現在可選的框架

??? 現在我們開發一個.net應用，面臨的選擇比較多。我們可以選擇entity framework, enterprise library, nhibernate, 還有一個mybatis.net, 即java世界mybatis/ibatis的.net版。?IOC的框架可以選擇Unity, Ninject，Spring.net(java的spring對應的.net版本)。Entity framework可以使用linq查詢，有好幾種開發模式，如code first, db first, 可以不用寫sql。Entity framework適合sql server。雖有mysql提供了entity framework的provider，但是不是很好, 經常不得不單獨寫sql來操作mysql. Enterprise library是個不錯的選擇，有log, exception, policy injection的一些東西，操作數據庫也比較好。nhibernate是java版hibernate的.net對應版本。對數據庫包裝得比較多，可以不用寫sql. 但是有些時候對數據庫操作不夠優化，會有一些多余數據庫操作。帶來一些性能的影響。mybatis.net是個介于ado.net與nhibernate之間的框架，它負責數據庫對象與內存對象的映射。程序員必須寫sql語句來操作數據庫。IOC的框架中Unity, Ninject, Spring.net, 都是不錯的框架。有時這些框架能照顧到我們大部分的需求，也有一些情況，不能全部照顧到我們的需求。這時就得用一些老辦法。比如直接就用ado.net

適應多種數據庫的db helper代碼

??? 這里主要是想說一些基于ado.net來開發asp.net mvc應用的一些思路。為什么選用ado.net呢，ado.net性能可以達到最好，靈活。先看一段db helper的代碼:

using System; using System.Configuration; using System.Data; using System.Data.Common; using System.Collections.Generic;namespace DataAccessCommon {/// <summary>/// The MyDBHelper class is intended to encapsulate high performance, scalable best practices for /// common uses of SqlClient, OracleClient, OleDb, and others/// </summary>public static class MyStaticDBHelper{public struct MyDBParameter{public string strParameterName;public DbType dbType;public object value;public ParameterDirection parameterDirection;public MyDBParameter(string parameterName, DbType type, object theValue, ParameterDirection direction = ParameterDirection.Input){strParameterName = parameterName;dbType = type;value = theValue;parameterDirection = direction;}}public static string DatabaseType = "SqlServer";private static Dictionary<string, string> providers = new Dictionary<string, string>() {{ "SqlServer", "System.Data.SqlClient" }, { "Oracle", "System.Data.OracleClient" }, { "OleDb", "System.Data.OleDb" } };private static DbProviderFactory dataFactory = DbProviderFactories.GetFactory(providers[DatabaseType]);public static string CONNECTION_STRING = ConfigurationManager.AppSettings["ConnectionString"];#region private methodsprivate static void AttachParameters(DbCommand command, DbParameter[] parameters){if (parameters != null){command.Parameters.AddRange(parameters);}}private static DbCommand CreateCommand(object conn){DbCommand command = null;//If it is just a connection(not a transaction)if (conn is DbConnection){command = ((DbConnection)conn).CreateCommand();if (command.Connection.State != ConnectionState.Open){command.Connection.Open();}}else //It is a transaction, then join the transaction {command = ((DbTransaction)conn).Connection.CreateCommand();command.Transaction = (DbTransaction)conn;}return command;}private static DbCommand SetupCommand(object conn, CommandType commandType, string strSQLOrSPName, List<MyDBParameter> myDBParameters){DbParameter[] parameters = myDBParameters != null ? CreateDBParameters(myDBParameters).ToArray() : null;DbCommand command = CreateCommand(conn);command.CommandText = strSQLOrSPName;command.CommandType = commandType;AttachParameters(command, parameters);return command;}private static DbParameter CreateDBParameter(string strParameterName, DbType dbType, object value, ParameterDirection direction){DbParameter parameter = dataFactory.CreateParameter();parameter.ParameterName = strParameterName;parameter.DbType = dbType;parameter.Value = value;parameter.Direction = direction;return parameter;}private static List<DbParameter> CreateDBParameters(List<MyDBParameter> myDBParameters){List<DbParameter> parameters = new List<DbParameter>();foreach (MyDBParameter myDBParameter in myDBParameters){parameters.Add(CreateDBParameter(myDBParameter.strParameterName, myDBParameter.dbType, myDBParameter.value, myDBParameter.parameterDirection));}return parameters;}#endregionpublic static DbConnection GetConnection(){DbConnection connection = dataFactory.CreateConnection();connection.ConnectionString = CONNECTION_STRING;return connection;}public static int ExecuteNonQuery(object conn, CommandType commandType, string strSQLOrSPName, List<MyDBParameter> myDBParameters = null){DbCommand command = SetupCommand(conn, commandType, strSQLOrSPName, myDBParameters);return command.ExecuteNonQuery();}public static DataSet ExecuteDataset(object conn, CommandType commandType, string strSQLOrSPName, List<MyDBParameter> myDBParameters = null){DbCommand command = SetupCommand(conn, commandType, strSQLOrSPName, myDBParameters);DbDataAdapter dataAdaptor = dataFactory.CreateDataAdapter();DataSet ds = new DataSet();dataAdaptor.SelectCommand = command;dataAdaptor.Fill(ds);return ds;}public static DbDataReader ExecuteReader(object conn, CommandType commandType, string strSQLOrSPName, List<MyDBParameter> myDBParameters = null){DbCommand command = SetupCommand(conn, commandType, strSQLOrSPName, myDBParameters);return command.ExecuteReader();}public static object ExecuteScalar(object conn, CommandType commandType, string strSQLOrSPName, List<MyDBParameter> myDBParameters = null){DbCommand command = SetupCommand(conn, commandType, strSQLOrSPName, myDBParameters);return command.ExecuteScalar();}} }

此代碼能支持訪問Oracle, sql server, OleDB。用的都是DbConnection之類的。只要開始選擇了正確的provider, DbProviderFactories就給創建相應的connection, command等類，就可以順利地處理這個對應的數據庫了。sql的參數是DbType。用來適應數據庫類型。MyDBParameter結構封裝了參數名，類型，參數值，傳入傳出方向。目前的版本只考慮了一個數據庫連接。連接串只有一個。DbProviderFactory只有一個實例。沒有考慮到動態切換連接的情況。如果是要多個連接，得要多個DbProviderFactory的實例。CreateCommand方法里判斷了傳入的的數據庫連接是一個DbConnection還是一個DbTransaction，如果是一個DbTransaction的話，可以加入這個數據庫事務。如果只是一個DbConnection則不加入已有的數據庫事務，使用自動的數據庫事務。

數據實體類

using System; using System.Collections.Generic;namespace DataEntity {public class UserMenuItem{#region Propertiespublic int MenuItemID { get; set; }public string MenuItemName { get; set; }public int MenuID { get; set; }public int Ordinal { get; set; }public int Indent { get; set; }#endregion} }

純數據的類。這里使用了比較老的c#語法。也可以加上DataAnnotation的標簽。可以實現驗證數據，也可以加上Display標簽，引用資源文件。這個數據實體類在MVC頁面里綁定時可以顯示想應的label。label的內容來自于資源文件，便于使用多語言的界面。

using System; using System.Collections.Generic; using System.ComponentModel.DataAnnotations; using Resource.Entity;namespace DataEntity {public class UserAccount{#region Propertiespublic int ID { get; set; }[Required(ErrorMessageResourceType=typeof(Resource.Entity.UserAccount), ErrorMessageResourceName="Common_Required_ErrorMessage")][StringLength(30, ErrorMessageResourceType=typeof(Resource.Entity.UserAccount), ErrorMessageResourceName = "NAME_StringLength_ErrorMessage")][RegularExpression(@"[a-zA-Z].*", ErrorMessageResourceType=typeof(Resource.Entity.UserAccount), ErrorMessageResourceName = "NAME_RegularExpression_ErrorMessage")][Display(ResourceType=typeof(Resource.Entity.UserAccount), Name="NAME_DisplayName")]public string Name { get; set; }[Required(ErrorMessageResourceType=typeof(Resource.Entity.UserAccount), ErrorMessageResourceName = "Common_Required_ErrorMessage")][RegularExpression(@"[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?", ErrorMessageResourceType=typeof(Resource.Entity.UserAccount), ErrorMessageResourceName="EMAIL_RegularExpression_ErrorMessage")][Display(ResourceType=typeof(Resource.Entity.UserAccount), Name="EMAIL_DisplayName")]public string Email { get; set; }[Display(ResourceType = typeof(Resource.Entity.UserAccount), Name = "PASSWORD_DisplayName")][Required(ErrorMessageResourceType = typeof(Resource.Entity.UserAccount), ErrorMessageResourceName = "Common_Required_ErrorMessage")][StringLength(32, ErrorMessageResourceType = typeof(Resource.Entity.UserAccount), ErrorMessageResourceName = "PASSWORD_StringLength", MinimumLength = 8)]public string Password { get; set; }[Display(ResourceType = typeof(Resource.Entity.UserAccount), Name = "Balance")]public decimal Balance { get; set; }[Required(ErrorMessageResourceType = typeof(Resource.Entity.UserAccount), ErrorMessageResourceName = "Common_Required_ErrorMessage")][Display(ResourceType = typeof(Resource.Entity.UserAccount), Name = "CONFIRMPASSWORD_DisplayName")][Compare("Password", ErrorMessageResourceType = typeof(Resource.Entity.UserAccount), ErrorMessageResourceName = "CONFIRMPASSWORD_CompareErrorMessage")]public string ConfirmPassword { get; set; }[Required(ErrorMessageResourceType = typeof(Resource.Entity.UserAccount), ErrorMessageResourceName = "Common_Required_ErrorMessage")][Display(ResourceType = typeof(Resource.Entity.UserAccount), Name = "OLDNAME_DisplayName")]public string OldName { get; set; }[Required(ErrorMessageResourceType = typeof(Resource.Entity.UserAccount), ErrorMessageResourceName = "Common_Required_ErrorMessage")][Display(ResourceType = typeof(Resource.Entity.UserAccount), Name = "OLDEMAIL_DisplayName")]public string OldEmail { get; set; }[Required(ErrorMessageResourceType = typeof(Resource.Entity.UserAccount), ErrorMessageResourceName = "Common_Required_ErrorMessage")][Display(ResourceType = typeof(Resource.Entity.UserAccount), Name = "OLDPassword_DisplayName")]public string OldPassword { get; set; }#endregion} }

?

下面是數據訪問的代碼:

using System; using System.Collections.Generic; using System.Data; using DataEntity; using DataAccessCommon;namespace DataAccess {public class DALUserMenuItem{#region data access methodspublic int DeleteUserMenuItem(Object conn, UserMenuItem usermenuitem){List<MyStaticDBHelper.MyDBParameter> paras = new List<MyStaticDBHelper.MyDBParameter> {new MyStaticDBHelper.MyDBParameter("@MenuItemID", DbType.Int32, usermenuitem.MENUITEMID)};string strSQL = "DELETE FROM [UserMenuItem] WHERE [MenuItemID] = @MenuItemID";int result = 0;result = MyStaticDBHelper.ExecuteNonQuery(conn, System.Data.CommandType.Text, strSQL, paras);return result;}public int UpdateUserMenuItem(Object conn, UserMenuItem usermenuitem){List<MyStaticDBHelper.MyDBParameter> paras = new List<MyStaticDBHelper.MyDBParameter> {new MyStaticDBHelper.MyDBParameter("@MenuItemName", DbType.String, usermenuitem.MENUITEMNAME),new MyStaticDBHelper.MyDBParameter("@MenuID", DbType.Int32, usermenuitem.MENUID),new MyStaticDBHelper.MyDBParameter("@Ordinal", DbType.Int32, usermenuitem.ORDINAL),new MyStaticDBHelper.MyDBParameter("@MenuItemID", DbType.Int32, usermenuitem.MENUITEMID)};string strSQL = "UPDATE [UserMenuItem] SET [MenuItemName] = @MenuItemName, [MenuID] = @MenuID, [Ordinal] = @Ordinal WHERE [MenuItemID] = @MenuItemID";int result = 0;result = MyStaticDBHelper.ExecuteNonQuery(conn, System.Data.CommandType.Text, strSQL, paras);return result;}public int AddUserMenuItem(Object conn, UserMenuItem usermenuitem){List<MyStaticDBHelper.MyDBParameter> paras = new List<MyStaticDBHelper.MyDBParameter> {new MyStaticDBHelper.MyDBParameter("@MenuItemName", DbType.String, usermenuitem.MENUITEMNAME),new MyStaticDBHelper.MyDBParameter("@MenuID", DbType.Int32, usermenuitem.MENUID),new MyStaticDBHelper.MyDBParameter("@Ordinal", DbType.Int32, usermenuitem.ORDINAL),new MyStaticDBHelper.MyDBParameter("@MenuItemID", DbType.Int32, usermenuitem.MENUITEMID)};string strSQL = "INSERT INTO [UserMenuItem] ( [MenuItemName] , [MenuID] , [Ordinal] ) VALUES( @MenuItemName, @MenuID, @Ordinal ); SELECT SCOPE_IDENTITY() as [MenuItemID]";int result = 0;DataSet ds = null;ds = MyStaticDBHelper.ExecuteDataset(conn, System.Data.CommandType.Text, strSQL, paras);if (ds.Tables.Count > 0 && ds.Tables[0].Rows.Count > 0){usermenuitem.MENUITEMID = Convert.ToInt32(ds.Tables[0].Rows[0][0]);result = 1;}return result;}public List<UserMenuItem> GetAllUserMenuItem(Object conn){string strSQL = "SELECT * FROM [UserMenuItem] ";DataSet ds = null;ds = MyStaticDBHelper.ExecuteDataset(conn, System.Data.CommandType.Text, strSQL);return DataMapper.MapDataTableToObjectList<UserMenuItem>(ds.Tables[0]);}public UserMenuItem FindAUserMenuItem(Object conn, UserMenuItem usermenuitem){List<MyStaticDBHelper.MyDBParameter> paras = new List<MyStaticDBHelper.MyDBParameter> {new MyStaticDBHelper.MyDBParameter("@MenuItemID", DbType.Int32, usermenuitem.MENUITEMID)};string strSQL = "SELECT * FROM [UserMenuItem] WHERE [MenuItemID] = @MenuItemID";DataSet ds = null;ds = MyStaticDBHelper.ExecuteDataset(conn, System.Data.CommandType.Text, strSQL, paras);return DataMapper.MapDataTableToSingleRow<UserMenuItem>(ds.Tables[0]);}public System.Int32 SelectCountUserMenuItem(Object conn){string strSQL = "SELECT COUNT(1) AS Count FROM [UserMenuItem] ";Object obj = null;obj = MyStaticDBHelper.ExecuteScalar(conn, System.Data.CommandType.Text, strSQL);return (System.Int32)obj;}public System.Int32 SelectCountWhereClauseUserMenuItem(Object conn, UserMenuItem usermenuitem){List<MyStaticDBHelper.MyDBParameter> paras = new List<MyStaticDBHelper.MyDBParameter> {new MyStaticDBHelper.MyDBParameter("@MenuItemID", DbType.Int32, usermenuitem.MENUITEMID)};string strSQL = "SELECT COUNT(1) AS Count FROM [UserMenuItem] WHERE [MenuItemID] = @MenuItemID";Object obj = null;obj = MyStaticDBHelper.ExecuteScalar(conn, System.Data.CommandType.Text, strSQL, paras);return (System.Int32)obj;}public List<UserMenuItem> SelectTopUserMenuItem(Object conn){string strSQL = "SELECT Top 50 * FROM [UserMenuItem] ";DataSet ds = null;ds = MyStaticDBHelper.ExecuteDataset(conn, System.Data.CommandType.Text, strSQL);return DataMapper.MapDataTableToObjectList<UserMenuItem>(ds.Tables[0]);}public List<UserMenuItem> SelectOrderByPrimaryKeyUserMenuItem(Object conn){string strSQL = "SELECT * FROM [UserMenuItem] ORDER BY [MenuItemID] , [MenuItemName] , [MenuID] , [Ordinal]";DataSet ds = null;ds = MyStaticDBHelper.ExecuteDataset(conn, System.Data.CommandType.Text, strSQL);return DataMapper.MapDataTableToObjectList<UserMenuItem>(ds.Tables[0]);}public List<UserMenuItem> SelectGroupByPrimaryKeyUserMenuItem(Object conn){string strSQL = "SELECT * FROM [UserMenuItem] GROUP BY [MenuItemID] , [MenuItemName] , [MenuID] , [Ordinal]";DataSet ds = null;ds = MyStaticDBHelper.ExecuteDataset(conn, System.Data.CommandType.Text, strSQL);return DataMapper.MapDataTableToObjectList<UserMenuItem>(ds.Tables[0]);}public List<UserMenuItem> SelectUserMenuItemsByMenuID(Object conn, UserMenuItem usermenuitem){List<MyStaticDBHelper.MyDBParameter> paras = new List<MyStaticDBHelper.MyDBParameter> {new MyStaticDBHelper.MyDBParameter("@MenuID", DbType.Int32, usermenuitem.MENUID)};string strSQL = "SELECT * FROM [UserMenuItem] WHERE [MenuID] = @MenuID ORDER BY [Ordinal]";DataSet ds = null;ds = MyStaticDBHelper.ExecuteDataset(conn, System.Data.CommandType.Text, strSQL, paras);return DataMapper.MapDataTableToObjectList<UserMenuItem>(ds.Tables[0]);}public UserMenuItem SelectPreviousMenuItem(Object conn, UserMenuItem usermenuitem){List<MyStaticDBHelper.MyDBParameter> paras = new List<MyStaticDBHelper.MyDBParameter> {new MyStaticDBHelper.MyDBParameter("@MenuID", DbType.Int32, usermenuitem.MENUID),new MyStaticDBHelper.MyDBParameter("@Ordinal", DbType.Int32, usermenuitem.ORDINAL)};string strSQL = "SELECT TOP 1 * FROM [UserMenuItem] WHERE [MenuID] = @MenuID AND [Ordinal] < @Ordinal ORDER BY [Ordinal] DESC";DataSet ds = null;ds = MyStaticDBHelper.ExecuteDataset(conn, System.Data.CommandType.Text, strSQL, paras);return DataMapper.MapDataTableToSingleRow<UserMenuItem>(ds.Tables[0]);}public UserMenuItem SelectNextMenuItem(Object conn, UserMenuItem usermenuitem){List<MyStaticDBHelper.MyDBParameter> paras = new List<MyStaticDBHelper.MyDBParameter> {new MyStaticDBHelper.MyDBParameter("@MenuID", DbType.Int32, usermenuitem.MENUID),new MyStaticDBHelper.MyDBParameter("@Ordinal", DbType.Int32, usermenuitem.ORDINAL)};string strSQL = "SELECT TOP 1 * FROM [UserMenuItem] WHERE [MenuID] = @MenuID AND [Ordinal] > @Ordinal ORDER BY [Ordinal] ASC";DataSet ds = null;ds = MyStaticDBHelper.ExecuteDataset(conn, System.Data.CommandType.Text, strSQL, paras);return DataMapper.MapDataTableToSingleRow<UserMenuItem>(ds.Tables[0]);}public int MoveLeftMenuItem(Object conn, UserMenuItem usermenuitem){List<MyStaticDBHelper.MyDBParameter> paras = new List<MyStaticDBHelper.MyDBParameter> {new MyStaticDBHelper.MyDBParameter("@MenuItemID", DbType.Int32, usermenuitem.MENUITEMID)};string strSQL = "UPDATE [UserMenuItem] SET [Indent] = CASE WHEN [Indent] - 1 >= 0 THEN [Indent] - 1 ELSE 0 END WHERE [MenuItemID] = @MenuItemID";int iResult = 0;iResult = MyStaticDBHelper.ExecuteNonQuery(conn, System.Data.CommandType.Text, strSQL, paras);return iResult;}public int MoveRightMenuItem(Object conn, UserMenuItem usermenuitem){List<MyStaticDBHelper.MyDBParameter> paras = new List<MyStaticDBHelper.MyDBParameter> {new MyStaticDBHelper.MyDBParameter("@MenuItemID", DbType.Int32, usermenuitem.MENUITEMID)};string strSQL = "UPDATE [UserMenuItem] SET [Indent] = CASE WHEN [Indent] + 1 <= 2 THEN [Indent] + 1 ELSE 2 END WHERE [MenuItemID] = @MenuItemID";int iResult = 0;iResult = MyStaticDBHelper.ExecuteNonQuery(conn, System.Data.CommandType.Text, strSQL, paras);return iResult;}public UserMenuItem SelectMaxOrdinal(Object conn, UserMenuItem usermenuitem){List<MyStaticDBHelper.MyDBParameter> paras = new List<MyStaticDBHelper.MyDBParameter> {new MyStaticDBHelper.MyDBParameter("@MenuID", DbType.Int32, usermenuitem.MENUID)};string strSQL = "SELECT IsNull(Max(Ordinal),0) as Ordinal FROM [UserMenuItem] WHERE [MenuID] = @MenuID";DataSet ds = null;ds = MyStaticDBHelper.ExecuteDataset(conn, System.Data.CommandType.Text, strSQL, paras);return DataMapper.MapDataTableToSingleRow<UserMenuItem>(ds.Tables[0]);}#endregion} }

這個數據訪問的代碼都是這種方式，開始準備參數。用的都是MyStaticDBHelper.MyDBParameter結構。給出參數名，參數類型，參數值和參數方向（輸入還是輸出）。然后就是一個sql語句，其中有參數。之后是根據查詢的類型，update/delete/insert的就調用db helper的ExecuteNonQuery方法，如果是select一個表的話，調用db helper的ExecuteDataset方法。再之后，就要將返回的值給轉換成對應的返回類型。如一個實體對象或者實體對象列表。這個類里的sql語句都是預先設計好的sql語句，每個sql語句都有參數，然后每個sql查詢都有一個c#方法與之對應。DataMapper.MapDataTableToSingleRow是將DataTable中第一行轉換成一個實體對象。DataMapper.MapDataTableToObjectList是將返回的DataTable轉換成實體類的列表, 即List<實體類>，這里DataMapper類采用了Reflection的方式來進行轉換實體類。雖然不是最快的。在某些情況下也可以接受。我們做過一個實例程序來對比，將DataTable轉成實體類列表，有直接賦值，Emit, Reflection, delegate, Expression tree等不同的方法，經過性能測試，直接賦值是最快的。Emit稍微比直接賦值慢，但是已經很快了。直接賦值寫代碼比較繁瑣。Emit的方法代碼稍微有點復雜，但是運行效率不錯。又比較靈活。是個相當好的方法，Emit和Expresssion Tree的方法有一些缺點，就是很難調試，萬一出現問題會很難找到問題的根源。這里是比較不同方法將DataTable轉成數據實體類的測試代碼:??http://files.cnblogs.com/mikelij/testGenerateEntity.zip, 大家可以下載了去試試，應該說這幾種方法都還不錯。這里的代碼選用了Reflection方法。因為Reflection也沒有慢得很多。Reflection方法的兼容性好。不會出問題。Emit和Express tree方法經常會遇到不兼容類型的問題。而且很難排查問題。

?數據映射的類

using System; using System.Data; using System.Configuration; using System.Collections.Generic; using System.Reflection;namespace DataAccessCommon {public class DataMapper{public static List<TType> MapDataTableToObjectList<TType>(DataTable dt) where TType : new(){List<TType> result = new List<TType>();foreach (DataRow currentRow in dt.Rows){TType ttype = new TType();for (int i = 0; i < dt.Columns.Count; i++){for (int j = 0; j < ttype.GetType().GetProperties().Length; j++){if (dt.Columns[i].ColumnName.ToUpper() == ttype.GetType().GetProperties()[j].Name.ToUpper()){ttype.GetType().GetProperties()[j].SetValue(ttype, currentRow[i], null);break;}}}result.Add(ttype);ttype = new TType();}return result;}public static TType MapDataTableToSingleRow<TType>(DataTable dt) where TType : new(){TType ttype = new TType();if (dt.Rows.Count > 0){DataRow currentRow = dt.Rows[0];for (int i = 0; i < dt.Columns.Count; i++){for (int j = 0; j < ttype.GetType().GetProperties().Length; j++){if (dt.Columns[i].ColumnName.ToUpper() == ttype.GetType().GetProperties()[j].Name.ToUpper()){ttype.GetType().GetProperties()[j].SetValue(ttype, currentRow[i], null);break;}}}}return ttype;}} }

商業類的代碼

商業類的代碼是基于我們OOA/OOD設計出的。比如一個銀行ATM的例子，其業務里有若干名詞，比如銀行戶頭，ATM機等名詞，每個名詞下又有若干屬性，比如銀行帳號，帳號所有者名字，開立日期等，ATM機有ATM機號，地理位置，所屬銀行編號，等等。圍繞著這些名詞，有相關的一些動作。比如取錢，存錢，插卡入ATM機，記錄ATM流水。等等等等。這里已經將名詞的數據屬性放到了數據實體類里。這些數據實體類里就只有那些名詞的數據屬性，沒有那些動作，即一個純數據的類。這里要提到的商業類包含了商業方法的類，這些商業方法就對應著那些動作。比如取錢，就有一個Withdraw方法對應。存錢就就一個Deposite方法對應。這兩個方法都放在一個叫BankAccount的的商業類里面。這里用的銀行的例子，說明這里所用到的設計方法。

使用Unity之類的IOC容器進行policy injection

下面就要說說IOC了，就是說我們設計一個商業類，里面有幾個商業方法。如果讓調用者直接依賴于這個商業類，那么將來有一天要改變這些商業方法時，可能就不得不同時改調用者和商業類。為了避免這種情況，我們可以從商業類提取出一個接口。這個接口只有這些動作的名字，沒有具體具體實現。然后由負責具體實現的商業類來實現這些接口。說了這些東西與IOC有什么關系呢？這樣做正是為了實現IOC打下基礎。要知道象Unity這樣的IOC容器，都是負責創建對象。它負責從接口映射到具體的商業類。當調用者需要創建一個接口的實例，接口本身是不能實例化的，容器會為調用者創建一個實現了該接口商業類的實例。

一個商業接口的例子：

using System; namespace BusinessLogic {[MyDBHandler]public interface IBLLUserMenu{int AddUserMenu(DataEntity.UserMenu usermenu);int DeleteUserMenu(DataEntity.UserMenu usermenu);DataEntity.UserMenu FindAUserMenu(DataEntity.UserMenu usermenu);System.Collections.Generic.List<DataEntity.UserMenu> GetAllUserMenu();int SelectCountUserMenu();int SelectCountWhereClauseUserMenu(DataEntity.UserMenu usermenu);System.Collections.Generic.List<DataEntity.UserMenu> SelectGroupByPrimaryKeyUserMenu();System.Collections.Generic.List<DataEntity.UserMenu> SelectMenusByApplicationID(DataEntity.UserMenu usermenu);System.Collections.Generic.List<DataEntity.UserMenu> SelectOrderByPrimaryKeyUserMenu();System.Collections.Generic.List<DataEntity.UserMenu> SelectTopUserMenu();int UpdateUserMenu(DataEntity.UserMenu usermenu);object CONNECTION { get; set; }DataEntity.UserMenu USERMENU { get; set; }System.Collections.Generic.List<DataEntity.UserMenu> USERMENU_LIST { get; set; }} }

此代碼中的MyDBHandler是一個字定義的attribute, 用于Unity來進行攔截判斷。有這個attribute就攔截，沒有就不攔截。
而相應的商業類就是這樣的：

using System; using System.Collections.Generic; using System.Data; using DataEntity; using DataAccess; using DataAccessCommon; using CommonUtil;namespace BusinessLogic {internal class BLLUserMenu : BusinessLogic.IBLLUserMenu{private readonly DataAccess.DALUserMenu dal = new DataAccess.DALUserMenu();private object conn = null;private UserMenu usermenu;private List<UserMenu> usermenus;public object CONNECTION{get{return conn;}set{conn = value;}}public UserMenu USERMENU{get{return usermenu;}set{usermenu = value;}}public List<UserMenu> USERMENU_LIST{get{return usermenus;}set{usermenus = value;}}#region business logic methodpublic int DeleteUserMenu(UserMenu usermenu){return dal.DeleteUserMenu(conn,usermenu);}public int UpdateUserMenu(UserMenu usermenu){return dal.UpdateUserMenu(conn,usermenu);}public int AddUserMenu(UserMenu usermenu){return dal.AddUserMenu(conn,usermenu);}public List<UserMenu> GetAllUserMenu(){return dal.GetAllUserMenu(conn);}public UserMenu FindAUserMenu(UserMenu usermenu){return dal.FindAUserMenu(conn,usermenu);}public System.Int32 SelectCountUserMenu(){return dal.SelectCountUserMenu(conn);}public System.Int32 SelectCountWhereClauseUserMenu(UserMenu usermenu){return dal.SelectCountWhereClauseUserMenu(conn,usermenu);}public List<UserMenu> SelectTopUserMenu(){return dal.SelectTopUserMenu(conn);}public List<UserMenu> SelectOrderByPrimaryKeyUserMenu(){return dal.SelectOrderByPrimaryKeyUserMenu(conn);}public List<UserMenu> SelectGroupByPrimaryKeyUserMenu(){return dal.SelectGroupByPrimaryKeyUserMenu(conn);}public List<UserMenu> SelectMenusByApplicationID(UserMenu usermenu){return dal.SelectMenusByApplicationID(conn, usermenu);}#endregion} }

目前這個商業類的方法都比較簡單，如果有比較復雜的，可能一個商業方法里需要調用數據訪問的方法好多個，在做一些邏輯判斷。那么這些商業方法就可以變得復雜多了。如這樣的一個商業方法：

public bool MoveUpItem(UserMenuItem usermenuitem){usermenuitem = dal.FindAUserMenuItem(conn, usermenuitem);UserMenuItem previousMenuItem = dal.SelectPreviousMenuItem(conn, usermenuitem);int iTempOrdinal = usermenuitem.Ordinal;usermenuitem.Ordinal = previousMenuItem.Ordinal;previousMenuItem.Ordinal = iTempOrdinal;dal.UpdateUserMenuItem(conn, usermenuitem);dal.UpdateUserMenuItem(conn, previousMenuItem);return true;}

Unity配置信息：

<unity xmlns="http://schemas.microsoft.com/practices/2010/unity"><sectionExtension type="Microsoft.Practices.Unity.InterceptionExtension.Configuration.InterceptionConfigurationExtension, Microsoft.Practices.Unity.Interception.Configuration" /><namespace name="BusinessLogic" /><container name="myContainer"><extension type="Interception" /><register type="BusinessLogic.IBLLApplication, BusinessLogic" mapTo="BusinessLogic.BLLApplication, BusinessLogic"><interceptor name="myinterceptor" type="InterfaceInterceptor" isDefaultForType="true" /><policyInjection /></register><register type="BusinessLogic.IBLLDomain, BusinessLogic" mapTo="BusinessLogic.BLLDomain, BusinessLogic"><interceptor name="myinterceptor" type="InterfaceInterceptor" isDefaultForType="true" /><policyInjection /></register><register type="BusinessLogic.IBLLFormElement, BusinessLogic" mapTo="BusinessLogic.BLLFormElement, BusinessLogic"><interceptor name="myinterceptor" type="InterfaceInterceptor" isDefaultForType="true" /><policyInjection /></register><register type="BusinessLogic.IBLLUserAccount, BusinessLogic" mapTo="BusinessLogic.BLLUserAccount, BusinessLogic"><interceptor name="myinterceptor" type="InterfaceInterceptor" isDefaultForType="true" /><policyInjection /></register><register type="BusinessLogic.IBLLUserColumns, BusinessLogic" mapTo="BusinessLogic.BLLUserColumns, BusinessLogic"><interceptor name="myinterceptor" type="InterfaceInterceptor" isDefaultForType="true" /><policyInjection /></register><register type="BusinessLogic.IBLLUserForm, BusinessLogic" mapTo="BusinessLogic.BLLUserForm, BusinessLogic"><interceptor name="myinterceptor" type="InterfaceInterceptor" isDefaultForType="true" /><policyInjection /></register><register type="BusinessLogic.IBLLUserMenu, BusinessLogic" mapTo="BusinessLogic.BLLUserMenu, BusinessLogic"><interceptor name="myinterceptor" type="InterfaceInterceptor" isDefaultForType="true" /><policyInjection /></register><register type="BusinessLogic.IBLLUserMenuItem, BusinessLogic" mapTo="BusinessLogic.BLLUserMenuItem, BusinessLogic"><interceptor name="myinterceptor" type="InterfaceInterceptor" isDefaultForType="true" /><policyInjection /></register><register type="BusinessLogic.IBLLUserSession, BusinessLogic" mapTo="BusinessLogic.BLLUserSession, BusinessLogic"><interceptor name="myinterceptor" type="InterfaceInterceptor" isDefaultForType="true" /><policyInjection /></register><register type="BusinessLogic.IBLLUserTables, BusinessLogic" mapTo="BusinessLogic.BLLUserTables, BusinessLogic"><interceptor name="myinterceptor" type="InterfaceInterceptor" isDefaultForType="true" /><policyInjection /></register><interception><policy name="mypolicy"><callHandler name="myHandler1" type="BusinessLogic.MyDBHandler, BusinessLogic"></callHandler><matchingRule name="myrule" type="CustomAttributeMatchingRule"><constructor><param name="attributeType" type="System.Type, mscorlib"><value value="BusinessLogic.MyDBHandlerAttribute, BusinessLogic" typeConverter="BusinessLogic.GetTypeConverter, BusinessLogic" /></param><param name="inherited" type="bool"><value value="true" /></param></constructor></matchingRule></policy></interception></container></unity>

注意到這些register的節點沒有？這些節點實現了接口到具體商業類的映射。接口表示的是一個抽象。它只有方法的聲明，沒有具體實現。在調用者需要一個具體的實現了這個接口的商業類時，容器幫助我們創建這個商業類的實例，而接口到商業類的映射就是在Unity配置文件里做的。
Unity除了幫助我們實現接口到商業類的映射，還可以幫助我們實現aop. 比如log, db transaction, exception handling.

using System; using System.Data; using System.Data.Common; using System.Collections.Generic; using Microsoft.Practices.Unity.InterceptionExtension; using DataAccessCommon; using CommonUtil;namespace BusinessLogic {public class MyDBHandler : ICallHandler{private int iOrder = 0;public IMethodReturn Invoke(IMethodInvocation input, GetNextHandlerDelegate getNext){var retvalue = getNext()(input, getNext); // call the intercepting methodif (retvalue.Exception != null){SysLog.GetInstance().LogError(retvalue.Exception);}return retvalue;}public int Order{get{return iOrder;}set{iOrder = value;}}} }

這個MyDBHandler已經在之前的Unity配置中指定了。即這句：

<callHandler name="myHandler1" type="BusinessLogic.MyDBHandler, BusinessLogic"></callHandler>

這句是去調用被攔截的方法：

retvalue = getNext()(input, getNext);

被攔截方法（即我們的商業方法）返回以后，程序就檢查retvalue.Exception有沒有出錯，有就調用logging的類來寫log。將出錯信息完整地打印出來。
自定義的attribute類：

using System; using System.Collections.Generic; using Microsoft.Practices.Unity; using Microsoft.Practices.Unity.InterceptionExtension; namespace BusinessLogic {public class MyDBHandlerAttribute : HandlerAttribute{public override ICallHandler CreateHandler(IUnityContainer container){return new MyDBHandler();}} }

至于db transaction, 如果數據庫事務比較簡單，可以用TransactionScope，前面的MyDBHandler的invoke方法就替換成這樣。

using (TransactionScope ts = new TransactionScope()){var retvalue = getNext().Invoke(input, getNext);if (retvalue.Exception != null){SysLog.GetInstance().LogError(retvalue.Exception);}else{ts.Complete();}return retvalue}

Unity配置里用到的一個工具類代碼：

using System; using System.Collections.Generic; using Microsoft.Practices.Unity; using Microsoft.Practices.Unity.InterceptionExtension; namespace BusinessLogic {public class GetTypeConverter : System.ComponentModel.TypeConverter{public override object ConvertFrom(System.ComponentModel.ITypeDescriptorContext context,System.Globalization.CultureInfo culture,object value){return Type.GetType(value.ToString());}} }

這個類用來做類型轉換的。用來幫助Unity來找自定義的MyDBHandlerAttribute的。

商業類的調用者

為了調用商業類，我們有一個類來幫助創建相應的商業類的實例：

using System; using System.Collections.Generic; using Microsoft.Practices.Unity; using Microsoft.Practices.Unity.Configuration;namespace BusinessLogic {public static class BusinessClassCreator{public static IUnityContainer container = new UnityContainer().LoadConfiguration("myContainer");public static T GetInstance<T>(){return (T)container.Resolve(typeof(T), null);}public static object GetInstance(Type type){return container.Resolve(type, null);}} }

在調用的地方代碼這么寫：

[HttpGet]public ActionResult SaveMenuScheme(){UserMenu userMenu = new UserMenu();userMenu.MenuID = GetMenuID(this);userMenu = BusinessClassCreator.GetInstance<IBLLUserMenu>().FindAUserMenu(userMenu);short bMenuScheme = 0;bMenuScheme = (short)DesignTableController.GetID(this);userMenu.Scheme = bMenuScheme;BusinessClassCreator.GetInstance<IBLLUserMenu>().UpdateUserMenu(userMenu);return DisplayMenuList();}

這是一個在asp.net mvc中調用上述商業類的樣例代碼，首先通過BusinessClassCreator.GetInstance<IBLLUserMenu>()得到接口IBLLUserMenu對應的商業類對象，然后再調用IBLLUserMenu接口上的方法。比如此例中調用了FindUserMenu方法和UpdateUserMenu方法。每個方法的返回類型已經由接口定義好。我們只要按照這個接口的定義來使用這個接口就可以了。接口在這里的好處就是它定義了商業類的規范，所有實現此接口的商業類都符合此接口的規范。而且具體實現和接口定義是分離的。這樣我們就可以單獨改變實現接口的商業類。商業類的調用者既可以是一個asp.net mvc的程序，也可以是一個asp.net web form的，還可以是一個winform程序。

?demo代碼下載： http://dl.vmall.com/c08haaatpu， 博客園這里上傳不了。沒有辦法。只能選別處了。

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