说在前
Ioc组件有很多，之前也介绍过autofac,castle等，今天再来说一下在微软Nlayer DDD架构里使用的unity组件，今天主要说一下依靠注入，如果希望看拦截的用法，可以阅读这篇文章第十三回 实现AOP的拦截组件Unity.Interception
做在后
unity的用法主要说一下接口注入方法，它包括了程序中注入和配置文件注入，而接口注入还分为普通接口注入和泛型接口注入，下面分别来说一下：
普通接口和类实现代码
public interface IUser { IQueryable<WebManageUsers> GetEntities(); } public class UserRepository : BackgroundRepository<WebManageUsers>, IUser { public IQueryable<WebManageUsers> GetEntities() { return this.GetModel(); } }
普通接口注入，程序中的注入
using (IUnityContainer container = new UnityContainer()) { container.RegisterType<IUser, DataTest.UserRepository>(); var repository = container.Resolve<IUser>(); }
普通接口注入，配置文件中的注入
<unity xmlns="http://schemas.microsoft.com/practices/2010/unity"> <container> <register type="EntityTest.IUser,EntityTest" mapTo="DataTest.UserRepository, DataTest" /> </container> </unity>
using (IUnityContainer container = new UnityContainer()) { ConfigurationManager.GetSection("unity"); UnityConfigurationSection.CurrentSection.Configure(container); var repository = container.Resolve<IUser>(); }
普通接口和类实现代码
/// <summary> /// 基础的数据操作规范 /// </summary> /// <typeparam name="TEntity"></typeparam> public interface IRepository<TEntity> where TEntity : class { /// <summary> /// 添加实体并提交到数据服务器 /// </summary> /// <param name="item">Item to add to repository</param> void Insert(TEntity item); /// <summary> /// 移除实体并提交到数据服务器 /// 如果表存在约束，需要先删除子表信息 /// </summary> /// <param name="item">Item to delete</param> void Delete(TEntity item); /// <summary> /// 修改实体并提交到数据服务器 /// </summary> /// <param name="item"></param> void Update(TEntity item); /// <summary> /// 得到指定的实体集合（延时结果集） /// Get all elements of type {T} in repository /// </summary> /// <returns>List of selected elements</returns> IQueryable<TEntity> GetModel(); /// <summary> /// 根据主键得到实体 /// </summary> /// <param name="id"></param> /// <returns></returns> TEntity Find(params object[] id); } public class BackgroundRepository<T> : IRepository<T> where T : class { #region IRepository<TEntity> 成员 public virtual void Insert(TEntity item) { OnBeforeSaved(new SavedEventArgs(item, SaveAction.Insert)); Db.Entry<TEntity>(item); Db.Set<TEntity>().Add(item); this.SaveChanges(); OnAfterSaved(new SavedEventArgs(item, SaveAction.Insert)); } public virtual void Delete(TEntity item) { OnBeforeSaved(new SavedEventArgs(item, SaveAction.Delete)); Db.Set<TEntity>().Attach(item); Db.Set<TEntity>().Remove(item); this.SaveChanges(); OnAfterSaved(new SavedEventArgs(item, SaveAction.Delete)); } public virtual void Update(TEntity item) { OnBeforeSaved(new SavedEventArgs(item, SaveAction.Update)); Db.Set<TEntity>().Attach(item); Db.Entry(item).State = EntityState.Modified; this.SaveChanges(); OnAfterSaved(new SavedEventArgs(item, SaveAction.Update)); } /// <summary> /// 子类在实现时，可以重写，加一些状态过滤 /// </summary> /// <returns></returns> public virtual IQueryable<TEntity> GetModel() { // return Db.Set<TEntity>().AsNoTracking();//对象无法自动添加到上下文中，因为它是使用 NoTracking 合并选项检索的。请在定义此关系之前，将该实体显式附加到 ObjectContext。 return Db.Set<TEntity>();////ObjectStateManager 中已存在具有同一键的对象。ObjectStateManager 无法跟踪具有相同键的多个对象。 } /// <summary> /// 得到原生态结果集 /// </summary> /// <returns></returns> public IQueryable<TEntity> GetEntities() { return Db.Set<TEntity>(); } #endregion
｝
泛型接口注入，程序中的注入
using (IUnityContainer container = new UnityContainer()) { container.RegisterType<IRepository<User>, BackgroundRepository<User>>(); var re = container.Resolve<IRepository<User>>(); }
泛型接口注入，配置文件中的注入
<unity xmlns="http://schemas.microsoft.com/practices/2010/unity"> <container> <register type="IRepository.Core.IRepository`1,IRepository.Core" mapTo="DataTest.BackgroundRepository`1, DataTest" /> </container> </unity>
using (IUnityContainer container = new UnityContainer()) { ConfigurationManager.GetSection("unity"); UnityConfigurationSection.CurrentSection.Configure(container); var re = container.Resolve<IRepository<User>>(); }
下面我们封装一个服务定位器，让它把Unity容器封装一下，方便以后调用它，下面是ServiceLocator的原代码：
/// <summary> /// Represents the Service Locator. /// </summary> public sealed class ServiceLocator : IServiceProvider { #region Private Fields private readonly IUnityContainer _container; #endregion #region Private Static Fields private static readonly ServiceLocator instance = new ServiceLocator(); #endregion #region Ctor /// <summary> /// Initializes a new instance of ServiceLocator class. /// </summary> private ServiceLocator() { UnityConfigurationSection section = (UnityConfigurationSection)ConfigurationManager.GetSection("unity"); _container = new UnityContainer(); section.Configure(_container); } #endregion #region Public Static Properties /// <summary> /// Gets the singleton instance of the ServiceLocator class. /// </summary> public static ServiceLocator Instance { get { return instance; } } #endregion #region Private Methods private IEnumerable<ParameterOverride> GetParameterOverrides(object overridedArguments) { List<ParameterOverride> overrides = new List<ParameterOverride>(); Type argumentsType = overridedArguments.GetType(); argumentsType.GetProperties(BindingFlags.Public | BindingFlags.Instance) .ToList() .ForEach(property => { var propertyValue = property.GetValue(overridedArguments, null); var propertyName = property.Name; overrides.Add(new ParameterOverride(propertyName, propertyValue)); }); return overrides; } #endregion #region Public Methods /// <summary> /// Gets the service instance with the given type. /// </summary> /// <typeparam name="T">The type of the service.</typeparam> /// <returns>The service instance.</returns> public T GetService<T>() { return _container.Resolve<T>(); } /// <summary> /// Gets the service instance with the given type by using the overrided arguments. /// </summary> /// <typeparam name="T">The type of the service.</typeparam> /// <param name="overridedArguments">The overrided arguments.</param> /// <returns>The service instance.</returns> public T GetService<T>(object overridedArguments) { var overrides = GetParameterOverrides(overridedArguments); return _container.Resolve<T>(overrides.ToArray()); } /// <summary> /// Gets the service instance with the given type by using the overrided arguments. /// </summary> /// <param name="serviceType">The type of the service.</param> /// <param name="overridedArguments">The overrided arguments.</param> /// <returns>The service instance.</returns> public object GetService(Type serviceType, object overridedArguments) { var overrides = GetParameterOverrides(overridedArguments); return _container.Resolve(serviceType, overrides.ToArray()); } #endregion #region IServiceProvider Members /// <summary> /// Gets the service instance with the given type. /// </summary> /// <param name="serviceType">The type of the service.</param> /// <returns>The service instance.</returns> public object GetService(Type serviceType) { return _container.Resolve(serviceType); } #endregion }
下面再去使用unity时就方便多了，呵呵，看代码：
var model = ServiceLocator.Instance.GetService<IExtensionRepository<WebManageUsers>>().GetModel().ToList();
而使用ServiceLocator还有一个好处，就是不需要使用＂实现的程序集＂，只要把＂实现的程序集＂和它的相关依赖的程序集一起复制到ＷＥＢ项目的ＢＩＮ目录即可，服务定位器会自己去定位的．
好了，讲到这里也就差不多了，需要注意的是，如果你在项目中进行注入时，需要先注入的实现类所在的程序集也引入进来，否则也是不可以resolve出来对象的，而对于业务层（领域）层来说，不需要关心底层
的实现技术，即不需要引用实现类的程序集，而在业务层引用接口程序集即可．
本文转自博客园张占岭（仓储大叔）的博客，原文链接：我心中的核心组件（可插拔的AOP）~第十二回 IoC组件Unity，如需转载请自行联系原博主。
