使用NHibernate3.0来构建自己的ORM框架(一)

1. Library文件

  需要的dll文件如下：

  FluentNHibernate.dll (*)

  NHibernate.ByteCode.Castle.dll (*)

  NHibernate.dll (*)

  Remotion.Data.Linq.dll

  Antlr3.Runtime.dll

  Castle.Core.dll

  Iesi.Collections.dll

2. 创建Hibernate访问通用类

using System;
using System.Collections.Generic;
using FluentNHibernate.Cfg;
using FluentNHibernate.Cfg.Db;
using NHibernate;
using NHibernate.Cfg;
using NHibernate.Tool.hbm2ddl;
using NHibernate.Linq;
using System.Linq;

namespace CsharpTrainer.NHibernate3
{
    public class NHibernateDb<TMap> : IDisposable
    {
        private string connString;
        private ISessionFactory sessFactory;
        private ISession session;

        public ISessionFactory SessionFactory
        {
            get { return sessFactory; }
            set { sessFactory = value; }
        }

        public ISession Session
        {
            get { return session; }
            set { session = value; }
        }

        public void Dispose()
        {
            session.Dispose();
        }

        public NHibernateDb(string pStr)
        {
            connString = pStr;
            sessFactory = CreateSessionFactory();
            session = sessFactory.OpenSession();
        }

        ~NHibernateDb()
        {
            try
            {
                Dispose();
            }
            catch 
            {
                Console.WriteLine("Exception: session dispose failed!");
            }
        }

        private ISessionFactory CreateSessionFactory()
        {
            return Fluently.Configure()
                .Database(MsSqlConfiguration
                              .MsSql2008
                              .ConnectionString(connString))
                .Mappings(m => m.FluentMappings
                                   .AddFromAssemblyOf<TMap>())
                .BuildSessionFactory();
        }
        
        private void CreateSchema(Configuration cfg)
        {
            var schemaExport = new SchemaExport(cfg);
            schemaExport.Drop(false, true);
            schemaExport.Create(false, true);
        }

        public void CreateDatabase()
        {
            Fluently.Configure()
                .Database(MsSqlConfiguration.MsSql2008.ConnectionString(connString))
                .Mappings(m => m.FluentMappings.AddFromAssemblyOf<TMap>())
                .ExposeConfiguration(CreateSchema)
                .BuildConfiguration();
        }
    }
}

3. 创建表格对应的实体类

  我们以Northwind数据库的Employees表格为例

using System;

namespace CsharpTrainer.NHibernate3.Entities
{
    public class Employees
    {
        public virtual int EmployeeID { get; set; }
        public virtual string LastName { get; set; }
        public virtual string FirstName { get; set; }
        public virtual string Title { get; set; }
        public virtual DateTime BirthDate { get; set; }
        public virtual string Address { get; set; }
        public virtual string City { get; set; }
        public virtual string Region { get; set; }
        public virtual string Country { get; set; }
        public virtual string Notes { get; set; }

        public override string ToString()
        {
            string format = "Employee ID: {0}\nLast Name: {1}\n"
                          + "First Name: {2}\nTitle: {3}\nBirth Date: {4}\n"
                          + "Address: {5}\nCity: {6}\nRegion: {7}\nCountry: {8}\n"
                          + "Notes: {9}\n";

            return string.Format(format, EmployeeID, LastName, FirstName,
                                    Title, BirthDate, Address, City, Region, Country, Notes);
        }
    }
}

4. 建立映射关系(映射类)

  EmployeeMap Class:

using FluentNHibernate.Mapping;
using CsharpTrainer.NHibernate3.Entities;

namespace CsharpTrainer.NHibernate3.Mapping
{
    public class EmployeeMap : ClassMap<Employees>
    {
        public EmployeeMap()
        {
            Id(x => x.EmployeeID, "EmployeeID");
            Map(x => x.LastName)
                .Length(20)
                .Not.Nullable();
            Map(x => x.FirstName)
                .Length(10)
                .Not.Nullable();
            Map(x => x.Title)
                .Length(30);
            Map(x => x.BirthDate);
            Map(x => x.Address)
                .Length(60);
            Map(x => x.City)
                .Length(15);
            Map(x => x.Region)
                .Length(15);
            Map(x => x.Country)
                .Length(15);
            Map(x => x.Notes);
        }
    }
}

5. 客户端查询代码

  查询所有的员工，按照LastName排序

public void Run()
        {
            string connStr = ConfigurationManager.ConnectionStrings["NorthwindConnStr"].ConnectionString;

            try
            {
                NHibernateDb<EmployeeMap> db = new NHibernateDb<EmployeeMap>(connStr);

                ISessionFactory factory = db.SessionFactory;
                using (var session = factory.OpenSession())
                {
                    var employees = session.QueryOver<Employees>()
                                    .OrderBy(a => a.LastName).Asc
                                    .List();
                    Console.WriteLine("All Employees Below:");
                    foreach (var employee in employees)
                    {
                        Console.WriteLine(employee);
                    }
                }
                
            }
            catch (Exception ex)
            {
                Console.WriteLine("Exception: " + ex.ToString());
            }
        }