NHibernate系列文章十六：使用程序集管理NHibernate项目（附程序下载）

摘要

在实际的项目中，经常是将NHibernate的实体关系映射类做成独立的工程（assembly dll），只对外提供Session调用的接口。这个程序集作为数据访问层，可以被上面的多个工程（ASP.Net、Windows Form、Windows Serviice等）调用。

这篇文章介绍如何设计NHibernate数据访问层的工程，以及如何架构数据访问层和上面的应用层的关系。

本文章的所有代码可以到第一个NHibernate程序下载。

步骤：

1）为了后面文章的程序演示方便，删除Customer表，新建主键类型是int类型，主键生成方法是IDENTITY的Customer表。

CREATE TABLE [dbo].[Customer](
    [Id] [int] IDENTITY(1,1) NOT NULL,
    [FirstName] [nvarchar](10) NOT NULL,
    [LastName] [nvarchar](10) NOT NULL,
    [Points] [int] NULL,
    [HasGoldStatus] [bit] NULL,
    [MemberSince] [date] NULL,
    [CreditRating] [nchar](20) NULL,
    [AverageRating] [decimal](18, 4) NULL,
    [Street] [nvarchar](100) NULL,
    [City] [nvarchar](100) NULL,
    [Province] [nvarchar](100) NULL,
    [Country] [nvarchar](100) NULL,
 CONSTRAINT [PK_Customer] PRIMARY KEY CLUSTERED 
(
    [Id] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]

2）添加Class Library：NHibernateDemoAPP.XML.Entities。删除Class1.cs文件。

这里使用XML映射，因此这里用NHibernateDemoAPP.XML.Entities作为工程名。实际项目的工程名称应该没有"XML"。

3）在NHibernateDemoAPP.XML.Entities工程里添加文件夹Domain和hbm。也可以创建名称为Mapping的文件夹，替代这里的hbm文件夹，看个人喜好。

4）将NHibernateDemoApp工程的文件Address.cs、Customer.cs移动到Domain文件夹。将文件Customer.hbm.xml移动到hbm文件夹。在NHibernateDemoApp工程里删除文件Address.cs、Customer.cs和Customer.hbm.xml。

5）修改NHibernateDemoApp工程的文件hibernate.hbm.xml。修改mapping节点的assembly属性。

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-configuration xmlns="urn:nhibernate-configuration-2.2">
<session-factory>
<property name="connection.connection_string_name">default</property>
<property name="connection.driver_class">NHibernate.Driver.SqlClientDriver</property>
<property name="dialect">NHibernate.Dialect.MsSql2008Dialect</property>
<mapping assembly="NHibernateDemoAPP.XML.Entities"/>
</session-factory>
</hibernate-configuration>

6）修改Customer.cs的namespace。将Id属性改成int。

using System;

namespace NHibernateDemoAPP.XML.Entities.Domain
{
    public class Customer
    {
        public virtual int Id { get; set; }
        public virtual string FirstName { get; set; }
        public virtual string LastName { get; set; }
        public virtual double AverageRating { get; set; }
        public virtual int Points { get; set; }
        public virtual bool HasGoldStatus { get; set; }
        public virtual DateTime MemberSince { get; set; }
        public virtual CustomerCreditRating CreditRating { get; set; }
        public virtual Address Address { get; set; }
    }

    public enum CustomerCreditRating
    {
        Excellent, VeryVeryGood, VeryGood, Good, Neutral, Poor, Terrible
    }
}

7）修改Customer.hbm.xml文件。修改根节点hibernate-mapping的assembly属性和namespace属性。

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="NHibernateDemoAPP.XML.Entities" namespace="NHibernateDemoAPP.XML.Entities.Domain">
  <class name="Customer" table="Customer">
    <id name="Id">
      <generator class="native"/>
    </id>
    <property name="FirstName" not-null="true"/>
    <property name="LastName" not-null ="true"/>
    <property name="AverageRating"/>
    <property name="Points"/>
    <property name="HasGoldStatus"/>
    <property name="MemberSince"/>
    <property name="CreditRating" type="CustomerCreditRating"/>
    <component name="Address">
      <property name="Street"/>
      <property name="City"/>
      <property name="Province"/>
      <property name="Country"/>
    </component>
  </class>
</hibernate-mapping>

8）为工程NHibernateDemoApp添加工程NHibernateDemoAPP.XML.Entities的引用。

9）修改Program.cs文件。

using NHibernate;
using NHibernate.Cfg;
using NHibernateDemoAPP.XML.Entities.Domain;
using System;
using System.Collections.Generic;

namespace NHibernateDemoApp
{
    class Program
    {
        private static ISessionFactory _sessionFactory;

        private static ISession _session;

        public static ISessionFactory SessionFactory
        {
            get
            {
                if (_sessionFactory == null)
                {
                    var cfg = new Configuration();
                    cfg.Configure();
                    _sessionFactory = cfg.BuildSessionFactory();
                }
                return _sessionFactory;
            }
        }

        public static ISession Session
        {
            get
            {
                if (_session == null)
                {
                    _session = SessionFactory.OpenSession();
                }
                return _session;
            }
        }


        static void Main(string[] args)
        {
            HibernatingRhinos.Profiler.Appender.NHibernate.NHibernateProfiler.Initialize();

            using (var session = SessionFactory.OpenSession())
            {
                var customer = CreateCustomer();
                object custoemrId = session.Save(customer);
                session.Flush();

                customer = session.Get<Customer>(custoemrId);
                Console.WriteLine(customer.LastName);
            }

            Console.WriteLine("Completed");
            Console.ReadLine();
        }

        private static Customer CreateCustomer()
        {
            var customer = new Customer
            {
                FirstName = "Daniel",
                LastName = "Tang",
                Points = 100,
                HasGoldStatus = true,
                MemberSince = new DateTime(2012, 1, 1),
                CreditRating = CustomerCreditRating.Good,
                AverageRating = 42.42424242,
                Address = new Address
                {
                    Street = "123 Somewhere Avenue",
                    City = "Nowhere",
                    Province = "Alberta",
                    Country = "Canada"
                }
            };
            
            return customer;
        }

        private static void UpdateInTransaction(Customer customer)
        {
            using (var transaction = Session.BeginTransaction())
            {
                try
                {
                    Session.Update(customer);
                    transaction.Commit();
                }
                catch (HibernateException e)
                {
                    transaction.Rollback();
                    throw e;
                }
            }
        }

        private static IList<Customer> GetAll()
        {
            using (var session = SessionFactory.OpenSession())
            {
                IList<Customer> list = session.CreateCriteria<Customer>().List<Customer>();
                return list;
            }
        }

        private static Customer GetById(Guid id)
        {
            using (var session = SessionFactory.OpenSession())
            {
                Customer customer = session.Get<Customer>(id);
                return customer;
            }
        }

        private static Customer LoadById(Guid id)
        {
            using (var session = SessionFactory.OpenSession())
            {
                Customer customer = session.Load<Customer>(id);
                return customer;
            }
        }

        private static int Insert(Customer customer)
        {
            using (var session = SessionFactory.OpenSession())
            {
                var identifier = session.Save(customer);
                session.Flush();
                return Convert.ToInt32(identifier);
            }
        }

        private static void Update(Customer customer)
        {
            using (var session = SessionFactory.OpenSession())
            {
                session.SaveOrUpdate(customer);
                session.Flush();
            }
        }

        private static void Delete(int id)
        {
            using (var session = SessionFactory.OpenSession())
            {
                var customer = session.Get<Customer>(id);
                session.Delete(customer);
                session.Flush();
            }
        }
    }
}

9）执行程序，将一条Customer对象插入到数据库记录中。

下一篇文章介绍如何在应用层（ASP.Net MVC, ASP.Net Web, Windows Form, Windows Service）中管理SessionFactory对象和Session对象。