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!
层级结构
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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各层级搭建
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
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| using System.Data.Entity; using System.Runtime.Remoting.Messaging; using PMS.Model;
namespace PMS.DAL { public class DbContextFactory { public static DbContext CreateContext() { DbContext dbContext = (DbContext)CallContext.GetData("dbContext"); if (dbContext != null) return dbContext; dbContext = new PMSEntities(); CallContext.SetData("dbContext", dbContext); return dbContext; } } }
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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
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| using System; using System.Data.Entity; using System.Linq; using PMS.IDAL;
namespace PMS.DAL { public partial class UserDal
{ public DbContext DbEntities = DbContextFactory.CreateContext();
public IQueryable<UserDal> LoadEntities(System.Linq.Expressions.Expression<Func<UserDal, bool>> whereLamada) { return DbEntities.Set<UserDal>().Where(whereLamada); }
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; }
public bool DeleteEntity(UserDal entity) { DbEntities.Entry(entity).State = EntityState.Deleted; return true; }
public bool EditEntity(UserDal entity) { DbEntities.Entry(entity).State = EntityState.Modified; return true; }
public UserDal AddEntity(UserDal entity) { entity = DbEntities.Set<UserDal>().Add(entity); return entity; } } }
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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
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| 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();
public IQueryable<T> LoadEntities(System.Linq.Expressions.Expression<Func<T, bool>> whereLamada) { return DbEntities.Set<T>().Where(whereLamada); }
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; }
public bool DeleteEntity(T entity) { DbEntities.Entry(entity).State = EntityState.Deleted; return true; }
public bool EditEntity(T entity) { DbEntities.Entry(entity).State = EntityState.Modified; return true; }
public T AddEntity(T entity) { entity = DbEntities.Set<T>().Add(entity); return entity; } } }
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UserDal继承BaseDal
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| using PMS.IDAL; using PMS.Model;
namespace PMS.DAL { public partial class UserDal : BaseDal<User> { } }
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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:
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| 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); } }
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IUserDal:
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| using PMS.Model;
namespace PMS.IDAL { public partial interface IUserDal:IBaseDal<User> {
} }
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UserDal实现IUserDal接口:
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| public partial class UserDal : BaseDal<User>,IUserDal
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数据会话层的构建
抽象工厂类AbstractFactory:
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| using System.Configuration; using System.Reflection; using PMS.IDAL;
namespace PMS.DALFactory { public partial class AbstractFactory { private static readonly string AssemblyPath = ConfigurationManager.AppSettings["AssemblyPath"]; private static readonly string NameSpace = ConfigurationManager.AppSettings["NameSpace"]; public static IUserDal CreateUserInfoDal() { var fullClassName = NameSpace + ".UserInfoDal"; return CreateInstance(fullClassName) as IUserDal; } private static object CreateInstance(string className) { var assembly = Assembly.Load(AssemblyPath); return assembly.CreateInstance(className); } } }
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数据会话类DbSession:
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| 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; } }
public bool SaveChanges() { return Db.SaveChanges() > 0; } } }
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业务逻辑层的构建
业务类基类BaseService
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| 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(); }
public IQueryable<T> LoadEntities(Expression<Func<T, bool>> whereLambda) { return CurrentDal.LoadEntities(whereLambda); }
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); }
public bool DeleteEntity(T entity) { CurrentDal.DeleteEntity(entity); return CurrentDbSession.SaveChanges(); }
public bool EditEntity(T entity) { CurrentDal.EditEntity(entity); return CurrentDbSession.SaveChanges(); }
public T AddEntity(T entity) { CurrentDal.AddEntity(entity); CurrentDbSession.SaveChanges(); return entity; } } }
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UserService类:
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| using PMS.IBLL; using PMS.Model;
namespace PMS.BLL { public partial class UserService : BaseService<User> { public override void SetCurrentDal() { CurrentDal = CurrentDbSession.UserDal; } } }
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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:
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| 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); } }
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IUserService接口:
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| using PMS.Model;
namespace PMS.IBLL { public partial interface IUserService:IBaseService<User> {
} }
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使用UserService类实现IUserService接口:
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| public partial class UserService : BaseService<User>, IUserService
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以上我们就完成了整个框架中关于User类的各层次的实现。