23、ASP.NET MVC入门到精通——业务层和数据层父类及接口-T4模板

本系列目录：ASP.NET MVC4入门到精通系列目录汇总

在上一篇中，我们已经把项目的基本框架搭起来了，这一篇我们就来实现业务层和数据层的父接口及父类。

1、我们先来定义一个业务层父接口IBaseBLL.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using System.Text;
using System.Threading.Tasks;

namespace IBLL
{
    /// <summary>
    /// 业务父 接口
    /// </summary>
    /// <typeparam name="T"></typeparam>
    public interface IBaseBLL<T> where T:class,new()
    {
        //定义 增删改查 方法
        #region 1.0 新增 实体 +int Add(T model)
        /// <summary>
        /// 新增 实体
        /// </summary>
        /// <param name="model"></param>
        /// <returns></returns>
        int Add(T model);
        #endregion

        #region 2.0 根据 id 删除 +int Del(T model)
        /// <summary>
        /// 根据 id 删除
        /// </summary>
        /// <param name="model">包含要删除id的对象</param>
        /// <returns></returns>
        int Del(T model);
        #endregion

        #region 3.0 根据条件删除 +int DelBy(Expression<Func<T, bool>> delWhere)
        /// <summary>
        /// 3.0 根据条件删除
        /// </summary>
        /// <param name="delWhere"></param>
        /// <returns></returns>
        int DelBy(Expression<Func<T, bool>> delWhere);
        #endregion

        #region 4.0 修改 +int Modify(T model, params string[] proNames)
        /// <summary>
        /// 4.0 修改，如：
        /// T u = new T() { uId = 1, uLoginName = "asdfasdf" };
        /// this.Modify(u, "uLoginName");
        /// </summary>
        /// <param name="model">要修改的实体对象</param>
        /// <param name="proNames">要修改的 属性 名称</param>
        /// <returns></returns>
        int Modify(T model, params string[] proNames);
        #endregion

        #region 4.0 批量修改 +int Modify(T model, Expression<Func<T, bool>> whereLambda, params string[] modifiedProNames)
        /// <summary>
        /// 4.0 批量修改
        /// </summary>
        /// <param name="model">要修改的实体对象</param>
        /// <param name="whereLambda">查询条件</param>
        /// <param name="proNames">要修改的 属性 名称</param>
        /// <returns></returns>
        int ModifyBy(T model, Expression<Func<T, bool>> whereLambda, params string[] modifiedProNames);
        #endregion

        #region 5.0 根据条件查询 +List<T> GetListBy(Expression<Func<T,bool>> whereLambda)
        /// <summary>
        /// 5.0 根据条件查询 +List<T> GetListBy(Expression<Func<T,bool>> whereLambda)
        /// </summary>
        /// <param name="whereLambda"></param>
        /// <returns></returns>
        List<T> GetListBy(Expression<Func<T, bool>> whereLambda);
        #endregion

        #region 5.1 根据条件 排序 和查询 + List<T> GetListBy<TKey>
        /// <summary>
        /// 5.1 根据条件 排序 和查询
        /// </summary>
        /// <typeparam name="TKey">排序字段类型</typeparam>
        /// <param name="whereLambda">查询条件 lambda表达式</param>
        /// <param name="orderLambda">排序条件 lambda表达式</param>
        /// <returns></returns>
        List<T> GetListBy<TKey>(Expression<Func<T, bool>> whereLambda, Expression<Func<T, TKey>> orderLambda);
        #endregion

        #region 6.0 分页查询 + List<T> GetPagedList<TKey>
        /// <summary>
        /// 6.0 分页查询 + List<T> GetPagedList<TKey>
        /// </summary>
        /// <param name="pageIndex">页码</param>
        /// <param name="pageSize">页容量</param>
        /// <param name="whereLambda">条件 lambda表达式</param>
        /// <param name="orderBy">排序 lambda表达式</param>
        /// <returns></returns>
        List<T> GetPagedList<TKey>(int pageIndex, int pageSize, Expression<Func<T, bool>> whereLambda, Expression<Func<T, TKey>> orderBy);
        #endregion
    }
}

2、定义一个数据层父接口IBaseDAL.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using System.Text;
using System.Threading.Tasks;

namespace IDAL
{
    /// <summary>
    /// 数据层父接口
    /// </summary>
   public interface IBaseDAL<T> where T:class ,new()
    {
        //定义增删改查方法
        #region 1.0 新增 实体 +int Add(T model)
        /// <summary>
        /// 新增 实体
        /// </summary>
        /// <param name="model"></param>
        /// <returns></returns>
        int Add(T model);
        #endregion

        #region 2.0 根据 id 删除 +int Del(T model)
        /// <summary>
        /// 根据 id 删除
        /// </summary>
        /// <param name="model">包含要删除id的对象</param>
        /// <returns></returns>
        int Del(T model);
        #endregion

        #region 3.0 根据条件删除 +int DelBy(Expression<Func<T, bool>> delWhere)
        /// <summary>
        /// 3.0 根据条件删除
        /// </summary>
        /// <param name="delWhere"></param>
        /// <returns></returns>
        int DelBy(Expression<Func<T, bool>> delWhere);
        #endregion

        #region 4.0 修改 +int Modify(T model, params string[] proNames)
        /// <summary>
        /// 4.0 修改，如：
        /// T u = new T() { uId = 1, uLoginName = "asdfasdf" };
        /// this.Modify(u, "uLoginName");
        /// </summary>
        /// <param name="model">要修改的实体对象</param>
        /// <param name="proNames">要修改的 属性 名称</param>
        /// <returns></returns>
        int Modify(T model, params string[] proNames);
        #endregion

        #region 4.0 批量修改 +int Modify(T model, Expression<Func<T, bool>> whereLambda, params string[] modifiedProNames)
        /// <summary>
        /// 4.0 批量修改
        /// </summary>
        /// <param name="model">要修改的实体对象</param>
        /// <param name="whereLambda">查询条件</param>
        /// <param name="proNames">要修改的 属性 名称</param>
        /// <returns></returns>
        int ModifyBy(T model, Expression<Func<T, bool>> whereLambda, params string[] modifiedProNames);
        #endregion

        #region 5.0 根据条件查询 +List<T> GetListBy(Expression<Func<T,bool>> whereLambda)
        /// <summary>
        /// 5.0 根据条件查询 +List<T> GetListBy(Expression<Func<T,bool>> whereLambda)
        /// </summary>
        /// <param name="whereLambda"></param>
        /// <returns></returns>
        List<T> GetListBy(Expression<Func<T, bool>> whereLambda);
        #endregion

        #region 5.1 根据条件 排序 和查询 + List<T> GetListBy<TKey>
        /// <summary>
        /// 5.1 根据条件 排序 和查询
        /// </summary>
        /// <typeparam name="TKey">排序字段类型</typeparam>
        /// <param name="whereLambda">查询条件 lambda表达式</param>
        /// <param name="orderLambda">排序条件 lambda表达式</param>
        /// <returns></returns>
        List<T> GetListBy<TKey>(Expression<Func<T, bool>> whereLambda, Expression<Func<T, TKey>> orderLambda);
        #endregion

        #region 6.0 分页查询 + List<T> GetPagedList<TKey>
        /// <summary>
        /// 6.0 分页查询 + List<T> GetPagedList<TKey>
        /// </summary>
        /// <param name="pageIndex">页码</param>
        /// <param name="pageSize">页容量</param>
        /// <param name="whereLambda">条件 lambda表达式</param>
        /// <param name="orderBy">排序 lambda表达式</param>
        /// <returns></returns>
        List<T> GetPagedList<TKey>(int pageIndex, int pageSize, Expression<Func<T, bool>> whereLambda, Expression<Func<T, TKey>> orderBy);
        #endregion
    }
}

3、我们数据库中有许多的表，通常每一张表都对应一个业务实体，如果我们每一个业务实体类都自己去手写的话，太浪费时间了，我们可以使用T4模板，简化这些枯燥的操作，提高我们的开发效率。

新建一个文本模板

然后把以下代码复制上去，

<#@ template language="C#" debug="false" hostspecific="true"#>
<#@ include file="EF.Utility.CS.ttinclude"#><#@ output extension=".cs"#>
<#
CodeGenerationTools code = new CodeGenerationTools(this);
MetadataLoader loader = new MetadataLoader(this);
CodeRegion region = new CodeRegion(this, );
MetadataTools ef = new MetadataTools(this);
string inputFile = @"..\MODEL\OA.edmx";
EdmItemCollection ItemCollection = loader.CreateEdmItemCollection(inputFile);
string namespaceName = code.VsNamespaceSuggestion();
EntityFrameworkTemplateFileManager fileManager = EntityFrameworkTemplateFileManager.Create(this);
#>
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace IBLL
{
<#

// Emit Entity Types
foreach (EntityType entity in ItemCollection.GetItems<EntityType>().OrderBy(e => e.Name))
{
    //fileManager.StartNewFile(entity.Name + "RepositoryExt.cs");
    //BeginNamespace(namespaceName, code);

#>
    public partial interface I<#=entity.Name#>BLL : IBaseBLL<Model.<#=entity.Name#>>
    {
    }

<#}#>

}

当然，你也可以使用NuGet安装tangibleT4EditorPlusModellingToolsVS2012，安装完成后，按照如下的方式添加T4模板

按Ctrl+S自动生成代码，自动生成的IBLL.cs如下：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace IBLL
{
    public partial interface IBill_LeaveBLL : IBaseBLL<Model.Bill_Leave>
    {
    }

    public partial interface IoldWF_AutoTransactNodeBLL : IBaseBLL<Model.oldWF_AutoTransactNode>
    {
    }

    public partial interface IoldWF_BillFlowNodeBLL : IBaseBLL<Model.oldWF_BillFlowNode>
    {
    }

    public partial interface IoldWF_BillFlowNodeRemarkBLL : IBaseBLL<Model.oldWF_BillFlowNodeRemark>
    {
    }

    public partial interface IoldWF_BillStateBLL : IBaseBLL<Model.oldWF_BillState>
    {
    }

    public partial interface IoldWF_NodeBLL : IBaseBLL<Model.oldWF_Node>
    {
    }

    public partial interface IoldWF_NodeStateBLL : IBaseBLL<Model.oldWF_NodeState>
    {
    }

    public partial interface IoldWF_WorkFlowBLL : IBaseBLL<Model.oldWF_WorkFlow>
    {
    }

    public partial interface IoldWF_WorkFlowNodeBLL : IBaseBLL<Model.oldWF_WorkFlowNode>
    {
    }

    public partial interface IOu_DepartmentBLL : IBaseBLL<Model.Ou_Department>
    {
    }

    public partial interface IOu_PermissionBLL : IBaseBLL<Model.Ou_Permission>
    {
    }

    public partial interface IOu_RoleBLL : IBaseBLL<Model.Ou_Role>
    {
    }

    public partial interface IOu_RolePermissionBLL : IBaseBLL<Model.Ou_RolePermission>
    {
    }

    public partial interface IOu_UserInfoBLL : IBaseBLL<Model.Ou_UserInfo>
    {
    }

    public partial interface IOu_UserRoleBLL : IBaseBLL<Model.Ou_UserRole>
    {
    }

    public partial interface IOu_UserVipPermissionBLL : IBaseBLL<Model.Ou_UserVipPermission>
    {
    }

    public partial interface IW_WorkFlowBLL : IBaseBLL<Model.W_WorkFlow>
    {
    }

    public partial interface IW_WorkFlowBranchBLL : IBaseBLL<Model.W_WorkFlowBranch>
    {
    }

    public partial interface IW_WorkFlowNodeBLL : IBaseBLL<Model.W_WorkFlowNode>
    {
    }

    public partial interface IW_WrokFlowRoleBLL : IBaseBLL<Model.W_WrokFlowRole>
    {
    }

    public partial interface IWR_WorkFlowApplyBLL : IBaseBLL<Model.WR_WorkFlowApply>
    {
    }

    public partial interface IWR_WrokFlowApplyDetailsBLL : IBaseBLL<Model.WR_WrokFlowApplyDetails>
    {
    }

}

4、把IBLL.tt拷贝到IDAL项目下，然后修改命名空间为IDAL，修改接口声明模板

namespace IDAL
public partial interface I<#=entity.Name#>DAL : IBaseDAL<Model.<#=entity.Name#>>

按Ctrl+S自动生成代码，自动生成的IDAL.cs如下：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace IDAL
{
    public partial interface IBill_LeaveDAL : IBaseDAL<Model.Bill_Leave>
    {
    }

    public partial interface IoldWF_AutoTransactNodeDAL : IBaseDAL<Model.oldWF_AutoTransactNode>
    {
    }

    public partial interface IoldWF_BillFlowNodeDAL : IBaseDAL<Model.oldWF_BillFlowNode>
    {
    }

    public partial interface IoldWF_BillFlowNodeRemarkDAL : IBaseDAL<Model.oldWF_BillFlowNodeRemark>
    {
    }

    public partial interface IoldWF_BillStateDAL : IBaseDAL<Model.oldWF_BillState>
    {
    }

    public partial interface IoldWF_NodeDAL : IBaseDAL<Model.oldWF_Node>
    {
    }

    public partial interface IoldWF_NodeStateDAL : IBaseDAL<Model.oldWF_NodeState>
    {
    }

    public partial interface IoldWF_WorkFlowDAL : IBaseDAL<Model.oldWF_WorkFlow>
    {
    }

    public partial interface IoldWF_WorkFlowNodeDAL : IBaseDAL<Model.oldWF_WorkFlowNode>
    {
    }

    public partial interface IOu_DepartmentDAL : IBaseDAL<Model.Ou_Department>
    {
    }

    public partial interface IOu_PermissionDAL : IBaseDAL<Model.Ou_Permission>
    {
    }

    public partial interface IOu_RoleDAL : IBaseDAL<Model.Ou_Role>
    {
    }

    public partial interface IOu_RolePermissionDAL : IBaseDAL<Model.Ou_RolePermission>
    {
    }

    public partial interface IOu_UserInfoDAL : IBaseDAL<Model.Ou_UserInfo>
    {
    }

    public partial interface IOu_UserRoleDAL : IBaseDAL<Model.Ou_UserRole>
    {
    }

    public partial interface IOu_UserVipPermissionDAL : IBaseDAL<Model.Ou_UserVipPermission>
    {
    }

    public partial interface IW_WorkFlowDAL : IBaseDAL<Model.W_WorkFlow>
    {
    }

    public partial interface IW_WorkFlowBranchDAL : IBaseDAL<Model.W_WorkFlowBranch>
    {
    }

    public partial interface IW_WorkFlowNodeDAL : IBaseDAL<Model.W_WorkFlowNode>
    {
    }

    public partial interface IW_WrokFlowRoleDAL : IBaseDAL<Model.W_WrokFlowRole>
    {
    }

    public partial interface IWR_WorkFlowApplyDAL : IBaseDAL<Model.WR_WorkFlowApply>
    {
    }

    public partial interface IWR_WrokFlowApplyDetailsDAL : IBaseDAL<Model.WR_WrokFlowApplyDetails>
    {
    }

}

注意，我这里生成的所有接口都是partial类型的，这样我以后可以很方便的进行扩展

关于T4模板的使用不在本篇所讲的范畴，有兴趣的朋友，可以查找相关资料学习，我这里只做简要说明。

<#@ include file="EF.Utility.CS.ttinclude"#>：引入微软的生成框架

<#@ output extension=".cs"#>：指定生成的文件类型为.cs文件

string inputFile = @"..\MODEL\OA.edmx"：这里使用相对路径指向我们新建的ADO.NET实体数据模型文件。

5、添加数据层的父类BaseDAL.cs

前面数据层接口和业务层接口都已经添加好了，那么现在来添加数据层类和业务层类

在DAL项目中添加EntityFramework.dll和System.Data.Entity.dll的引用

using System;
using System.Collections.Generic;
using System.Data.Entity;
using System.Data.Entity.Infrastructure;
using System.Linq;
using System.Linq.Expressions;
using System.Reflection;
using System.Text;
using Model;

namespace DAL
{
    /// <summary>
    /// 数据层 父类
    /// </summary>
    /// <typeparam name="T"></typeparam>
    public class BaseDAL<T> : IDAL.IBaseDAL<T> where T : class,new()
    {
        /// <summary>
        /// EF上下文对象
        /// </summary>
        DbContext db = new OAEntities(); //new DBContextFactory().GetDbContext();// 

        #region 1.0 新增 实体 +int Add(T model)
        /// <summary>
        /// 新增 实体
        /// </summary>
        /// <param name="model"></param>
        /// <returns></returns>
        public int Add(T model)
        {
            db.Set<T>().Add(model);
            return db.SaveChanges();//保存成功后，会将自增的id设置给 model的 主键属性，并返回受影响行数
        }
        #endregion

        #region 2.0 根据 id 删除 +int Del(T model)
        /// <summary>
        /// 根据 id 删除
        /// </summary>
        /// <param name="model">包含要删除id的对象</param>
        /// <returns></returns>
        public int Del(T model)
        {
            db.Set<T>().Attach(model);
            db.Set<T>().Remove(model);
            return db.SaveChanges();
        }
        #endregion

        #region 3.0 根据条件删除 +int DelBy(Expression<Func<T, bool>> delWhere)
        /// <summary>
        /// 3.0 根据条件删除
        /// </summary>
        /// <param name="delWhere"></param>
        /// <returns></returns>
        public int DelBy(Expression<Func<T, bool>> delWhere)
        {
            //3.1查询要删除的数据
            List<T> listDeleting = db.Set<T>().Where(delWhere).ToList();
            //3.2将要删除的数据 用删除方法添加到 EF 容器中
            listDeleting.ForEach(u =>
            {
                db.Set<T>().Attach(u);//先附加到 EF容器
                db.Set<T>().Remove(u);//标识为 删除 状态
            });
            //3.3一次性 生成sql语句到数据库执行删除
            return db.SaveChanges();
        }
        #endregion

        #region 4.0 修改 +int Modify(T model, params string[] proNames)
        /// <summary>
        /// 4.0 修改，如：
        /// T u = new T() { uId = 1, uLoginName = "asdfasdf" };
        /// this.Modify(u, "uLoginName");
        /// </summary>
        /// <param name="model">要修改的实体对象</param>
        /// <param name="proNames">要修改的 属性 名称</param>
        /// <returns></returns>
        public int Modify(T model, params string[] proNames)
        {
            //4.1将 对象 添加到 EF中
            DbEntityEntry entry = db.Entry<T>(model);
            //4.2先设置 对象的包装 状态为 Unchanged
            entry.State = System.Data.EntityState.Unchanged;
            //4.3循环 被修改的属性名 数组
            foreach (string proName in proNames)
            {
                //4.4将每个 被修改的属性的状态 设置为已修改状态;后面生成update语句时，就只为已修改的属性 更新
                entry.Property(proName).IsModified = true;
            }
            //4.4一次性 生成sql语句到数据库执行
            return db.SaveChanges();
        }
        #endregion

        #region 4.0 批量修改 +int Modify(T model, Expression<Func<T, bool>> whereLambda, params string[] modifiedProNames)
        /// <summary>
        /// 4.0 批量修改
        /// </summary>
        /// <param name="model">要修改的实体对象</param>
        /// <param name="whereLambda">查询条件</param>
        /// <param name="proNames">要修改的 属性 名称</param>
        /// <returns></returns>
        public int ModifyBy(T model, Expression<Func<T, bool>> whereLambda, params string[] modifiedProNames)
        {
            //4.1查询要修改的数据
            List<T> listModifing = db.Set<T>().Where(whereLambda).ToList();

            //获取 实体类 类型对象
            Type t = typeof(T); // model.GetType();
            //获取 实体类 所有的 公有属性
            List<PropertyInfo> proInfos = t.GetProperties(BindingFlags.Instance | BindingFlags.Public).ToList();
            //创建 实体属性 字典集合
            Dictionary<string, PropertyInfo> dictPros = new Dictionary<string, PropertyInfo>();
            //将 实体属性 中要修改的属性名 添加到 字典集合中 键：属性名  值：属性对象
            proInfos.ForEach(p =>
            {
                if (modifiedProNames.Contains(p.Name))
                {
                    dictPros.Add(p.Name, p);
                }
            });

            //4.3循环 要修改的属性名
            foreach (string proName in modifiedProNames)
            {
                //判断 要修改的属性名是否在 实体类的属性集合中存在
                if (dictPros.ContainsKey(proName))
                {
                    //如果存在，则取出要修改的 属性对象
                    PropertyInfo proInfo = dictPros[proName];
                    //取出 要修改的值
                    object newValue = proInfo.GetValue(model, null); //object newValue = model.uName;

                    //4.4批量设置 要修改 对象的 属性
                    foreach (T usrO in listModifing)
                    {
                        //为 要修改的对象 的 要修改的属性 设置新的值
                        proInfo.SetValue(usrO, newValue, null); //usrO.uName = newValue;
                    }
                }
            }
            //4.4一次性 生成sql语句到数据库执行
            return db.SaveChanges();
        }
        #endregion

        #region 5.0 根据条件查询 +List<T> GetListBy(Expression<Func<T,bool>> whereLambda)
        /// <summary>
        /// 5.0 根据条件查询 +List<T> GetListBy(Expression<Func<T,bool>> whereLambda)
        /// </summary>
        /// <param name="whereLambda"></param>
        /// <returns></returns>
        public List<T> GetListBy(Expression<Func<T, bool>> whereLambda)
        {
            return db.Set<T>().Where(whereLambda).ToList();
        }
        #endregion

        #region 5.1 根据条件 排序 和查询 + List<T> GetListBy<TKey>
        /// <summary>
        /// 5.1 根据条件 排序 和查询
        /// </summary>
        /// <typeparam name="TKey">排序字段类型</typeparam>
        /// <param name="whereLambda">查询条件 lambda表达式</param>
        /// <param name="orderLambda">排序条件 lambda表达式</param>
        /// <returns></returns>
        public List<T> GetListBy<TKey>(Expression<Func<T, bool>> whereLambda, Expression<Func<T, TKey>> orderLambda)
        {
            return db.Set<T>().Where(whereLambda).OrderBy(orderLambda).ToList();
        }
        #endregion

        #region 6.0 分页查询 + List<T> GetPagedList<TKey>
        /// <summary>
        /// 6.0 分页查询 + List<T> GetPagedList<TKey>
        /// </summary>
        /// <param name="pageIndex">页码</param>
        /// <param name="pageSize">页容量</param>
        /// <param name="whereLambda">条件 lambda表达式</param>
        /// <param name="orderBy">排序 lambda表达式</param>
        /// <returns></returns>
        public List<T> GetPagedList<TKey>(int pageIndex, int pageSize, Expression<Func<T, bool>> whereLambda, Expression<Func<T, TKey>> orderBy)
        {
            // 分页 一定注意： Skip 之前一定要 OrderBy
            return db.Set<T>().Where(whereLambda).OrderBy(orderBy).Skip((pageIndex - ) * pageSize).Take(pageSize).ToList();
        }
        #endregion
    }
}

6、拷贝IDAL.tt到DAL项目中，改名为DAL.tt，然后修改T4模板

按Ctrl+S自动生成代码，自动生成的DAL.cs如下：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using IDAL;

namespace DAL
{
    public partial class Bill_LeaveDAL : BaseDAL<Model.Bill_Leave>,IBill_LeaveDAL
    {
    }

    public partial class oldWF_AutoTransactNodeDAL : BaseDAL<Model.oldWF_AutoTransactNode>,IoldWF_AutoTransactNodeDAL
    {
    }

    public partial class oldWF_BillFlowNodeDAL : BaseDAL<Model.oldWF_BillFlowNode>,IoldWF_BillFlowNodeDAL
    {
    }

    public partial class oldWF_BillFlowNodeRemarkDAL : BaseDAL<Model.oldWF_BillFlowNodeRemark>,IoldWF_BillFlowNodeRemarkDAL
    {
    }

    public partial class oldWF_BillStateDAL : BaseDAL<Model.oldWF_BillState>,IoldWF_BillStateDAL
    {
    }

    public partial class oldWF_NodeDAL : BaseDAL<Model.oldWF_Node>,IoldWF_NodeDAL
    {
    }

    public partial class oldWF_NodeStateDAL : BaseDAL<Model.oldWF_NodeState>,IoldWF_NodeStateDAL
    {
    }

    public partial class oldWF_WorkFlowDAL : BaseDAL<Model.oldWF_WorkFlow>,IoldWF_WorkFlowDAL
    {
    }

    public partial class oldWF_WorkFlowNodeDAL : BaseDAL<Model.oldWF_WorkFlowNode>,IoldWF_WorkFlowNodeDAL
    {
    }

    public partial class Ou_DepartmentDAL : BaseDAL<Model.Ou_Department>,IOu_DepartmentDAL
    {
    }

    public partial class Ou_PermissionDAL : BaseDAL<Model.Ou_Permission>,IOu_PermissionDAL
    {
    }

    public partial class Ou_RoleDAL : BaseDAL<Model.Ou_Role>,IOu_RoleDAL
    {
    }

    public partial class Ou_RolePermissionDAL : BaseDAL<Model.Ou_RolePermission>,IOu_RolePermissionDAL
    {
    }

    public partial class Ou_UserInfoDAL : BaseDAL<Model.Ou_UserInfo>,IOu_UserInfoDAL
    {
    }

    public partial class Ou_UserRoleDAL : BaseDAL<Model.Ou_UserRole>,IOu_UserRoleDAL
    {
    }

    public partial class Ou_UserVipPermissionDAL : BaseDAL<Model.Ou_UserVipPermission>,IOu_UserVipPermissionDAL
    {
    }

    public partial class W_WorkFlowDAL : BaseDAL<Model.W_WorkFlow>,IW_WorkFlowDAL
    {
    }

    public partial class W_WorkFlowBranchDAL : BaseDAL<Model.W_WorkFlowBranch>,IW_WorkFlowBranchDAL
    {
    }

    public partial class W_WorkFlowNodeDAL : BaseDAL<Model.W_WorkFlowNode>,IW_WorkFlowNodeDAL
    {
    }

    public partial class W_WrokFlowRoleDAL : BaseDAL<Model.W_WrokFlowRole>,IW_WrokFlowRoleDAL
    {
    }

    public partial class WR_WorkFlowApplyDAL : BaseDAL<Model.WR_WorkFlowApply>,IWR_WorkFlowApplyDAL
    {
    }

    public partial class WR_WrokFlowApplyDetailsDAL : BaseDAL<Model.WR_WrokFlowApplyDetails>,IWR_WrokFlowApplyDetailsDAL
    {
    }

}

7、BLL项目中添加业务层的父类BaseBLL.cs，在业务父类中只能调用数据库父类接口，所以可以通过一个抽象方法，让子类来实现数据库对象的实例化操作。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using System.Text;
using System.Reflection;

namespace BLL
{
    /// <summary>
    /// 业务层父类
    /// </summary>
    /// <typeparam name="T"></typeparam>
    public abstract class BaseBLL<T> : IBLL.IBaseBLL<T> where T : class,new()
    {
        public BaseBLL()
        {
            SetDAL();
        }

        //1.数据层接口 对象 - 等待 被实例化
        protected IDAL.IBaseDAL<T> idal;// = new idal.BaseDAL();
        /// <summary>
        /// 由子类实现，为 业务父类 里的 数据接口对象 设置 值！
        /// </summary>
        public abstract void SetDAL();

        //2.增删改查方法
        #region 1.0 新增 实体 +int Add(T model)
        /// <summary>
        /// 新增 实体
        /// </summary>
        /// <param name="model"></param>
        /// <returns></returns>
        public int Add(T model)
        {
            return idal.Add(model);
        }
        #endregion

        #region 2。0 根据 用户 id 删除 +int Del(int uId)
        /// <summary>
        /// 根据 用户 id 删除
        /// </summary>
        /// <param name="uId"></param>
        /// <returns></returns>
        public int Del(T model)
        {
            return idal.Del(model);
        }
        #endregion

        #region 3.0 根据条件删除 +int DelBy(Expression<Func<T, bool>> delWhere)
        /// <summary>
        /// 3.0 根据条件删除
        /// </summary>
        /// <param name="delWhere"></param>
        /// <returns></returns>
        public int DelBy(Expression<Func<T, bool>> delWhere)
        {
            return idal.DelBy(delWhere);
        }
        #endregion

        #region 4.0 修改 +int Modify(T model, params string[] proNames)
        /// <summary>
        /// 4.0 修改，如：
        /// </summary>
        /// <param name="model">要修改的实体对象</param>
        /// <param name="proNames">要修改的 属性 名称</param>
        /// <returns></returns>
        public int Modify(T model, params string[] proNames)
        {
            return idal.Modify(model, proNames);
        }
        #endregion

        #region  4.0 批量修改 +int Modify(T model, Expression<Func<T, bool>> whereLambda, params string[] modifiedProNames)
        /// <summary>
        ///  4.0 批量修改 +int Modify(T model, Expression<Func<T, bool>> whereLambda, params string[] modifiedProNames)
        /// </summary>
        /// <param name="model"></param>
        /// <param name="whereLambda"></param>
        /// <param name="modifiedProNames"></param>
        /// <returns></returns>
        public int ModifyBy(T model, Expression<Func<T, bool>> whereLambda, params string[] modifiedProNames)
        {
            return idal.ModifyBy(model, whereLambda, modifiedProNames);
        }
        #endregion

        #region 5.0 根据条件查询 +List<T> GetListBy(Expression<Func<T,bool>> whereLambda)
        /// <summary>
        /// 5.0 根据条件查询 +List<T> GetListBy(Expression<Func<T,bool>> whereLambda)
        /// </summary>
        /// <param name="whereLambda"></param>
        /// <returns></returns>
        public List<T> GetListBy(Expression<Func<T, bool>> whereLambda)
        {
            return idal.GetListBy(whereLambda);
        }
        #endregion

        #region 5.1 根据条件 排序 和查询 + List<T> GetListBy<TKey>
        /// <summary>
        /// 5.1 根据条件 排序 和查询
        /// </summary>
        /// <typeparam name="TKey">排序字段类型</typeparam>
        /// <param name="whereLambda">查询条件 lambda表达式</param>
        /// <param name="orderLambda">排序条件 lambda表达式</param>
        /// <returns></returns>
        public List<T> GetListBy<TKey>(Expression<Func<T, bool>> whereLambda, Expression<Func<T, TKey>> orderLambda)
        {
            return idal.GetListBy(whereLambda, orderLambda);
        }
        #endregion

        #region 6.0 分页查询 + List<T> GetPagedList<TKey>
        /// <summary>
        /// 6.0 分页查询 + List<T> GetPagedList<TKey>
        /// </summary>
        /// <param name="pageIndex">页码</param>
        /// <param name="pageSize">页容量</param>
        /// <param name="whereLambda">条件 lambda表达式</param>
        /// <param name="orderBy">排序 lambda表达式</param>
        /// <returns></returns>
        public List<T> GetPagedList<TKey>(int pageIndex, int pageSize, Expression<Func<T, bool>> whereLambda, Expression<Func<T, TKey>> orderBy)
        {
            return idal.GetPagedList(pageIndex, pageSize, whereLambda, orderBy);
        }
        #endregion
    }
}

8、同样的拷贝IBLL.tt到BLL项目下，重命名为BLL.tt，然后修改T4模板

public override void SetDAL()
  {
      idal = DBSession.I<#=entity.Name#>DAL;
  }

按Ctrl+S自动生成代码，自动生成的BLL.cs如下：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using IBLL;

namespace BLL
{
    public partial class Bill_LeaveBLL : BaseBLL<Model.Bill_Leave>,IBill_LeaveBLL
    {
        public override void SetDAL()
        {
         idal= DBSession.IBill_LeaveDAL;
        }
    }

    public partial class oldWF_AutoTransactNodeBLL : BaseBLL<Model.oldWF_AutoTransactNode>,IoldWF_AutoTransactNodeBLL
    {
        public override void SetDAL()
        {
         idal= DBSession.IoldWF_AutoTransactNodeDAL;
        }
    }

    public partial class oldWF_BillFlowNodeBLL : BaseBLL<Model.oldWF_BillFlowNode>,IoldWF_BillFlowNodeBLL
    {
        public override void SetDAL()
        {
         idal= DBSession.IoldWF_BillFlowNodeDAL;
        }
    }

    public partial class oldWF_BillFlowNodeRemarkBLL : BaseBLL<Model.oldWF_BillFlowNodeRemark>,IoldWF_BillFlowNodeRemarkBLL
    {
        public override void SetDAL()
        {
         idal= DBSession.IoldWF_BillFlowNodeRemarkDAL;
        }
    }

    public partial class oldWF_BillStateBLL : BaseBLL<Model.oldWF_BillState>,IoldWF_BillStateBLL
    {
        public override void SetDAL()
        {
         idal= DBSession.IoldWF_BillStateDAL;
        }
    }

    public partial class oldWF_NodeBLL : BaseBLL<Model.oldWF_Node>,IoldWF_NodeBLL
    {
        public override void SetDAL()
        {
         idal= DBSession.IoldWF_NodeDAL;
        }
    }

    public partial class oldWF_NodeStateBLL : BaseBLL<Model.oldWF_NodeState>,IoldWF_NodeStateBLL
    {
        public override void SetDAL()
        {
         idal= DBSession.IoldWF_NodeStateDAL;
        }
    }

    public partial class oldWF_WorkFlowBLL : BaseBLL<Model.oldWF_WorkFlow>,IoldWF_WorkFlowBLL
    {
        public override void SetDAL()
        {
         idal= DBSession.IoldWF_WorkFlowDAL;
        }
    }

    public partial class oldWF_WorkFlowNodeBLL : BaseBLL<Model.oldWF_WorkFlowNode>,IoldWF_WorkFlowNodeBLL
    {
        public override void SetDAL()
        {
         idal= DBSession.IoldWF_WorkFlowNodeDAL;
        }
    }

    public partial class Ou_DepartmentBLL : BaseBLL<Model.Ou_Department>,IOu_DepartmentBLL
    {
        public override void SetDAL()
        {
         idal= DBSession.IOu_DepartmentDAL;
        }
    }

    public partial class Ou_PermissionBLL : BaseBLL<Model.Ou_Permission>,IOu_PermissionBLL
    {
        public override void SetDAL()
        {
         idal= DBSession.IOu_PermissionDAL;
        }
    }

    public partial class Ou_RoleBLL : BaseBLL<Model.Ou_Role>,IOu_RoleBLL
    {
        public override void SetDAL()
        {
         idal= DBSession.IOu_RoleDAL;
        }
    }

    public partial class Ou_RolePermissionBLL : BaseBLL<Model.Ou_RolePermission>,IOu_RolePermissionBLL
    {
        public override void SetDAL()
        {
         idal= DBSession.IOu_RolePermissionDAL;
        }
    }

    public partial class Ou_UserInfoBLL : BaseBLL<Model.Ou_UserInfo>,IOu_UserInfoBLL
    {
        public override void SetDAL()
        {
         idal= DBSession.IOu_UserInfoDAL;
        }
    }

    public partial class Ou_UserRoleBLL : BaseBLL<Model.Ou_UserRole>,IOu_UserRoleBLL
    {
        public override void SetDAL()
        {
         idal= DBSession.IOu_UserRoleDAL;
        }
    }

    public partial class Ou_UserVipPermissionBLL : BaseBLL<Model.Ou_UserVipPermission>,IOu_UserVipPermissionBLL
    {
        public override void SetDAL()
        {
         idal= DBSession.IOu_UserVipPermissionDAL;
        }
    }

    public partial class W_WorkFlowBLL : BaseBLL<Model.W_WorkFlow>,IW_WorkFlowBLL
    {
        public override void SetDAL()
        {
         idal= DBSession.IW_WorkFlowDAL;
        }
    }

    public partial class W_WorkFlowBranchBLL : BaseBLL<Model.W_WorkFlowBranch>,IW_WorkFlowBranchBLL
    {
        public override void SetDAL()
        {
         idal= DBSession.IW_WorkFlowBranchDAL;
        }
    }

    public partial class W_WorkFlowNodeBLL : BaseBLL<Model.W_WorkFlowNode>,IW_WorkFlowNodeBLL
    {
        public override void SetDAL()
        {
         idal= DBSession.IW_WorkFlowNodeDAL;
        }
    }

    public partial class W_WrokFlowRoleBLL : BaseBLL<Model.W_WrokFlowRole>,IW_WrokFlowRoleBLL
    {
        public override void SetDAL()
        {
         idal= DBSession.IW_WrokFlowRoleDAL;
        }
    }

    public partial class WR_WorkFlowApplyBLL : BaseBLL<Model.WR_WorkFlowApply>,IWR_WorkFlowApplyBLL
    {
        public override void SetDAL()
        {
         idal= DBSession.IWR_WorkFlowApplyDAL;
        }
    }

    public partial class WR_WrokFlowApplyDetailsBLL : BaseBLL<Model.WR_WrokFlowApplyDetails>,IWR_WrokFlowApplyDetailsBLL
    {
        public override void SetDAL()
        {
         idal= DBSession.IWR_WrokFlowApplyDetailsDAL;
        }
    }

}

到此，业务父类、业务类、数据父类、数据类都已经创建好了，里面有些东西还需要优化的，后续一步一步完善。