.NET平臺依賴注入機(jī)制及IoC的設(shè)計與實現(xiàn)(2)_.Net教程

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推薦：基于.NET平臺的分層架構(gòu)實戰(zhàn)(五)接口的設(shè)計與實現(xiàn)
接下來，將進(jìn)行接口的設(shè)計。這里包括數(shù)據(jù)訪問層接口和業(yè)務(wù)邏輯層接口。在分層架構(gòu)中，接口扮演著非常重要的角色，它不但直接決定了各層中的各個操作類需要實現(xiàn)何種操作，而且它明確了各個層次的

封裝依賴注入代碼
因為很多依賴注入代碼非常相似，為了減少重復(fù)性代碼，我們將可復(fù)用的代碼先封裝在一個類中。具體代碼如下（這個類放在Factory工程下）：

using System;
using System.Configuration;
using System.Reflection;
using System.Web;
using System.Web.Caching;
using NGuestBook.Utility;

namespace NGuestBook.Factory
{
/**//// <summary>
/// 依賴注入提供者
/// 使用反射機(jī)制實現(xiàn)
/// </summary>
public sealed class DependencyInjector
{
/**//// <summary>
/// 取得數(shù)據(jù)訪問層對象
/// 首先檢查緩存中是否存在，如果不存在，則利用反射機(jī)制返回對象
/// </summary>
/// <param name="className">數(shù)據(jù)訪問類名稱</param>
/// <returns>數(shù)據(jù)訪問層對象</returns>
public static object GetDALObject(string className)
{
/**//// <summary>
/// 取得數(shù)據(jù)訪問層名稱，首先檢查緩存，不存在則到配置文件中讀取
/// 緩存依賴項為Web.Config文件
/// </summary>
object dal = CacheAccess.GetFromCache("DAL");
if (dal == null)
{
CacheDependency fileDependency = new CacheDependency(HttpContext.Current.Server.MapPath("Web.Config"));
dal = ConfigurationManager.AppSettings["DAL"];
CacheAccess.SaveToCache("DAL", dal, fileDependency);
}

/**//// <summary>
/// 取得數(shù)據(jù)訪問層對象
/// </summary>
string dalName = (string)dal;
string fullClassName = dalName "." className;
object dalObject = CacheAccess.GetFromCache(className);
if (dalObject == null)
{
CacheDependency fileDependency = new CacheDependency(HttpContext.Current.Server.MapPath("Web.Config"));
dalObject = Assembly.Load(dalName).CreateInstance(fullClassName);
CacheAccess.SaveToCache(className, dalObject, fileDependency);
}

return dalObject;
}

/**//// <summary>
/// 取得業(yè)務(wù)邏輯層對象
/// 首先檢查緩存中是否存在，如果不存在，則利用反射機(jī)制返回對象
/// </summary>
/// <param name="className">業(yè)務(wù)邏輯類名稱</param>
/// <returns>業(yè)務(wù)邏輯層對象</returns>
public static object GetBLLObject(string className)
{
/**//// <summary>
/// 取得業(yè)務(wù)邏輯層名稱，首先檢查緩存，不存在則到配置文件中讀取
/// 緩存依賴項為Web.Config文件
/// </summary>
object bll = CacheAccess.GetFromCache("BLL");
if (bll == null)
{
CacheDependency fileDependency = new CacheDependency(HttpContext.Current.Server.MapPath("Web.Config"));
bll = ConfigurationManager.AppSettings["BLL"];
CacheAccess.SaveToCache("BLL", bll, fileDependency);
}

/**//// <summary>
/// 取得業(yè)務(wù)邏輯層對象
/// </summary>
string bllName = (string)bll;
string fullClassName = bllName "." className;
object bllObject = CacheAccess.GetFromCache(className);
if (bllObject == null)
{
CacheDependency fileDependency = new CacheDependency(HttpContext.Current.Server.MapPath("Web.Config"));
bllObject = Assembly.Load(bllName).CreateInstance(fullClassName);
CacheAccess.SaveToCache(className, bllObject, fileDependency);
}

return bllObject;
}
}
}

實現(xiàn)工廠
下面使用兩個輔助類，實現(xiàn)數(shù)據(jù)訪問層工廠和業(yè)務(wù)邏輯層工廠。

using System;
using NGuestBook.IDAL;

namespace NGuestBook.Factory
{
/**//// <summary>
/// 數(shù)據(jù)訪問層工廠，用于獲取相應(yīng)的數(shù)據(jù)訪問層對象
/// 使用Abstract Factory設(shè)計模式 Facace設(shè)計模式反射機(jī)制緩存機(jī)制設(shè)計
/// </summary>
public sealed class DALFactory
{
/**//// <summary>
/// 獲取管理員數(shù)據(jù)訪問層對象
/// </summary>
/// <returns>管理員數(shù)據(jù)訪問層對象</returns>
public static IAdminDAL CreateAdminDAL()
{
return (IAdminDAL)DependencyInjector.GetDALObject("AdminDAL");
}
/**//// <summary>
/// 獲取留言數(shù)據(jù)訪問層對象
/// </summary>
/// <returns>留言數(shù)據(jù)訪問層對象</returns>
public static IMessageDAL CreateMessageDAL()
{
return (IMessageDAL)DependencyInjector.GetDALObject("MessageDAL");
}

/**//// <summary>
/// 獲取評論數(shù)據(jù)訪問層對象
/// </summary>
/// <returns>評論數(shù)據(jù)訪問層對象</returns>
public static ICommentDAL CreateCommentDAL()
{
return (ICommentDAL)DependencyInjector.GetDALObject("CommentDAL");
}
}
}

using System;
using NGuestBook.IBLL;

namespace NGuestBook.Factory
{
/**//// <summary>
/// 業(yè)務(wù)邏輯層工廠，用于獲取相應(yīng)的業(yè)務(wù)邏輯層對象
/// 使用Abstract Factory設(shè)計模式 Facace設(shè)計模式反射機(jī)制緩存機(jī)制設(shè)計
/// </summary>
public sealed class BLLFactory
{
/**//// <summary>
/// 獲取管理員業(yè)務(wù)邏輯層對象
/// </summary>
/// <returns>管理員業(yè)務(wù)邏輯層對象</returns>
public static IAdminBLL CreateAdminBLL()
{
return (IAdminBLL)DependencyInjector.GetBLLObject("AdminBLL");
}

/**//// <summary>
/// 獲取留言業(yè)務(wù)邏輯層對象
/// </summary>
/// <returns>留言業(yè)務(wù)邏輯層對象</returns>
public static IMessageBLL CreateMessageBLL()
{
return (IMessageBLL)DependencyInjector.GetBLLObject("MessageBLL");
}

/**//// <summary>
/// 獲取評論業(yè)務(wù)邏輯層對象
/// </summary>
/// <returns>評論業(yè)務(wù)邏輯層對象</returns>
public static ICommentBLL CreateCommentBLL()
{
return (ICommentBLL)DependencyInjector.GetBLLObject("CommentBLL");
}
}
}

分享：基于.NET平臺的分層架構(gòu)實戰(zhàn)(四)實體類的設(shè)計與實現(xiàn)
實體類是現(xiàn)實實體在計算機(jī)中的表示。它貫穿于整個架構(gòu)，負(fù)擔(dān)著在各層次及模塊間傳遞數(shù)據(jù)的職責(zé)。一般來說，實體類可以分為“貧血實體類”和“充血實體類”，前者僅僅保存實