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[ASP.net教程][MVC学习笔记]1.项目结构搭建及单个类在各个层次中的实现


      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:

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      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。

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      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。

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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。