string xml, Type objectType)
        {
            object convertedObject = null;

            if(!Globals.IsNullorEmpty(xml))
            {
                using(StringReader reader  = new StringReader(xml))
                {
                    XmlSerializer ser = new XmlSerializer(objectType);
                    convertedObject = ser.Deserialize(reader);
                    reader.Close();
                }
            }
            return convertedObject;
        }

		public static object LoadBinaryFile(string path)
		{
            if(!File.Exists(path))
                return null;

			using(FileStream fs = new FileStream(path,FileMode.Open,FileAccess.Read))
			{
				BinaryReader br =new BinaryReader(fs);
				byte[] ba = new byte[fs.Length];
				br.Read(ba,0,(int)fs.Length);
				return ConvertToObject(ba);
			}
		}

        /// <summary>
        /// Creates a NameValueCollection from two string. The first contains the key pattern and the second contains the values
        /// spaced according to the kys
        /// </summary>
        /// <param name="keys">Keys for the namevalue collection</param>
        /// <param name="values">Values for the namevalue collection</param>
        /// <returns>A NVC populated based on the keys and vaules</returns>
        /// <example>
        /// string keys = "key1:S:0:3:key2:S:3:2:";
        /// string values = "12345";
        /// This would result in a NameValueCollection with two keys (Key1 and Key2) with the values 123 and 45
        /// </example>
        public static NameValueCollection ConvertToNameValueCollection(string keys, string values)
        {
            NameValueCollection nvc  = new NameValueCollection();

            if(keys != null && values != null && keys.Length > 0 && values.Length > 0)
            {
                char[] splitter = new char[1] { ':' } ;
                string[] keyNames = keys.Split(splitter);
				 
                for (int i = 0; i < (keyNames.Length / 4); i++)
                {					
                    int start = int.Parse(keyNames[(i * 4) + 2], CultureInfo.InvariantCulture);
                    int len = int.Parse(keyNames[(i * 4) + 3], CultureInfo.InvariantCulture);
                    string key = keyNames[i * 4];
						
                    //Future version will support more complex types	
                    if (((keyNames[(i * 4) + 1] == "S") && (start >= 0)) && (len > 0) && (values.Length >= (start + len)))
                    {
                        nvc[key] = values.Substring(start, len);
                    }
                }
            }
				
            return nvc;
        }

        /// <summary>
        /// Creates a the keys and values strings for the simple serialization based on a NameValueCollection
        /// </summary>
        /// <param name="nvc">NameValueCollection to convert</param>
        /// <param name="keys">the ref string will contain the keys based on the key format</param>
        /// <param name="values">the ref string will contain all the values of the namevaluecollection</param>
        public static void ConvertFromNameValueCollection(NameValueCollection nvc, ref string keys, ref string values)
        {
            if(nvc == null || nvc.Count == 0)
                return;

            StringBuilder sbKey = new StringBuilder();
            StringBuilder sbValue = new StringBuilder();
		
            int index = 0;
            foreach(string key in nvc.AllKeys)
            {
                if(key.IndexOf(':') != -1)
                    throw new ArgumentException("ExtendedAttributes Key can not contain the character \":\"");

                string v = nvc[key];
				if(!Globals.IsNullorEmpty(v))
				{
					sbKey.AppendFormat("{0}:S:{1}:{2}:",key,index,v.Length);
					sbValue.Append(v);
					index += v.Length;
				}
            }
            keys = sbKey.ToString();
            values = sbValue.ToString();
        }
	}
}