设计模式学习日记二(持续更新)

上一篇主要介绍了一些设计原则和模式，本章来详细介绍一下Active Record模式，一个Blog小程序。

导航到http://sourceforge.net/projects/castleproject/files/ActiveRecord/3.0/Castle.ActiveRecord-3.0.RC.zip/download下载ActiveRecord项目的最新版。

创建名为 Terminator.Practice.ActiveRecord 的解决方案，添加名为 Terminator.Practice.ActiveRecord.Model 的C#类库和一个名为 Terminator.Practice.ActiveRecord.UI.MVC 的MVC应用程序（demo中使用的是MVC2.0）。

在解决方案创建一个名为Lib的文件夹，将Castle ActiveRecord下载文件放入其中，为Model项目添加Lib文件夹下的所有引用，MVC项目需要添加Castle.ActiveRecord.dll、NHibernate.dll以及对Model项目的引用。

创建Blog.mdf数据库，两张表Posts(Id,Subject,Text,DateAdd)和Comments(Id,Text,Author,DateAdd,PostId)

向Model项目添加一个Comment类：

using System;
using Castle.ActiveRecord;

namespace Terminator.Practice.ActiveRecord.Model
{
    [ActiveRecord("Comments")]
    public class Comment : ActiveRecordBase<Comment> 
    {       
        [PrimaryKey]
        public int Id { get; set; }

        [BelongsTo("PostID")]
        public Post Post { get; set; }

        [Property]
        public string Text { get; set; }

        [Property]
        public string Author { get; set; }

        [Property]
        public DateTime DateAdded { get; set; }
    }
}

用来修饰Comment类属性的特性会提示框架这些属性与数据库表的列相匹配。然后，Castle ActiveRecord框架使用该信息来自动完成业务实体持久化和检索，而不必要编写冗长的sql语句。

添加Post类：

using System;
using System.Collections.Generic;
using Castle.ActiveRecord;
using Castle.ActiveRecord.Queries;

namespace Terminator.Practice.ActiveRecord.Model
{
    [ActiveRecord("Posts")]
    public class Post : ActiveRecordBase<Post>
    {
        [PrimaryKey]
        public int Id { get; set; }

        [Property]
        public string Subject { get; set; }

        [Property]
        public string Text { get; set; }

        public string ShortText
        {
            get
            {
                if (Text.Length > 20)
                    return Text.Substring(0, 20) + "...";
                return Text;
            }
        }

        [HasMany]
        public IList<Comment> Comments { get; set; }

        [Property]
        public DateTime DateAdded { get; set; }

        public static Post FindLastestPost()
        {
            SimpleQuery<Post> q = new SimpleQuery<Post>(@"from Post p order by p.DateAdded desc");
            return q.Execute()[0];
        }
    }
}

这就是模型和数据访问的全部代码。非常的简单，这也正是Ruby on Rails开发者们一直炫耀的技术。

现在可以构造网站来显示帖子和评论。

添加一个名为BlogController的控制器：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web.Mvc;
using Terminator.Practice.ActiveRecord.Model;

namespace Terminator.Practice.ActiveRecord.UI.MVC.Controllers
{
    public class BlogController : Controller
    {
        // GET: /Blog/
        public ActionResult Index()
        {
            Post[] posts = Post.FindAll();

            if (posts.Any())
            {
                ViewData["AllPosts"] = posts;
                ViewData["LatestPost"] = Post.FindLastestPost();
                return View();
            }
            return Create();
        }

        // POST: /Blog/
        [AcceptVerbs(HttpVerbs.Post)]
        public ActionResult CreateComment(string Id, FormCollection collection)
        {
            int postId;
            int.TryParse(Id, out postId);
            Post post = Post.Find(postId);

            Comment comment = new Comment();
            comment.Post = post;
            comment.Author = Request.Form["Author"];
            comment.DateAdded = DateTime.Now;
            comment.Text = Request.Form["Comment"];

            comment.Save();

            return Detail(post.Id.ToString());
        }

        // GET: /Blog/Detail/1
        public ActionResult Detail(string Id)
        {
            ViewData["AllPosts"] = Post.FindAll();

            int postId;
            int.TryParse(Id, out postId);

            ViewData["LatestPost"] = Post.Find(postId);

            return View("Index");
        }

        // GET: /Blog/Create
        public ActionResult Create()
        {
            return View("AddPost");
        }

        // POST: /Blog/Create
        [AcceptVerbs(HttpVerbs.Post)]
        public ActionResult Create(FormCollection collection)
        {
            Post post = new Post();
            post.DateAdded = DateTime.Now;
            post.Subject = Request.Form["Subject"];
            post.Text = Request.Form["Content"];
            post.Save();

            return Detail(post.Id.ToString());
        }

        public JsonResult Delete(int id)
        {
            Post post = Post.Find(id);
            IList<int> commentIds = post.Comments.Select(item => item.Id).ToList();
            //先删除评论
            Comment.DeleteAll(commentIds);
            //删除博客
            Post.DeleteAll("Id=" + id);
            return Json(1);
        }

        public JsonResult DeleteComment(int id)
        {
            Comment.DeleteAll("Id="+id);
            return Json(1);
        }
    }
}

关于aspx页面以及webconfig配置的代码请参照源码。

下面对Global.asax文件进行更改：

using System.Configuration;
using System.Web.Mvc;
using System.Web.Routing;
using Castle.ActiveRecord.Framework;
using Terminator.Practice.ActiveRecord.Model;

namespace Terminator.Practice.ActiveRecord.UI.MVC
{
    // Note: For instructions on enabling IIS6 or IIS7 classic mode, 
    // visit http://go.microsoft.com/?LinkId=9394801

    public class MvcApplication : System.Web.HttpApplication
    {
        public static void RegisterRoutes(RouteCollection routes)
        {
            routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

            routes.MapRoute(
                "Default",                                              // Route name
                "{controller}/{action}/{id}",                           // URL with parameters
                new { controller = "Blog", action = "Index", id = "" }  // Parameter defaults
            );

        }

        protected void Application_Start()
        {
            RegisterRoutes(RouteTable.Routes);

            IConfigurationSource source = ConfigurationManager.GetSection("activeRecord") as IConfigurationSource;
            Castle.ActiveRecord.ActiveRecordStarter.Initialize(source, typeof(Post), typeof(Comment));
        }
    }
}

要让Castle ActiveRecord运行起来还需要对webconfig进行配置，下面列出片段:

<configuration>
    <configSections>
        <section name="activeRecord" type="Castle.ActiveRecord.Framework.Config.ActiveRecordSectionHandler, Castle.ActiveRecord"/>
    </configSections>
    <activeRecord isWeb="true">
        <config>
            <add key="hibernate.connection.driver_class" value="NHibernate.Driver.SqlClientDriver"/>
            <add key="dialect" value="NHibernate.Dialect.MsSql2008Dialect"/>
            <add key="hibernate.connection.provider" value="NHibernate.Connection.DriverConnectionProvider"/>
            <add key="connection.connection_string" value="Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Blog.mdf;Integrated Security=True;User Instance=True"/>
            <add key="proxyfactory.factory_class" value="NHibernate.ByteCode.Castle.ProxyFactoryFactory, NHibernate.ByteCode.Castle"/>
        </config>
    </activeRecord>
    <appSettings/>
    <connectionStrings>
        <add name="ApplicationServices" connectionString="data source=.\SQLEXPRESS;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|aspnetdb.mdf;User Instance=true" providerName="System.Data.SqlClient"/>
    </connectionStrings>
.....其他配置内容
</configuration>

关于css和aspx页面的内容这里没有讲的很详细，以下是效果图