.Net Core MVC 网站开发（Ninesky） 2.3、项目架构调整(续)-使用配置文件动态注入

2021-11-24 00:44:37

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

.Net Core MVC 网站开发（Ninesky） 2.3、项目架构调整(续)-使用配置文件动态注入

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bin\Debug\netcoreapp1.1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。

.Net Core MVC 网站开发（Ninesky） 2.3、项目架构调整(续)-使用配置文件动态注入

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

http://mzwhj.cnblogs.com/

代码包下载：Ninesky2.3、项目架构调整(续)-使用配置文件动态注入.rar

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