上次实现了依赖注入，但是web项目必须要引用业务逻辑层和数据存储层的实现，项目解耦并不完全；另一方面，要同时注入业务逻辑层和数据访问层，注入的服务直接写在Startup中显得非常臃肿。理想的方式是，web项目近引用接口而不引用实现，在配置文件中进行配置实现程序集合类，注入业务逻辑层而不必注入数据访问层。
一、数据访问层
在项目中摒弃数据访问层或者使用EntityFramework作为数据访问层。
在项目中数据访问层主要实现数据的存储，仔细看一下EntityFramework发现DbContext的功能完全实现了查、增、删、改等各种操作，并且有缓存等功能，本身就实现了仓储模式，并且比自己封装的数据存储层的功能还强大，干脆在项目中用EntityFramework作为数据存储层。删除掉Ninesky.InterfaceDataLibrary项目和Ninesky.DataLibrary项目。
注：项目结构调整的确实太频繁了，以后一段时间内绝不再调整了。
二、实现业务逻辑层。
添加业务逻辑层接口项目Ninesky.InterfaceBase
1、添加接口基类接口InterfaceBaseService，添加基本的查、增、删、改方法
using Ninesky.Models; using System; using System.Linq; using System.Linq.Expressions; namespace Ninesky.InterfaceBase { /// <summary> /// 服务基础接口 /// </summary> public interface InterfaceBaseService<T> where T:class { /// <summary> /// 添加 /// </summary> /// <param name="entity">实体</param> /// <param name="isSave">是否立即保存</param> /// <returns>添加的记录数</returns> int Add(T entity, bool isSave = true); /// <summary> /// 添加[批量] /// </summary> /// <param name="entities">实体</param> /// <param name="isSave">是否立即保存</param> /// <returns>添加的记录数</returns> int AddRange(T[] entities, bool isSave = true); /// <summary> /// 查询记录数 /// </summary> /// <param name="predicate">查询条件</param> /// <returns>记录数</returns> int Count(Expression<Func<T, bool>> predicate); /// <summary> /// 查询是否存在 /// </summary> /// <param name="predicate">查询条件</param> /// <returns>是否存在</returns> bool Exists(Expression<Func<T, bool>> predicate); /// <summary> /// 查找 /// </summary> /// <param name="Id">主键</param> /// <returns></returns> T Find(int Id); /// <summary> /// 查找 /// </summary> /// <param name="keyValues">主键</param> /// <returns></returns> T Find(object[] keyValues); /// <summary> /// 查找 /// </summary> /// <param name="predicate">查询条件</param> /// <returns></returns> T Find(Expression<Func<T, bool>> predicate); IQueryable<T> FindList<TKey>(int number, Expression<Func<T, bool>> predicate); /// <summary> /// 查询 /// </summary> /// <typeparam name="TKey">排序属性</typeparam> /// <param name="number">显示数量[小于等于0-不启用]</param> /// <param name="predicate">查询条件</param> /// <param name="keySelector">排序</param> /// <param name="isAsc">正序</param> /// <returns></returns> IQueryable<T> FindList<TKey>(int number, Expression<Func<T, bool>> predicate, Expression<Func<T, TKey>> keySelector, bool isAsc); /// <summary> /// 查询[分页] /// </summary> /// <typeparam name="TKey">排序属性</typeparam> /// <param name="predicate">查询条件</param> /// <param name="keySelector">排序</param> /// <param name="isAsc">是否正序</param> /// <param name="paging">分页数据</param> /// <returns></returns> Paging<T> FindList<TKey>(Expression<Func<T, bool>> predicate, Expression<Func<T, TKey>> keySelector, bool isAsc, Paging<T> paging); /// <summary> /// 查询[分页] /// </summary> /// <typeparam name="TKey">排序属性</typeparam> /// <param name="predicate">查询条件</param> /// <param name="keySelector">排序</param> /// <param name="isAsc">是否正序</param> /// <param name="pageIndex">当前页</param> /// <param name="pageSize">每页记录数</param> /// <returns></returns> Paging<T> FindList<TKey>(Expression<Func<T, bool>> predicate, Expression<Func<T, TKey>> keySelector, bool isAsc, int pageIndex, int pageSize); /// <summary> /// 删除 /// </summary> /// <param name="entity">实体</param> /// <param name="isSave">是否立即保存</param> /// <returns>是否删除成功</returns> bool Remove(T entity, bool isSave = true); /// <summary> /// 删除[批量] /// </summary> /// <param name="entities">实体数组</param> /// <param name="isSave">是否立即保存</param> /// <returns>成功删除的记录数</returns> int RemoveRange(T[] entities, bool isSave = true); /// <summary> /// 保存到数据库 /// </summary> /// <returns>更改的记录数</returns> int SaveChanges(); /// <summary> /// 更新 /// </summary> /// <param name="entity">实体</param> /// <param name="isSave">是否立即保存</param> /// <returns>是否保存成功</returns> bool Update(T entity, bool isSave = true); /// <summary> /// 更新[批量] /// </summary> /// <param name="entities">实体数组</param> /// <param name="isSave">是否立即保存</param> /// <returns>更新成功的记录数</returns> int UpdateRange(T[] entities, bool isSave = true); } }
2、在Ninesky.Base中添加，接口InterfaceBaseService的实现类BaseService.cs
using Microsoft.EntityFrameworkCore; using Ninesky.InterfaceBase; using Ninesky.Models; using System; using System.Linq; using System.Linq.Expressions; namespace Ninesky.Base { /// <summary> /// 服务基类 /// </summary> public class BaseService<T>:InterfaceBaseService<T> where T:class { protected DbContext _dbContext; public BaseService(DbContext dbContext) { _dbContext = dbContext; } public virtual int Add(T entity, bool isSave = true) { _dbContext.Set<T>().Add(entity); if (isSave) return _dbContext.SaveChanges(); else return 0; } public virtual int AddRange(T[] entities, bool isSave = true) { _dbContext.Set<T>().AddRange(entities); if (isSave) return _dbContext.SaveChanges(); else return 0; } /// <summary> /// 查询记录数 /// </summary> /// <param name="predicate">查询条件</param> /// <returns>记录数</returns> public virtual int Count(Expression<Func<T, bool>> predicate) { return _dbContext.Set<T>().Count(predicate); } /// <summary> /// 查询是否存在 /// </summary> /// <param name="predicate">查询条件</param> /// <returns>是否存在</returns> public virtual bool Exists(Expression<Func<T, bool>> predicate) { return Count(predicate) > 0; } /// <summary> /// 查找 /// </summary> /// <param name="Id">主键</param> /// <returns></returns> public virtual T Find(int Id) { return _dbContext.Set<T>().Find(Id); } public virtual T Find(object[] keyValues) { return _dbContext.Set<T>().Find(keyValues); } public virtual T Find(Expression<Func<T, bool>> predicate) { return _dbContext.Set<T>().SingleOrDefault(predicate); } public virtual IQueryable<T> FindList<TKey>(int number, Expression<Func<T, bool>> predicate) { var entityList = _dbContext.Set<T>().Where(predicate); if (number > 0) return entityList.Take(number); else return entityList; } public virtual IQueryable<T> FindList<TKey>(int number, Expression<Func<T, bool>> predicate, Expression<Func<T, TKey>> keySelector, bool isAsc) { var entityList = _dbContext.Set<T>().Where(predicate); if (isAsc) entityList = entityList.OrderBy(keySelector); else entityList.OrderByDescending(keySelector); if (number > 0) return entityList.Take(number); else return entityList; } public virtual Paging<T> FindList<TKey>(Expression<Func<T, bool>> predicate, Expression<Func<T, TKey>> keySelector, bool isAsc, Paging<T> paging) { var entityList = _dbContext.Set<T>().Where(predicate); paging.Total = entityList.Count(); if (isAsc) entityList = entityList.OrderBy(keySelector); else entityList.OrderByDescending(keySelector); paging.Entities = entityList.Skip((paging.PageIndex - 1) * paging.PageSize).Take(paging.PageSize).ToList(); return paging; } public virtual Paging<T> FindList<TKey>(Expression<Func<T, bool>> predicate, Expression<Func<T, TKey>> keySelector, bool isAsc, int pageIndex, int pageSize) { Paging<T> paging = new Paging<T> { PageIndex = pageIndex, PageSize = pageSize }; return FindList(predicate, keySelector, isAsc, paging); } /// <summary> /// 删除 /// </summary> /// <param name="entity">实体</param> /// <param name="isSave">是否立即保存</param> /// <returns>是否删除成功</returns> public virtual bool Remove(T entity, bool isSave = true) { _dbContext.Set<T>().Remove(entity); if (isSave) return _dbContext.SaveChanges() > 0; else return false; } /// <summary> /// 删除[批量] /// </summary> /// <param name="entities">实体数组</param> /// <param name="isSave">是否立即保存</param> /// <returns>成功删除的记录数</returns> public virtual int RemoveRange(T[] entities, bool isSave = true) { _dbContext.Set<T>().RemoveRange(entities); if (isSave) return _dbContext.SaveChanges(); else return 0; } public virtual int SaveChanges() { return _dbContext.SaveChanges(); } /// <summary> /// 更新 /// </summary> /// <param name="entity">实体</param> /// <param name="isSave">是否立即保存</param> /// <returns>是否保存成功</returns> public virtual bool Update(T entity, bool isSave = true) { _dbContext.Set<T>().Update(entity); if (isSave) return _dbContext.SaveChanges() > 0; else return false; } /// <summary> /// 更新[批量] /// </summary> /// <param name="entities">实体数组</param> /// <param name="isSave">是否立即保存</param> /// <returns>更新成功的记录数</returns> public virtual int UpdateRange(T[] entities, bool isSave = true) { _dbContext.Set<T>().UpdateRange(entities); if (isSave) return _dbContext.SaveChanges(); else return 0; } } }
3、在Ninesky.InterfaceBase项目中添加栏目接口InterfaceCategoryService.cs，新增了一个Findtree的方法
using System; using System.Collections.Generic; using System.Linq; using System.Threading.Tasks; using Ninesky.Models; namespace Ninesky.InterfaceBase { /// <summary> /// 栏目服务接口 /// </summary> public interface InterfaceCategoryService:InterfaceBaseService<Category> { /// <summary> /// 查找树形菜单 /// </summary> /// <param name="categoryType">栏目类型，可以为空</param> /// <returns></returns> List<Category> FindTree(CategoryType? categoryType); } }
4、在Ninesky.Base中添加栏目接口的实现类CategoryService.cs
using System; using System.Collections.Generic; using System.Linq; using System.Threading.Tasks; using Microsoft.EntityFrameworkCore; using Ninesky.Models; using Ninesky.InterfaceBase; namespace Ninesky.Base { /// <summary> /// 栏目服务类 /// </summary> public class CategoryService:BaseService<Category>,InterfaceCategoryService { public CategoryService(DbContext dbContext):base(dbContext) { } /// <summary> /// 查找 /// </summary> /// <param name="Id">栏目ID</param> /// <returns></returns> public override Category Find(int Id) { return _dbContext.Set<Category>().Include("General").Include("Page").Include("Link").SingleOrDefault(c => c.CategoryId == Id); } /// <summary> /// 查找树形菜单 /// </summary> /// <param name="categoryType">栏目类型，可以为空</param> /// <returns></returns> public List<Category> FindTree(CategoryType? categoryType) { var categories = _dbContext.Set<Category>().AsQueryable(); //根据栏目类型分类处理 switch (categoryType) { case null: break; case CategoryType.General: categories = categories.Where(c => c.Type == categoryType); break; //默认-Page或Link类型 default: //Id数组-含本栏目及父栏目 List<int> idArray = new List<int>(); //查找栏目id及父栏目路径 var categoryArray = categories.Where(c => c.Type == categoryType).Select(c => new { CategoryId = c.CategoryId, ParentPath = c.ParentPath }); if(categoryArray != null) { //添加栏目ID到 idArray.AddRange(categoryArray.Select(c => c.CategoryId)); foreach (var parentPath in categoryArray.Select(c=>c.ParentPath)) { var parentIdArray = parentPath.Split(new char[] { ',' }, StringSplitOptions.RemoveEmptyEntries); if (parentIdArray != null) { int parseId = 0; foreach(var parentId in parentIdArray) { if (int.TryParse(parentId, out parseId)) idArray.Add(parseId); } } } } categories = categories.Where(c => idArray.Contains(c.CategoryId)); break; } return categories.OrderBy(c => c.ParentPath).ThenBy(C => C.Order).ToList(); } } }
三、实现dll动态加载和注入
要在web项目中对实现类进行解耦和注入，那么项目只能对接口进行依赖，解除对实现的依赖，然后在配置文件中配置实现的程序集和注入的服务，在Startup类中读取配置文件并加载程序集，然后实现接口的注入。
1、解除实现类依赖
在Web项目中添加对Ninesky.InterfaceBase项目的引用，解除对Ninesky.Base项目的引用。
2、实现注入的配置文件
首先在Models项目中实现注入服务类型配置项ServiceItem
using Microsoft.Extensions.DependencyInjection; using Newtonsoft.Json; using Newtonsoft.Json.Converters; namespace Ninesky.Models { /// <summary> /// 注入服务配置 /// </summary> public class ServiceItem { /// <summary> /// 服务类型[含命名空间] /// </summary> public string ServiceType { get; set; } /// <summary> /// 实现类类型[含命名空间] /// </summary> public string ImplementationType { get; set; } /// <summary> /// 生命周期 /// </summary> [JsonConverter(typeof(StringEnumConverter))] public ServiceLifetime LifeTime { get; set; } } }
然后在Models项目中实现注入需要加载的程序集配置项 AssemblyItem
using System.Collections.Generic; namespace Ninesky.Models { /// <summary> /// 程序集注入项目 /// </summary> public class AssemblyItem { /// <summary> /// 服务的程序集名称[不含后缀] /// </summary> public string ServiceAssembly { get; set; } /// <summary> /// 实现程序集名称[含后缀.dll] /// </summary> public string ImplementationAssembly { get; set; } /// <summary> /// 注入服务集合 /// </summary> public List<ServiceItem> DICollections { get; set; } } }
添加配置文件
在Web项目中添加配置文件service.json
{
"AssemblyCollections": [
{
"ServiceAssembly": "Ninesky.InterfaceBase",
"ImplementationAssembly": "Ninesky.Base.dll",
"DICollections": [
{
"ServiceType": "Ninesky.InterfaceBase.InterfaceCategoryService",
"ImplementationType": "Ninesky.Base.CategoryService",
"LifeTime": "Scoped"
}
]
}
]
}
可以看到配置文件的键值对于AssemblyItem类和ServiceItem类对应。集合的服务程序集为Ninesky.InterfaceBase，实现程序集为Ninesky.Base.dll，注入的服务为Ninesky.InterfaceBase.InterfaceCategoryService，实现类是Ninesky.Base.CategoryService。
读取配置文件并绑定到类型
在Startup只需要一行到即可绑定配置到类型。读取配置文件并绑定的详细操作见《Asp.Net Core自定义配置并绑定》
var assemblyCollections = new ConfigurationBuilder().SetBasePath(Directory.GetCurrentDirectory()).AddJsonFile("service.json").Build().GetSection("AssemblyCollections").Get<List<AssemblyItem>>();
3、进行注入
在assemblyCollections变量加载了配置文件后使用如下代码即可实现注入
foreach(var assembly in assemblyCollections) { var serviceAssembly = Assembly.Load(new AssemblyName(assembly.ServiceAssembly)); var implementationAssembly = AssemblyLoadContext.Default.LoadFromAssemblyPath(AppContext.BaseDirectory + "//" + assembly.ImplementationAssembly); foreach(var service in assembly.DICollections) { services.Add(new ServiceDescriptor(serviceAssembly.GetType(service.ServiceType), implementationAssembly.GetType(service.ImplementationType), service.LifeTime)); } }
代码中可以看到加载接口程序集使用的方法是Assembly.Load(new AssemblyName(assembly.ServiceAssembly))，这是因为项目引用了接口程序集的项目，加载程序集的时候只需要提供程序集的名称就可以。
加载实现类所在程序集的时候使用的是AssemblyLoadContext.Default.LoadFromAssemblyPath(AppContext.BaseDirectory + "//" + assembly.ImplementationAssembly)。在.Net Core中Assembly没有了LoadFrom方法，仅有一个Load方法加载已引用的程序集。多方搜索资料才找到AssemblyLoadContext中有一个方法可以不需要引用项目可以动态加载Dll，但必须包含Dll的完整路径。
到这里就完整实现了解耦，现在项目结构看起来是这样子
解耦后有些麻烦的是修改Base项目的代码后运行项目会出错，必须生成项目后将Base项目生成的Ninesky.Base.dll和Ninesky.Base.pdb复制到Web项目的binDebug etcoreapp1.1目录下才能正常运行。
F5运行一下可以看到正常读出了数据。
四、其他
代码托管地址：https://git.oschina.net/ninesky/Ninesky
文章发布地址：http://www.ninesky.cn