实战分层架构

现在可选的框架

    现在我们开发一个.net应用，面临的选择比较多。我们可以选择entity framework, enterprise library, nhibernate, 还有一个mybatis.net, 即java世界mybatis/ibatis的.net版。 IOC的框架可以选择Unity, Ninject，Spring.net(java的spring对应的.net版本)。Entity framework可以使用linq查询，有好几种开发模式，如code first, db first, 可以不用写sql。Entity framework适合sql server。虽有mysql提供了entity framework的provider，但是不是很好, 经常不得不单独写sql来操作mysql. Enterprise library是个不错的选择，有log, exception, policy injection的一些东西，操作数据库也比较好。nhibernate是java版hibernate的.net对应版本。对数据库包装得比较多，可以不用写sql. 但是有些时候对数据库操作不够优化，会有一些多余数据库操作。带来一些性能的影响。mybatis.net是个介于ado.net与nhibernate之间的框架，它负责数据库对象与内存对象的映射。程序员必须写sql语句来操作数据库。IOC的框架中Unity, Ninject, Spring.net, 都是不错的框架。有时这些框架能照顾到我们大部分的需求，也有一些情况，不能全部照顾到我们的需求。这时就得用一些老办法。比如直接就用ado.net

适应多种数据库的db helper代码

    这里主要是想说一些基于ado.net来开发asp.net mvc应用的一些思路。为什么选用ado.net呢，ado.net性能可以达到最好，灵活。先看一段db helper的代码:

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();}}
}

此代码能支持访问Oracle, sql server, OleDB。用的都是DbConnection之类的。只要开始选择了正确的provider, DbProviderFactories就给创建相应的connection, command等类，就可以顺利地处理这个对应的数据库了。sql的参数是DbType。用来适应数据库类型。MyDBParameter结构封装了参数名，类型，参数值，传入传出方向。目前的版本只考虑了一个数据库连接。连接串只有一个。DbProviderFactory只有一个实例。没有考虑到动态切换连接的情况。如果是要多个连接，得要多个DbProviderFactory的实例。CreateCommand方法里判断了传入的的数据库连接是一个DbConnection还是一个DbTransaction，如果是一个DbTransaction的话，可以加入这个数据库事务。如果只是一个DbConnection则不加入已有的数据库事务，使用自动的数据库事务。

数据实体类

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}
}

纯数据的类。这里使用了比较老的c#语法。也可以加上DataAnnotation的标签。可以实现验证数据，也可以加上Display标签，引用资源文件。这个数据实体类在MVC页面里绑定时可以显示想应的label。label的内容来自于资源文件，便于使用多语言的界面。

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}
}

 

下面是数据访问的代码:

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}
}

这个数据访问的代码都是这种方式，开始准备参数。用的都是MyStaticDBHelper.MyDBParameter结构。给出参数名，参数类型，参数值和参数方向（输入还是输出）。然后就是一个sql语句，其中有参数。之后是根据查询的类型，update/delete/insert的就调用db helper的ExecuteNonQuery方法，如果是select一个表的话，调用db helper的ExecuteDataset方法。再之后，就要将返回的值给转换成对应的返回类型。如一个实体对象或者实体对象列表。这个类里的sql语句都是预先设计好的sql语句，每个sql语句都有参数，然后每个sql查询都有一个c#方法与之对应。DataMapper.MapDataTableToSingleRow是将DataTable中第一行转换成一个实体对象。DataMapper.MapDataTableToObjectList是将返回的DataTable转换成实体类的列表, 即List<实体类>，这里DataMapper类采用了Reflection的方式来进行转换实体类。虽然不是最快的。在某些情况下也可以接受。我们做过一个实例程序来对比，将DataTable转成实体类列表，有直接赋值，Emit, Reflection, delegate, Expression tree等不同的方法，经过性能测试，直接赋值是最快的。Emit稍微比直接赋值慢，但是已经很快了。直接赋值写代码比较繁琐。Emit的方法代码稍微有点复杂，但是运行效率不错。又比较灵活。是个相当好的方法，Emit和Expresssion Tree的方法有一些缺点，就是很难调试，万一出现问题会很难找到问题的根源。这里是比较不同方法将DataTable转成数据实体类的测试代码:  http://files.cnblogs.com/mikelij/testGenerateEntity.zip, 大家可以下载了去试试，应该说这几种方法都还不错。这里的代码选用了Reflection方法。因为Reflection也没有慢得很多。Reflection方法的兼容性好。不会出问题。Emit和Express tree方法经常会遇到不兼容类型的问题。而且很难排查问题。

 数据映射的类

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;}}
}

商业类的代码

商业类的代码是基于我们OOA/OOD设计出的。比如一个银行ATM的例子，其业务里有若干名词，比如银行户头，ATM机等名词，每个名词下又有若干属性，比如银行帐号，帐号所有者名字，开立日期等，ATM机有ATM机号，地理位置，所属银行编号，等等。围绕着这些名词，有相关的一些动作。比如取钱，存钱，插卡入ATM机，记录ATM流水。等等等等。这里已经将名词的数据属性放到了数据实体类里。这些数据实体类里就只有那些名词的数据属性，没有那些动作，即一个纯数据的类。这里要提到的商业类包含了商业方法的类，这些商业方法就对应着那些动作。比如取钱，就有一个Withdraw方法对应。存钱就就一个Deposite方法对应。这两个方法都放在一个叫BankAccount的的商业类里面。这里用的银行的例子，说明这里所用到的设计方法。

使用Unity之类的IOC容器进行policy injection

下面就要说说IOC了，就是说我们设计一个商业类，里面有几个商业方法。如果让调用者直接依赖于这个商业类，那么将来有一天要改变这些商业方法时，可能就不得不同时改调用者和商业类。为了避免这种情况，我们可以从商业类提取出一个接口。这个接口只有这些动作的名字，没有具体具体实现。然后由负责具体实现的商业类来实现这些接口。说了这些东西与IOC有什么关系呢？这样做正是为了实现IOC打下基础。要知道象Unity这样的IOC容器，都是负责创建对象。它负责从接口映射到具体的商业类。当调用者需要创建一个接口的实例，接口本身是不能实例化的，容器会为调用者创建一个实现了该接口商业类的实例。

一个商业接口的例子：

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; }}
}

此代码中的MyDBHandler是一个字定义的attribute, 用于Unity来进行拦截判断。有这个attribute就拦截，没有就不拦截。
而相应的商业类就是这样的：

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}
}

目前这个商业类的方法都比较简单，如果有比较复杂的，可能一个商业方法里需要调用数据访问的方法好多个，在做一些逻辑判断。那么这些商业方法就可以变得复杂多了。如这样的一个商业方法：

        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>

注意到这些register的节点没有？这些节点实现了接口到具体商业类的映射。接口表示的是一个抽象。它只有方法的声明，没有具体实现。在调用者需要一个具体的实现了这个接口的商业类时，容器帮助我们创建这个商业类的实例，而接口到商业类的映射就是在Unity配置文件里做的。
Unity除了帮助我们实现接口到商业类的映射，还可以帮助我们实现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;}}}
}

这个MyDBHandler已经在之前的Unity配置中指定了。即这句：

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

这句是去调用被拦截的方法：

retvalue = getNext()(input, getNext);

被拦截方法（即我们的商业方法）返回以后，程序就检查retvalue.Exception有没有出错，有就调用logging的类来写log。将出错信息完整地打印出来。
自定义的attribute类：

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, 如果数据库事务比较简单，可以用TransactionScope，前面的MyDBHandler的invoke方法就替换成这样。

                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配置里用到的一个工具类代码：

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());}}
}

这个类用来做类型转换的。用来帮助Unity来找自定义的MyDBHandlerAttribute的。

商业类的调用者

为了调用商业类，我们有一个类来帮助创建相应的商业类的实例：

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);}}
}

在调用的地方代码这么写：

        [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();}

这是一个在asp.net mvc中调用上述商业类的样例代码，首先通过BusinessClassCreator.GetInstance<IBLLUserMenu>()得到接口IBLLUserMenu对应的商业类对象，然后再调用IBLLUserMenu接口上的方法。比如此例中调用了FindUserMenu方法和UpdateUserMenu方法。每个方法的返回类型已经由接口定义好。我们只要按照这个接口的定义来使用这个接口就可以了。接口在这里的好处就是它定义了商业类的规范，所有实现此接口的商业类都符合此接口的规范。而且具体实现和接口定义是分离的。这样我们就可以单独改变实现接口的商业类。商业类的调用者既可以是一个asp.net mvc的程序，也可以是一个asp.net web form的，还可以是一个winform程序。

 demo代码下载： http://dl.vmall.com/c08haaatpu， 博客园这里上传不了。没有办法。只能选别处了。