新人刚开始学习ASP.NET MVC，若有不足之处希望能得到您的指点，不胜感激！
先来一张项目的层级结构图:
Model：模型层，主要是各种类型、枚举以及ORM框架，框架完成数据库和实体类的映射。项目中选用了微软的开源ORM框架 EntityFramework 6.0 （以下简称EF），数据库则选择了微软的轻量级数据库SQL Server Compact 4.0本地数据库（简称Compact），Compact对EF支持比较完美，又属于文档型数据库，部署起来比较简洁。
DAL：数据访问层，主要是对数据库的操作层，为业务逻辑层或表示层提供数据服务。
IDAL：数据访问接口层，是数据访问层的接口，降低耦合。
DALFactory：数据会话层，封装了所有数据操作类实例的创建，将数据访问层与业务逻辑层解耦。
BLL：业务逻辑层，主要负责对数据层的操作，把一些数据层的操作进行组合以完成业务的需要。
IBLL：业务逻辑接口层，业务逻辑层的接口，降低耦合。
WebApp：表现层，是一个ASP.NET MVC项目，完成具体网站的实现。
Common：通用层，用来存放一些工具类。
下面是各个层级之间具体的实现，首先创建以 项目名.层级名 命名的各个层次，除WebApp层为ASP.NET MVC项目外，其余均创建为类库项目。
模型层的构建
先建立模型层，新建ASP.NET 实体数据模型，关联到已经设计好的数据库，EF自动完成模型类的创建。
数据访问层的构建
DAL层中，我们首先需要一个方法来获取单例的EF数据操纵上下文对象，以保证每个用户访问时只有使用一个上下文对象对数据库进行操作。
DbContextFactory.cs
using System.Data.Entity;
using System.Runtime.Remoting.Messaging;
using PMS.Model;
namespace PMS.DAL
{
public class DbContextFactory
{
/// <summary>
/// 负责创建EF数据操作上下文实例,必须保证线程内唯一
/// </summary>
public static DbContext CreateContext()
{
DbContext dbContext = (DbContext)CallContext.GetData("dbContext");
if (dbContext != null) return dbContext;
dbContext = new PMSEntities();
CallContext.SetData("dbContext", dbContext);
return dbContext;
}
}
}
为User类创建DAL层，实现查询、分页查询、增加、删除和修改这五个基本的方法：
UserDAL.cs
using System;
using System.Data.Entity;
using System.Linq;
using PMS.IDAL;
namespace PMS.DAL
{
public partial class UserDal {
public DbContext DbEntities = DbContextFactory.CreateContext();
/// <summary>
/// 查询过滤
/// </summary>
/// <param name="whereLamada">过滤条件Lambda表达式</param>
/// <returns>实体集合</returns>
public IQueryable<UserDal> LoadEntities(System.Linq.Expressions.Expression<Func<UserDal, bool>> whereLamada)
{
return DbEntities.Set<UserDal>().Where(whereLamada);
}
/// <summary>
/// 分页查询
/// </summary>
/// <typeparam name="TS">排序类型</typeparam>
/// <param name="pageIndex">查询的页码</param>
/// <param name="pageSize">每页显示的数目</param>
/// <param name="totalCount">符合条件的总行数</param>
/// <param name="whereLambda">过滤条件Lambda表达式</param>
/// <param name="orderbyLambda">排序Lambda表达式</param>
/// <param name="isAsc">排序方向</param>
/// <returns>实体集合</returns>
public IQueryable<UserDal> LoadPageEntities<TS>(int pageIndex, int pageSize, out int totalCount, System.Linq.Expressions.Expression<Func<UserDal, bool>> whereLambda, System.Linq.Expressions.Expression<Func<UserDal, TS>> orderbyLambda, bool isAsc)
{
var temp = DbEntities.Set<UserDal>().Where(whereLambda);
totalCount = temp.Count();
temp = isAsc ? temp.OrderBy(orderbyLambda).Skip((pageIndex - 1) * pageSize).Take(pageSize) : temp.OrderByDescending(orderbyLambda).Skip((pageIndex - 1) * pageSize).Take(pageSize);
return temp;
}
/// <summary>
/// 删除数据
/// </summary>
/// <param name="entity">待删数据</param>
/// <returns>删除结果</returns>
public bool DeleteEntity(UserDal entity)
{
DbEntities.Entry(entity).State = EntityState.Deleted;
return true;
}
/// <summary>
/// 编辑数据
/// </summary>
/// <param name="entity">待编辑数据</param>
/// <returns>编辑结果</returns>
public bool EditEntity(UserDal entity)
{
DbEntities.Entry(entity).State = EntityState.Modified;
return true;
}
/// <summary>
/// 添加数据
/// </summary>
/// <param name="entity">待添加数据</param>
/// <returns>已添加数据</returns>
public UserDal AddEntity(UserDal entity)
{
entity = DbEntities.Set<UserDal>().Add(entity);
return entity;
}
}
}
注：这里的增删改操作并不即时进行，而是在封装在数据会话层中，以实现工作单元模式，提高数据库的操作效率。
考虑到每个类都需要实现相同的数据操作，我们可以将以上方法封装到一个泛型基类中，各类型只需要继承泛型基类就可以实现以上方法：
BaseDal.cs
using System;
using System.Data.Entity;
using System.Linq;
namespace PMS.DAL
{
public class BaseDal<T> where T:class ,new()
{
public DbContext DbEntities = DbContextFactory.CreateContext();
/// <summary>
/// 查询过滤
/// </summary>
/// <param name="whereLamada">过滤条件Lambda表达式</param>
/// <returns>实体集合</returns>
public IQueryable<T> LoadEntities(System.Linq.Expressions.Expression<Func<T, bool>> whereLamada)
{
return DbEntities.Set<T>().Where(whereLamada);
}
/// <summary>
/// 分页查询
/// </summary>
/// <typeparam name="TS">排序类型</typeparam>
/// <param name="pageIndex">查询的页码</param>
/// <param name="pageSize">每页显示的数目</param>
/// <param name="totalCount">符合条件的总行数</param>
/// <param name="whereLambda">过滤条件Lambda表达式</param>
/// <param name="orderbyLambda">排序Lambda表达式</param>
/// <param name="isAsc">排序方向</param>
/// <returns>实体集合</returns>
public IQueryable<T> LoadPageEntities<TS>(int pageIndex, int pageSize, out int totalCount, System.Linq.Expressions.Expression<Func<T, bool>> whereLambda, System.Linq.Expressions.Expression<Func<T, TS>> orderbyLambda, bool isAsc)
{
var temp = DbEntities.Set<T>().Where(whereLambda);
totalCount = temp.Count();
temp = isAsc ? temp.OrderBy(orderbyLambda).Skip((pageIndex - 1) * pageSize).Take(pageSize) : temp.OrderByDescending(orderbyLambda).Skip((pageIndex - 1) * pageSize).Take(pageSize);
return temp;
}
/// <summary>
/// 删除数据
/// </summary>
/// <param name="entity">待删数据</param>
/// <returns>删除结果</returns>
public bool DeleteEntity(T entity)
{
DbEntities.Entry(entity).State = EntityState.Deleted;
return true;
}
/// <summary>
/// 编辑数据
/// </summary>
/// <param name="entity">待编辑数据</param>
/// <returns>编辑结果</returns>
public bool EditEntity(T entity)
{
DbEntities.Entry(entity).State = EntityState.Modified;
return true;
}
/// <summary>
/// 添加数据
/// </summary>
/// <param name="entity">待添加数据</param>
/// <returns>已添加数据</returns>
public T AddEntity(T entity)
{
entity = DbEntities.Set<T>().Add(entity);
//DbEntities.SaveChanges();
return entity;
}
}
}
UserDal继承BaseDal
using PMS.IDAL;
using PMS.Model;
namespace PMS.DAL
{
public partial class UserDal : BaseDal<User>
{
}
}
数据访问接口层的构建
然后我们建立相应的IbaseDal接口和IUserDal接口，并且使UserDal类实现IUserDal接口
IBaseDal：
using System;
using System.Linq;
namespace PMS.IDAL
{
public interface IBaseDal<T> where T:class,new()
{
IQueryable<T> LoadEntities(System.Linq.Expressions.Expression<Func<T, bool>> whereLamada);
IQueryable<T> LoadPageEntities<s>(int pageIndex, int pageSize, out int totalCount,
System.Linq.Expressions.Expression<Func<T, bool>> whereLambda,
System.Linq.Expressions.Expression<Func<T, s>> orderbyLambda, bool isAsc);
bool DeleteEntity(T entity);
bool EditEntity(T entity);
T AddEntity(T entity);
}
}
IUserDal：
using PMS.Model;
namespace PMS.IDAL
{
public partial interface IUserDal:IBaseDal<User>
{
}
}
UserDal实现IUserDal接口：
public partial class UserDal : BaseDal<User>,IUserDal
数据会话层的构建
抽象工厂类AbstractFactory：
using System.Configuration;
using System.Reflection;
using PMS.IDAL;
namespace PMS.DALFactory
{
public partial class AbstractFactory
{
//读取保存在配置文件中的程序集名称与命名空间名
private static readonly string AssemblyPath = ConfigurationManager.AppSettings["AssemblyPath"];
private static readonly string NameSpace = ConfigurationManager.AppSettings["NameSpace"];
/// <summary>
/// 获取UserDal的实例
/// </summary>
/// <returns></returns>
public static IUserDal CreateUserInfoDal()
{
var fullClassName = NameSpace + ".UserInfoDal";
return CreateInstance(fullClassName) as IUserDal;
}
/// <summary>
/// 通过反射获得程序集中某类型的实例
/// </summary>
/// <param name="className"></param>
/// <returns></returns>
private static object CreateInstance(string className)
{
var assembly = Assembly.Load(AssemblyPath);
return assembly.CreateInstance(className);
}
}
}
数据会话类DbSession：
using System.Data.Entity;
using PMS.IDAL;
using PMS.DAL;
namespace PMS.DALFactory
{
public partial class DbSession:IDbSession
{
public DbContext Db
{
get { return DbContextFactory.CreateContext(); }
}
private IUserDal _userDal;
public IUserDal UserDal
{
get { return _userDal ?? (_userDal = AbstractFactory.CreateUserInfoDal()); }
set { _userDal = value; }
}
/// <summary>
/// 工作单元模式，统一保存数据
/// </summary>
/// <returns></returns>
public bool SaveChanges()
{
return Db.SaveChanges() > 0;
}
}
}
业务逻辑层的构建
业务类基类BaseService
using System;
using System.Linq;
using System.Linq.Expressions;
using PMS.DALFactory;
using PMS.IDAL;
namespace PMS.BLL
{
public abstract class BaseService<T> where T:class,new()
{
public IDbSession CurrentDbSession
{
get
{
return new DbSession();
}
}
public IBaseDal<T> CurrentDal { get; set; }
public abstract void SetCurrentDal();
public BaseService()
{
SetCurrentDal();//子类一定要实现抽象方法，以指明当前类的子类类型。
}
/// <summary>
/// 查询过滤
/// </summary>
/// <param name="whereLambda"></param>
/// <returns></returns>
public IQueryable<T> LoadEntities(Expression<Func<T, bool>> whereLambda)
{
return CurrentDal.LoadEntities(whereLambda);
}
/// <summary>
/// 分页
/// </summary>
/// <typeparam name="s"></typeparam>
/// <param name="pageIndex"></param>
/// <param name="pageSize"></param>
/// <param name="totalCount"></param>
/// <param name="whereLambda"></param>
/// <param name="orderbyLambda"></param>
/// <param name="isAsc"></param>
/// <returns></returns>
public IQueryable<T> LoadPageEntities<s>(int pageIndex, int pageSize, out int totalCount, Expression<Func<T, bool>> whereLambda,
Expression<Func<T, s>> orderbyLambda, bool isAsc)
{
return CurrentDal.LoadPageEntities<s>(pageIndex, pageSize, out totalCount, whereLambda, orderbyLambda, isAsc);
}
/// <summary>
/// 删除
/// </summary>
/// <param name="entity"></param>
/// <returns></returns>
public bool DeleteEntity(T entity)
{
CurrentDal.DeleteEntity(entity);
return CurrentDbSession.SaveChanges();
}
/// <summary>
/// 编辑
/// </summary>
/// <param name="entity"></param>
/// <returns></returns>
public bool EditEntity(T entity)
{
CurrentDal.EditEntity(entity);
return CurrentDbSession.SaveChanges();
}
/// <summary>
/// 添加数据
/// </summary>
/// <param name="entity"></param>
/// <returns></returns>
public T AddEntity(T entity)
{
CurrentDal.AddEntity(entity);
CurrentDbSession.SaveChanges();
return entity;
}
}
}
UserService类：
using PMS.IBLL;
using PMS.Model;
namespace PMS.BLL
{
public partial class UserService : BaseService<User>
{
public override void SetCurrentDal()
{
CurrentDal = CurrentDbSession.UserDal;
}
}
}
业务逻辑接口层的构建
直接建立对应的接口并使用UserService类实现IUserService接口
IBaseService接口：
using System;
using System.Linq;
using System.Linq.Expressions;
using PMS.IDAL;
namespace PMS.IBLL
{
public interface IBaseService<T> where T : class,new()
{
IDbSession CurrentDbSession { get; }
IBaseDal<T> CurrentDal { get; set; }
void SetCurrentDal();
IQueryable<T> LoadEntities(Expression<Func<T, bool>> whereLambda);
IQueryable<T> LoadPageEntities<s>(int pageIndex, int pageSize, out int totalCount,
Expression<Func<T, bool>> whereLambda,
Expression<Func<T, s>> orderbyLambda, bool isAsc);
bool DeleteEntity(T entity);
bool EditEntity(T entity);
T AddEntity(T entity);
}
}
IUserService接口:
using PMS.Model;
namespace PMS.IBLL
{
public partial interface IUserService:IBaseService<User>
{
}
}
使用UserService类实现IUserService接口:
public partial class UserService : BaseService<User>, IUserService
以上我们就完成了整个框架中关于User类的各层次的实现。
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