开发自己的Data Access Application Block[下篇]

上接： [原创] 我的ORM: 开发自己的Data Access Application Block - Part I 4. Database 下面来介绍重中之重：Database，绝大部分的DataAccess 操作都集中在这个Abstract Database中。这是一个相对庞大的Class，所以不得不采用Partial Class的方式来编写。

下面来介绍重中之重：database，绝大部分的data access 操作都集中在这个abstract database中。这是一个相对庞大的class，所以不得不采用partial class的方式来编写。

Part I：Field 和Property

这些Field 和Property基本上对应我们前面的Configuraiton。此为我们定义了三个Field 和Property：DbDataAdapter，Connection，_transaction。考虑到垃圾回收，使Database实现IDisposable接口。值得说明一点的是，我们通过Database的DatabaseProviderFactory创建了泛型的DbDataAdapter，DbConnection和Transaction。

• ConnectionString：string

• DatabaseProviderFactory：DbProviderFactory

• DefaultCommandType：CommandType

• UseCommandBuilder：bool

• DbParameterNameMapping：IDbParameterNameMapping

• StoredProcedureNameMapping：IStoredProcedureNameMapping

• DbDataAdapter：DbDataAdapter

• Connection: DbConnection

• Transaction: DbTransaction

using System;
using System.Collections.Generic;
using System.Text;
using System.Data;
using System.Data.Common;

using Artech.ApplicationBlock.DataMapping;

namespace Artech.ApplicationBlock.DataAccess
{
    /**//// 

    

 Database defines a series of database-based operations.
    

 Database : IDisposable
    

{
        private bool _isDisposed;

        The five private fields possess the corressponding pubic properties, and they are only allowed to be evaluated by Database Factory.#region The five private fields possess the corressponding pubic properties, and they are only allowed to be evaluated by Database Factory.
        private DbProviderFactory _dbProviderFactory;
        private string _connectionString;
        private CommandType _defaultCommandType;
        private bool _useCommandBuilder;
        private IDbParameterNameMapping _dbParameterNameMapping;
        private IStoredProcedureNameMapping _storedProcedureNameMapping;

        /**//// 

        /// Database connection string which is specified by the database factory.
        /// 
        public string ConnectionString
        {
            get
            {
                return this._connectionString;
            }

            set
            {
                this._connectionString = value;
            }
        }

        /**//// 

        /// The concrete database specific provider factory.
        /// 
        public DbProviderFactory DatabaseProviderFactory
        {
            get
            {
                return this._dbProviderFactory;
            }
            set
            {
                this._dbProviderFactory = value;
            }
        }

        /**//// 

        /// The defaull command type to perform the database operations which do not specify the commanf type.
        /// 
        public CommandType DefaultCommandType
        {
            get
            {
                return this._defaultCommandType;
            }
            set
            {
                this._defaultCommandType = value;
            }
        }

        /**//// 

        ///Determine whether to use command builder or mapped stored procedures to execute database operations.
        /// 
        public bool UseCommandBuilder
        {
            get
            {
                return this._useCommandBuilder;
            }
            set
            {
                this._useCommandBuilder = value;
            }
        }

        /**//// 

        /// A string which indicates the type to perform mapping between stored procedure parameter and source column.
        /// 
        public IDbParameterNameMapping DbParameterNameMapping
        {
            get
            {
                return this._dbParameterNameMapping;
            }
            set
            {
                this._dbParameterNameMapping = value;
            }
        }

        /**//// 

        /// A string which indicates the type to perform mapping between table name and the related stored procedure names.
        /// 
        public IStoredProcedureNameMapping StoredProcedureNameMapping
        {
            get
            {
                return this._storedProcedureNameMapping;
            }
            set
            {
                this._storedProcedureNameMapping = value;
            }
        }
        #endregion

        Connection & Database DataAdapter#region Connection & Database DataAdapter
        private DbDataAdapter _dbDataAdapter;
        private DbConnection _connection;

        /**//// 

        /// A generic database data adapter which is responsible for save the changed data into database.
        /// 
        private DbDataAdapter DatabaseAdapter
        {
            get
            {
                if (this._dbDataAdapter == null)
                {
                    this._dbDataAdapter = this._dbProviderFactory.CreateDataAdapter();
                    this._dbDataAdapter.AcceptChangesDuringUpdate = false;
                    this._dbDataAdapter.MissingSchemaAction = MissingSchemaAction.Add;
                }

                return this._dbDataAdapter;
            }
        }

        /**//// 

        /// The database connection.
        /// 
        private DbConnection Connection
        {
            get
            {
                if (this._connection == null)
                {
                    this._connection = this._dbProviderFactory.CreateConnection();
                    this._connection.ConnectionString = this._connectionString;
                }

                return this._connection;
            }
        }
        #endregion

        Constructor#region Constructor
        public Database()
    &