entityset.cs

用于c#.net数据库操作的类库。能把结婚集以数组的形成操作。

using System;
using System.IO;
using System.Data;
using System.Runtime.Serialization;
using System.Runtime.Serialization.Formatters.Binary;
using System.Collections;
using System.Diagnostics;

namespace EnterpriseObjects
{
	/// <summary>
	/// Summary description for EntitySet.
	/// </summary>
	public class EntitySet : DataSet, IEnumerable, ICounterProvider
	{
		// members...
		public Type EntityType = typeof(Entity);
		public Hashtable _entityCache;
		public bool UseCaching = true;
		private Hashtable _boundCollections;
		private static PerformanceCounter _entitySetsPerSecond;

		// const
		private const string EntitySetsPerSecondCounterName = "EntitySetsPerSecond";

		public EntitySet()
		{
			//
			// TODO: Add constructor logic here
			//
		}

		protected EntitySet(System.Runtime.Serialization.SerializationInfo info, System.Runtime.Serialization.StreamingContext context) 
			: base(info, context)
		{
		}

		// GetEnumerator - create an enumerator for a table...
		public virtual IEnumerator GetEnumerator()
		{
			return GetEnumerator(0);
		}

		public virtual IEnumerator GetEnumerator(int tableIndex)
		{
			return new EntitySetEnumerator(tableIndex, this);
		}	

		public int Count
		{
			get
			{
				return GetCount(0);
			}
		}

		public int GetCount(int tableIndex)
		{
			return Tables[tableIndex].Rows.Count;
		}

		public Entity GetEntity(int index)
		{
			return GetEntity(0, index);
		}

		public Entity GetEntity(int tableIndex, int index)
		{
			// do we have it in the cache?
			Entity newEntity = null;

			// caching?
			if(UseCaching == true && tableIndex == 0)
			{
				// create it...
				if(_entityCache == null)
					_entityCache = new Hashtable();

				// find it...
				if(_entityCache.Contains(index) == true)
					return (Entity)_entityCache[index];
			}

			// create it...
			newEntity = (Entity)System.Activator.CreateInstance(EntityType);
			newEntity.Populate(Tables[tableIndex].Rows[index]);

			// add it...
			if(UseCaching == true && tableIndex == 0)
				_entityCache.Add(index, newEntity);

			// return...
			return newEntity;
		}

		public void CreateCounters(EnterpriseObjects.EnterpriseCounters counters)
		{
			EnterpriseApplication.Application.Counters.Counters.Add(new EnterpriseCounter(EntitySetsPerSecondCounterName, "The number of EntitySets created each second", PerformanceCounterType.RateOfCountsPerSecond32));
		}

		public void CountersCreated(EnterpriseObjects.EnterpriseCounters counters)
		{
			_entitySetsPerSecond = counters.Counters.Find(EntitySetsPerSecondCounterName).Counter;
		}

		// CreateBoundCollection - create a bound collection...
		public EntityBoundCollection GetBoundCollection(EntitySet entitySet, int tableIndex, Type collectionType)
		{
			// do we have the collection?
			bool inCache = false;
			if(_boundCollections != null)
				inCache = _boundCollections.Contains(tableIndex);
			else
				_boundCollections = new Hashtable();

			// in...
			if(inCache == false)
			{
				// create one...
				EntityBoundCollection collection = (EntityBoundCollection)System.Activator.CreateInstance(collectionType);
				collection.EntitySet = entitySet;
				collection.TableIndex = tableIndex;
				_boundCollections.Add(tableIndex, collection);
			}

			// return
			return (EntityBoundCollection)_boundCollections[tableIndex];
		}

		public void Serialize(Stream stream)
		{
			// formatter...
			BinaryFormatter formatter = new BinaryFormatter();
			Serialize(stream, formatter);
		}

		public void Serialize(Stream stream, IFormatter formatter)
		{
			formatter.Serialize(stream, this);
		}

		public void Serialize(string filename, IFormatter formatter)
		{
			FileStream stream = new FileStream(filename, FileMode.Create);
			Serialize(stream, formatter);
			stream.Close();
		}

		// Deserialize - retrieve from a stream...
		public static EntitySet Deserialize(string filename)
		{
			FileStream stream = new FileStream(filename, FileMode.Open);
			EntitySet newEntitySet = Deserialize(stream);
			stream.Close();
			return newEntitySet;
		}

		public static EntitySet Deserialize(Stream stream)
		{
			// formatter...
			BinaryFormatter formatter = new BinaryFormatter();
			EntitySet newEntitySet = Deserialize(stream, formatter);
			return newEntitySet;
		}

		public static EntitySet Deserialize(string filename, IFormatter formatter)
		{
			FileStream stream = new FileStream(filename, FileMode.Open);
			EntitySet myObject = (EntitySet)Deserialize(stream, formatter);
			stream.Close();
			return myObject;
		}

		public static EntitySet Deserialize(Stream stream, IFormatter formatter)
		{
			EntitySet myObject = (EntitySet)formatter.Deserialize(stream);
			return myObject;
		}
	}
}