oledbfactory.cs

抽象工厂的典型实现

using System;
using System.Data;
using System.Data.Common;

namespace DataAccess
{
	/// <summary>
	/// OleDbFactory: OleDb具体工厂
	/// </summary>
	public class OleDbFactory : DbFactory
	{
		public OleDbFactory() {}

		public override IDbConnection CreateConnection()
		{
			return new System.Data.OleDb.OleDbConnection();
		}
		public override IDbConnection CreateConnection(string connectionString)
		{
			return new System.Data.OleDb.OleDbConnection(connectionString);
		}

		public override IDbDataAdapter CreateAdapter()
		{
			return new System.Data.OleDb.OleDbDataAdapter();
		}
		public override IDbDataAdapter CreateAdapter(IDbCommand selectCommand)
		{
			return new System.Data.OleDb.OleDbDataAdapter((System.Data.OleDb.OleDbCommand)selectCommand);
		}
		public override IDbDataAdapter CreateAdapter(string selectCommandText, IDbConnection selectConnection)
		{
			return new System.Data.OleDb.OleDbDataAdapter(selectCommandText, (System.Data.OleDb.OleDbConnection)selectConnection);
		}
		public override IDbDataAdapter CreateAdapter(string selectCommandText, string selectConnectionString)
		{
			return new System.Data.OleDb.OleDbDataAdapter(selectCommandText, selectConnectionString);
		}

		public override IDbCommand CreateCommand()
		{
			return new System.Data.OleDb.OleDbCommand();
		}
		public override IDbCommand CreateCommand(string cmdText)
		{
			return new System.Data.OleDb.OleDbCommand(cmdText);
		}
		public override IDbCommand CreateCommand(string cmdText, IDbConnection connection)
		{
			return new System.Data.OleDb.OleDbCommand(cmdText, (System.Data.OleDb.OleDbConnection)connection);
		}
		public override IDbCommand CreateCommand(string cmdText, IDbConnection connection, IDbTransaction transaction)
		{
			return new System.Data.OleDb.OleDbCommand(cmdText, (System.Data.OleDb.OleDbConnection)connection, (System.Data.OleDb.OleDbTransaction)transaction);
		}

		public override DbCommandBuilder CreateCommandBuilder()
		{
			return new DataAccess.OleDbCommandBuilder();
		}
		public override DbCommandBuilder CreateCommandBuilder(IDbDataAdapter adapter)
		{
			return new DataAccess.OleDbCommandBuilder(adapter);
		}

		protected override void AppendItem(IDbCommand cmd, ConditionList.ConditionItem item, bool bFirst)
		{
			if(bFirst)
				cmd.CommandText += " WHERE";
			else
				cmd.CommandText += " AND";

			if(item.FieldValue is DBNull)
				cmd.CommandText += String.Format(" {0} IS NULL", item.FieldName);
			else if(item.Relation == '%')
				cmd.CommandText += String.Format(" {0} LIKE '%{1}%'", item.FieldName, item.FieldValue);
			else
			{
				cmd.CommandText += String.Format(" {0} {1} ?", item.FieldName, item.Relation);
				IDbDataParameter param = cmd.CreateParameter();
				param.SourceColumn = item.FieldName;
				param.Value = item.FieldValue;
				cmd.Parameters.Add(param);
			}
		}
		public override void AppendCommandCondition(IDbCommand cmd, string clause, string fieldName, String relation, object fieldValue)
		{
			IDbDataParameter param = cmd.CreateParameter();
			param.SourceColumn = fieldName;
			param.ParameterName = "p" + (nParam++);
			param.Value = fieldValue;
			cmd.CommandText += String.Format(" {0} {1} {2} ?", clause, fieldName, relation);
			cmd.Parameters.Add(param);
		}

		public override IDbCommand CreateIdentityGetter(string tableName)
		{
			throw new ApplicationException("Function Not Implemented");
		}

		public override IDbInitiationHelper CreateInitiationHelper( IDbConnection connection )
		{
			return new OleDbInitiationHelper(connection);
		}

		public override IDbInitiationHelper CreateInitiationHelper( string connectionString )
		{
			return new OleDbInitiationHelper(connectionString);
		}
	}

}