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Autofac3 在MVC4中的运用原理
这是一种新的开发模式，注入开发模式，或者叫它IOC模式，说起IOC你可以这样去理解它，它为你的某个实现流出一个注入点，你生产的对象，可以根据你之前的配置进行组合。 IOC全称是Inversion of Control，即反转控制,或者说是依赖注入更为合适。选择别纠结这些全称的专业词。我们可以用别外一些方式去理解它，IOC，是一种设计模式。它的延生所要实现的是把藕合从代码中移出去，统一放到XML文件中，通过一个容器在需要的时候把这个依赖关系形成，即把需要的接口实现注入到需要它的类中，这可能就是“依赖注入”说法的来源了。
而注入点的位置及方式也是多种多样的，我们今天主要说一个通过HTTP请求进行注入的方式，IOC工具使用高效的Autofac,对它的认识你可以看这篇文章。
首先看一下我们这个项目的知识点：
MVC4一个对UI层进行分层的架构模式，在微软的MVC4中加入了开源的Razor引擎
EF（Entity Framework）这无疑是微软自己比较成功的ORM（Object Relational Mapping）工具（即对象关系映射,目前数据库是关系型数据库ORM 主要是把数据库中的关系数据映射称为程序中的对象），它执行效率上要高于linq to sql，甚至你自己编写的ado.net脚本。
Autofac这是在orchard项目中被广泛的IOC工具，它支持类型，反泛，HTTP等注入
对于这个系统的autofac部分，我们将它的注入点放在controller的构造函数中，将生产的对象配置在global中，当然，你也可以设置在config文件，或者你自己的文件中。
我认为它的工作方式应该是：
网站启动=>从global中得到ioc配置信息=>http request请求页面=>通过controller中的参数进行实现的创建=>action中使用创建好的对象
OK，有了这样一个理论基础，我们来看一下代码吧：
EF部分的DATA层
1 public partial class EfRepository<T> : IRepository<T> where T : class 2 { 3 private readonly Guid _instanceId; 4 private readonly IDbContext _context; 5 private IDbSet<T> _entities; 6 public Guid InstanceId 7 { 8 get { return _instanceId; } 9 } 10 public EfRepository(IDbContext context) 11 { 12 AutoCommitEnabled = true; 13 this._context = context; 14 _instanceId = Guid.NewGuid(); 15 } 16 public T GetById(object id) 17 { 18 return this._entities.Find(id); 19 } 20 public T Create() 21 { 22 return this.Entities.Create(); 23 } 24 public void Insert(T entity) 25 { 26 try 27 { 28 if (entity == null) 29 throw new ArgumentNullException("entity"); 30 this.Entities.Add(entity); 31 if (this.AutoCommitEnabled) 32 _context.SaveChanges(); 33 } 34 catch(DbEntityValidationException dbEx) 35 { 36 var msg = string.Empty; 37 foreach(var validationErrors in dbEx.EntityValidationErrors) 38 foreach (var validationError in validationErrors.ValidationErrors) 39 msg += string.Format("Property: {0} Error: {1}", validationError.PropertyName, validationError.ErrorMessage) + Environment.NewLine; 40 var fail = new Exception(msg, dbEx); 41 throw fail; 42 } 43 } 44 45 public void InsertRange(IEnumerable<T> entities, int batchSize = 100) 46 { 47 try 48 { 49 if (entities == null) 50 throw new ArgumentNullException("entities"); 51 if (entities.HasItems()) 52 { 53 if (batchSize <= 0) 54 { 55 entities.Each(x => this.Entities.Add(x)); 56 if (this.AutoCommitEnabled) 57 _context.SaveChanges(); 58 } 59 else 60 { 61 int i = 1; 62 bool saved = false; 63 foreach (var entity in entities) 64 { 65 this.Entities.Add(entity); 66 saved = false; 67 if (i % batchSize == 0) 68 { 69 if (this.AutoCommitEnabled) 70 _context.SaveChanges(); 71 i = 0; 72 saved = true; 73 } 74 i++; 75 } 76 if (!saved) 77 { 78 if (this.AutoCommitEnabled) 79 _context.SaveChanges(); 80 } 81 } 82 } 83 } 84 catch (DbEntityValidationException ex) 85 { 86 throw ex; 87 } 88 } 89 public void Update(T entity) 90 { 91 if (entity == null) 92 throw new ArgumentNullException("entity"); 93 try 94 { 95 if (this.InternalContext.Entry(entity).State == EntityState.Detached) 96 { 97 var set = Entities; 98 T attachedEntity = set.Find(entity.Key); // You need to have access to key 99 100 if (attachedEntity != null)101 {102 var attachedEntry = this.InternalContext.Entry(attachedEntity);103 attachedEntry.CurrentValues.SetValues(entity);104 }105 else106 {107 // This should attach entity108 this.InternalContext.Entry(entity).State = EntityState.Modified;109 }110 }111 }112 finally { }113 114 if (AutoCommitEnabled)115 _context.SaveChanges();116 }117 118 public void Delete(T entity)119 {120 if (entity == null)121 throw new ArgumentNullException("entity");122 if(InternalContext.Entry(entity).State==EntityState.Detached)123 {124 this.Entities.Attach(entity);125 }126 this.Entities.Remove(entity);127 if (this.AutoCommitEnabled)128 _context.SaveChanges();129 }130 131 public IDictionary<string, object> GetModifiedProperties(T entity)132 {133 var props = new Dictionary<string, object>();134 135 var ctx = InternalContext;136 var entry = ctx.Entry(entity);137 var modifiedPropertyNames = from p in entry.CurrentValues.PropertyNames138 where entry.Property(p).IsModified139 select p;140 foreach (var name in modifiedPropertyNames)141 {142 props.Add(name, entry.Property(name).OriginalValue);143 }144 145 return props;146 }147 public virtual IQueryable<T> Table148 {149 get150 {151 return this.Entities;152 }153 }154 155 public int Commit()156 {157 try158 {159 return this._context.SaveChanges();160 }161 catch(DbEntityValidationException dbEx)162 {163 var msg = string.Empty;164 foreach (var validationErrors in dbEx.EntityValidationErrors)165 foreach (var validationError in validationErrors.ValidationErrors)166 msg += Environment.NewLine + string.Format("Property: {0} Error: {1}", validationError.PropertyName, validationError.ErrorMessage);167 168 var fail = new Exception(msg, dbEx);169 throw fail;170 }171 }172 #region Helpers173 protected internal dwDbContextBase InternalContext174 {175 get { return _context as dwDbContextBase; }176 }177 public bool AutoCommitEnabled { get; set; }178 179 private DbSet<T> Entities180 {181 get182 {183 if (_entities == null) { _entities = _context.Set<T>(); }184 return _entities as DbSet<T>;185 }186 }187 188 #endregion189 190 public IQueryable<T> Include(IQueryable<T> query,string path)191 {192 Guard.ArgumentNotNull(query, "query");193 Guard.ArgumentNotEmpty(path, "path");194 return query.Include(path);195 }196 public IQueryable<T> Include<TProperty>(IQueryable<T> query,Expression<Func<T,TProperty>> path)197 {198 Guard.ArgumentNotNull(query, "query");199 Guard.ArgumentNotNull(path, "path");200 return query.Include(path);201 }202 public IDbContext Context203 {204 get { return _context; }205 }206 207 }
Services层（BLL层）核心代码：
1 public class TestService : BaseService, ITestService 2 { 3 private const string IncludeProperties = ""; 4 private readonly IRepository<Tests> _repository; 5 private readonly ICacheManager _cacheManager; 6 private readonly IExporter _exporter; 7 public IList<Tests> GetAll() 8 { 9 return _repository.FindBy(null, null, IncludeProperties).ToList();10 }11 12 public TestService(IRepository<Tests> repository,13 ICacheManager cacheManager,IExporter exporter,14 IEventPublisher eventPublisher):base(eventPublisher)15 {16 _repository = repository;17 _exporter = exporter;18 _cacheManager = cacheManager;19 }20 21 }
WEB层MVC部分代码：(注意：我们的WEB层不应该有对DATA层的引用，WEB层一般只注入SERVICE的对象，这一点是需要注意的，即不要直接调用数据库仓库）
public class TestController : ApiController { private readonly ITestService _service; private readonly Func<Tests, TestsModel, TestsModel> _convertCallback = (entity, model) => { return model; }; public TestController(ITestService service) { _service = service; } public IEnumerable<TestsModel> Get() { var items = _service.GetAll(); var model = items.ConvertTo(_convertCallback); return model; }
而注入参数我们放在global中，看一下核心代码：
//初始化依赖注入组件 var bootStrapper = new AutofacBootStrapper(); BootStrapperManager.Initialize(bootStrapper); //设置依赖注入 GlobalConfiguration.Configuration.DependencyResolver = bootStrapper.GetWebApiDependencyResolver(); DependencyResolver.SetResolver(bootStrapper.GetMvcDependencyResolver());
builder.Register(c => new dwObjectContext("MyConnection")).As<IDbContext>().InstancePerHttpRequest().InstancePerApiRequest(); builder.RegisterGeneric(typeof(EfRepository<>)).As(typeof(IRepository<>)).InstancePerHttpRequest().InstancePerApiRequest(); //注册缓存类型 builder.RegisterType<StaticCache>().As<ICache>().Named<ICache>(YB_CACHE_STATIC).SingleInstance(); builder.RegisterType<RequestCache>().As<ICache>().Named<ICache>(YB_CACHE_PER_REQUEST).InstancePerHttpRequest().InstancePerApiRequest(); //注册缓存控制类型 builder.RegisterType<NullCacheManager>() .As<ICacheManager>() .Named<ICacheManager>(YB_SM_CACHE_NULL) .WithParameter(ResolvedParameter.ForNamed<ICache>(YB_CACHE_STATIC)) .SingleInstance(); builder.RegisterType<DefaultCacheManager>() .As<ICacheManager>() .Named<ICacheManager>(YB_SM_CACHE_PER_REQUEST) .WithParameter(ResolvedParameter.ForNamed<ICache>(YB_CACHE_PER_REQUEST)) .InstancePerHttpRequest().InstancePerApiRequest(); builder.RegisterType<DefaultCacheManager>() .As<ICacheManager>() //.Named<ICacheManager>(YB_SM_CACHE_STATIC) .WithParameter(ResolvedParameter.ForNamed<ICache>(YB_CACHE_STATIC)) .SingleInstance(); var assembly = Assembly.GetExecutingAssembly(); //注册所有 MVC 控制器 builder.RegisterControllers(assembly) .InstancePerHttpRequest(); //注册所有 Web Api 控制器 builder.RegisterApiControllers(assembly) .InstancePerApiRequest();
Autofac3 在MVC4中的运用原理
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