C#基于接口设计三层架构Unity篇
一、引言
面向接口(抽象)编程，是为了降低程序的耦合度，符合依赖倒置原则。因此典型的三层架构UI、BLL、DAL基于接口设计后，会拓展成UI、IBLL、BLL、IDAL、DAL。在上一篇《C# IoC学习笔记》中我们可以了解到，控制反转(IoC)使对象的创建交给了第三方IoC容器如Unity。利用Unity的IoC功能，可以对基于接口设计的三层架构做进一步的升级，搭建一个更容易实现的可配置可扩展的三层架构；利用Unity的AOP功能，使框架更加的简洁，因为它抽出了框架的公共逻辑部分。
二、项目建立
2.1、项目建立
依次新建项目UI(Client)、IBLL、BLL、IDAL、DAL、Model、Common。
2.2项目说明
三、项目之间的引用关系
3.1、对着项目名称右键->添加->引用->项目，添加各个项目的引用。
3.2、引用说明
四、项目需安装的NuGet包
五、注意事项
对Unity容器的IoC调用进行封装，Container应封装成单例模式以提高效率，此处使用MemoryCache。
5.1、在Common项目引用System.Runtime.Caching.dll，并在Helper文件夹下新建一个缓存帮助类：MemoryCacheHelper.cs。
/// <summary> /// 内存缓存帮助类，支持绝对过期时间、滑动过期时间、文件依赖三种缓存方式。 /// </summary> class MemoryCacheHelper { private static readonly object _locker1 = new object(), _locker2 = new object(); /// <summary> /// 取缓存项，如果不存在则返回空。 /// </summary> /// <typeparam name="T"></typeparam> /// <param name="key"></param> /// <returns></returns> public static T GetCacheItem<T>(string key) { try { return (T)MemoryCache.Default[key]; } catch { return default(T); } } /// <summary> /// 是否包含指定键的缓存项 /// </summary> /// <param name="key"></param> /// <returns></returns> public static bool Contains(string key) { return MemoryCache.Default.Contains(key); } /// <summary> /// 取缓存项，如果不存在则新增缓存项。 /// </summary> /// <typeparam name="T"></typeparam> /// <param name="key"></param> /// <param name="cachePopulate"></param> /// <param name="slidingExpiration"></param> /// <param name="absoluteExpiration"></param> /// <returns></returns> public static T GetOrAddCacheItem<T>(string key, Func<T> cachePopulate, TimeSpan? slidingExpiration = null, DateTime? absoluteExpiration = null) { if (string.IsNullOrWhiteSpace(key)) throw new ArgumentException("Invalid cache key"); if (cachePopulate == null) throw new ArgumentNullException("cachePopulate"); if (slidingExpiration == null && absoluteExpiration == null) throw new ArgumentException("Either a sliding expiration or absolute must be provided"); if (MemoryCache.Default[key] == null) { lock (_locker1) { if (MemoryCache.Default[key] == null) { T cacheValue = cachePopulate(); if (!typeof(T).IsValueType && cacheValue == null) //如果是引用类型且为NULL则不存缓存 { return cacheValue; } var item = new CacheItem(key, cacheValue); var policy = CreatePolicy(slidingExpiration, absoluteExpiration); MemoryCache.Default.Add(item, policy); } } } return (T)MemoryCache.Default[key]; } /// <summary> /// 取缓存项，如果不存在则新增缓存项。 /// </summary> /// <typeparam name="T"></typeparam> /// <param name="key"></param> /// <param name="cachePopulate"></param> /// <param name="dependencyFilePath"></param> /// <returns></returns> public static T GetOrAddCacheItem<T>(string key, Func<T> cachePopulate, string dependencyFilePath) { if (string.IsNullOrWhiteSpace(key)) throw new ArgumentException("Invalid cache key"); if (cachePopulate == null) throw new ArgumentNullException("cachePopulate"); if (MemoryCache.Default[key] == null) { lock (_locker2) { if (MemoryCache.Default[key] == null) { T cacheValue = cachePopulate(); if (!typeof(T).IsValueType && cacheValue == null) //如果是引用类型且为NULL则不存缓存 { return cacheValue; } var item = new CacheItem(key, cacheValue); var policy = CreatePolicy(dependencyFilePath); MemoryCache.Default.Add(item, policy); } } } return (T)MemoryCache.Default[key]; } /// <summary> /// 指定缓存项的一组逐出和过期详细信息 /// </summary> /// <param name="slidingExpiration"></param> /// <param name="absoluteExpiration"></param> /// <returns></returns> private static CacheItemPolicy CreatePolicy(TimeSpan? slidingExpiration, DateTime? absoluteExpiration) { var policy = new CacheItemPolicy(); if (absoluteExpiration.HasValue) { policy.AbsoluteExpiration = absoluteExpiration.Value; } else if (slidingExpiration.HasValue) { policy.SlidingExpiration = slidingExpiration.Value; } policy.Priority = CacheItemPriority.Default; return policy; } /// <summary> /// 指定缓存项的一组逐出和过期详细信息 /// </summary> /// <param name="filePath"></param> /// <returns></returns> private static CacheItemPolicy CreatePolicy(string filePath) { CacheItemPolicy policy = new CacheItemPolicy(); policy.ChangeMonitors.Add(new HostFileChangeMonitor(new List<string>() { filePath })); policy.Priority = CacheItemPriority.Default; return policy; } /// <summary> /// 移除指定键的缓存项 /// </summary> /// <param name="key"></param> public static void RemoveCacheItem(string key) { if (Contains(key)) { MemoryCache.Default.Remove(key); } } }
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5.2、在Common项目Helper文件夹下面新建一个Unity帮助类：UnityHelper.cs，并实现Container的缓存。
/// <summary> /// Unity容器帮助类 /// </summary> public static class UnityHelper { /// <summary> /// Unity容器创建对象(不含别名) /// </summary> /// <param name="containerName">容器名称</param> /// <returns></returns> public static T GetObject<T>(string containerName) { IUnityContainer container = MemoryCacheHelper.GetOrAddCacheItem(containerName, () => { IUnityContainer unityContainer = new UnityContainer(); ExeConfigurationFileMap fileMap = new ExeConfigurationFileMap { ExeConfigFilename = Path.Combine(AppDomain.CurrentDomain.BaseDirectory + @"ConfigFiles\Unity.config") }; Configuration configuration = ConfigurationManager.OpenMappedExeConfiguration(fileMap, ConfigurationUserLevel.None); UnityConfigurationSection configSection = (UnityConfigurationSection)configuration.GetSection(UnityConfigurationSection.SectionName); configSection.Configure(unityContainer, containerName); return unityContainer; },TimeSpan.FromMinutes(30),null); return container.Resolve<T>(); } /// <summary> /// Unity容器创建对象(含别名) /// </summary> /// <typeparam name="T"></typeparam> /// <param name="containerName">容器名称</param> /// <param name="alisName">对象别名</param> /// <returns></returns> public static T GetObject<T>(string containerName, string alisName) { IUnityContainer container = MemoryCacheHelper.GetOrAddCacheItem(containerName, () => { IUnityContainer unityContainer = new UnityContainer(); ExeConfigurationFileMap fileMap = new ExeConfigurationFileMap { ExeConfigFilename = Path.Combine(AppDomain.CurrentDomain.BaseDirectory + @"ConfigFiles\Unity.config") }; Configuration configuration = ConfigurationManager.OpenMappedExeConfiguration(fileMap, ConfigurationUserLevel.None); UnityConfigurationSection configSection = (UnityConfigurationSection)configuration.GetSection(UnityConfigurationSection.SectionName); configSection.Configure(unityContainer, containerName); return unityContainer; }, TimeSpan.FromMinutes(30), null); return container.Resolve<T>(alisName); } }
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