在 上一篇 中将项目的基本骨架搭起来能正常跑通，这一篇将讲到，如何通过autofac将DbContext和model进行解耦，只用添加model，而不用在DbContext中添加DbSet。
在这里就不详细讲autofac是干什么用的了，简单说下autofac。
1.autofac可替换net core自带的DI IOC，用来扩展。
2.autofac可提供Aop，具体实现在博客园有很多示例。
3.autofac的几个生命周期用法：InstancePerDependency 每次都创建一个对象 ，SingleInstance 每次都是同一个对象，InstancePerLifetimeScope 同一个生命周期生成的对象是同一个。
接下来，我们需要在启动项目上通过nuget安装两个Package：Autofac、Autofac.Extensions.DependencyInjection。
因为autofac是通过接口来进行注入的，因此我们需要创建对应的基层接口用来注入。在basic项目通过nuget安装Autofac.Extensions.DependencyInjection、，
然后中添加 Dependency 文件夹来存放基层接口，添加IOC容器接口：IIocManager，代码如下：
using System;
using Autofac;
using Autofac.Core; namespace DemoFrame_Basic.Dependency
{
/// <summary>
/// IOC容器接口
/// </summary>
public interface IIocManager
{
IContainer Container { get; } bool IsRegistered(Type serviceType, ILifetimeScope scope = null);
object Resolve(Type type, ILifetimeScope scope = null);
T Resolve<T>(string key = "", ILifetimeScope scope = null) where T : class;
T Resolve<T>(params Parameter[] parameters) where T : class;
T[] ResolveAll<T>(string key = "", ILifetimeScope scope = null);
object ResolveOptional(Type serviceType, ILifetimeScope scope = null);
object ResolveUnregistered(Type type, ILifetimeScope scope = null);
T ResolveUnregistered<T>(ILifetimeScope scope = null) where T : class;
ILifetimeScope Scope();
bool TryResolve(Type serviceType, ILifetimeScope scope, out object instance);
}
}
-IOC容器接口
再添加一个数据库基础接口：IEntityBase
/// <summary>
/// 数据库基础接口
/// </summary>
public interface IEntityBase
{
}
-数据库基础接口
IIocManager的实现类：IocManager
using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Runtime.Loader;
using Autofac;
using Autofac.Core;
using Autofac.Core.Lifetime;
using Autofac.Extensions.DependencyInjection;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.DependencyModel; namespace DemoFrame_Basic.Dependency
{
/// <summary>
/// Container manager
/// </summary>
public class IocManager : IIocManager
{
private IContainer _container; public static IocManager Instance { get { return SingletonInstance; } }
private static readonly IocManager SingletonInstance = new IocManager(); /// <summary>
/// Ioc容器初始化
/// </summary>
/// <param name="config"></param>
/// <returns></returns>
public IServiceProvider Initialize(IServiceCollection services)
{ //.InstancePerDependency() //每次都创建一个对象
//.SingleInstance() //每次都是同一个对象
//.InstancePerLifetimeScope() //同一个生命周期生成的对象是同一个 var builder = new ContainerBuilder();
builder.RegisterInstance(Instance).As<IIocManager>().SingleInstance();
//所有程序集 和程序集下类型
var deps = DependencyContext.Default;
var libs = deps.CompileLibraries.Where(lib => !lib.Serviceable && lib.Type != "package");//排除所有的系统程序集、Nuget下载包
var listAllType = new List<Type>();
foreach (var lib in libs)
{
try
{
var assembly = AssemblyLoadContext.Default.LoadFromAssemblyName(new AssemblyName(lib.Name));
listAllType.AddRange(assembly.GetTypes().Where(type => type != null));
}
catch { }
} //注册IEntityBase实现类
var entityBaseType = typeof(IEntityBase);
var arrEntityBaseType = listAllType.Where(t => entityBaseType.IsAssignableFrom(t) && t != entityBaseType).ToArray();
builder.RegisterTypes(arrEntityBaseType)
.AsImplementedInterfaces()
.SingleInstance()
.PropertiesAutowired(); foreach (var type in arrEntityBaseType)
{
if (type.IsClass && !type.IsAbstract && !type.BaseType.IsInterface && type.BaseType != typeof(object))
{
builder.RegisterType(type).As(type.BaseType)
.SingleInstance()
.PropertiesAutowired();
}
} //注册controller实现类 让Controller能被找到
var controller = typeof(ControllerBase);
var arrcontrollerType = listAllType.Where(t => controller.IsAssignableFrom(t) && t != controller).ToArray();
builder.RegisterTypes(arrcontrollerType)
.AsImplementedInterfaces()
.SingleInstance()
.PropertiesAutowired(); foreach (var type in arrcontrollerType)
{
if (type.IsClass && !type.IsAbstract && !type.BaseType.IsInterface && type.BaseType != typeof(object))
{
builder.RegisterType(type).AsSelf();
}
} builder.Populate(services);
_container = builder.Build();
return new AutofacServiceProvider(_container);
} /// <summary>
/// Gets a container
/// </summary>
public virtual IContainer Container
{
get
{
return _container;
}
} /// <summary>
/// Resolve
/// </summary>
/// <typeparam name="T">Type</typeparam>
/// <param name="key">key</param>
/// <param name="scope">Scope; pass null to automatically resolve the current scope</param>
/// <returns>Resolved service</returns>
public virtual T Resolve<T>(string key = "", ILifetimeScope scope = null) where T : class
{
if (scope == null)
{
//no scope specified
scope = Scope();
}
if (string.IsNullOrEmpty(key))
{
return scope.Resolve<T>();
}
return scope.ResolveKeyed<T>(key);
} /// <summary>
/// Resolve
/// </summary>
/// <typeparam name="T">Type</typeparam>
/// <param name="key">key</param>
/// <param name="scope">Scope; pass null to automatically resolve the current scope</param>
/// <returns>Resolved service</returns>
public virtual T Resolve<T>(params Parameter[] parameters) where T : class
{
var scope = Scope();
return scope.Resolve<T>(parameters);
} /// <summary>
/// Resolve
/// </summary>
/// <param name="type">Type</param>
/// <param name="scope">Scope; pass null to automatically resolve the current scope</param>
/// <returns>Resolved service</returns>
public virtual object Resolve(Type type, ILifetimeScope scope = null)
{
if (scope == null)
{
//no scope specified
scope = Scope();
}
return scope.Resolve(type);
} /// <summary>
/// Resolve all
/// </summary>
/// <typeparam name="T">Type</typeparam>
/// <param name="key">key</param>
/// <param name="scope">Scope; pass null to automatically resolve the current scope</param>
/// <returns>Resolved services</returns>
public virtual T[] ResolveAll<T>(string key = "", ILifetimeScope scope = null)
{
if (scope == null)
{
//no scope specified
scope = Scope();
}
if (string.IsNullOrEmpty(key))
{
return scope.Resolve<IEnumerable<T>>().ToArray();
}
return scope.ResolveKeyed<IEnumerable<T>>(key).ToArray();
} /// <summary>
/// Resolve unregistered service
/// </summary>
/// <typeparam name="T">Type</typeparam>
/// <param name="scope">Scope; pass null to automatically resolve the current scope</param>
/// <returns>Resolved service</returns>
public virtual T ResolveUnregistered<T>(ILifetimeScope scope = null) where T : class
{
return ResolveUnregistered(typeof(T), scope) as T;
} /// <summary>
/// Resolve unregistered service
/// </summary>
/// <param name="type">Type</param>
/// <param name="scope">Scope; pass null to automatically resolve the current scope</param>
/// <returns>Resolved service</returns>
public virtual object ResolveUnregistered(Type type, ILifetimeScope scope = null)
{
if (scope == null)
{
//no scope specified
scope = Scope();
}
var constructors = type.GetConstructors();
foreach (var constructor in constructors)
{
try
{
var parameters = constructor.GetParameters();
var parameterInstances = new List<object>();
foreach (var parameter in parameters)
{
var service = Resolve(parameter.ParameterType, scope);
if (service == null) throw new Exception("Unknown dependency");
parameterInstances.Add(service);
}
return Activator.CreateInstance(type, parameterInstances.ToArray());
}
catch (Exception)
{ }
}
throw new Exception("No constructor was found that had all the dependencies satisfied.");
} /// <summary>
/// Try to resolve srevice
/// </summary>
/// <param name="serviceType">Type</param>
/// <param name="scope">Scope; pass null to automatically resolve the current scope</param>
/// <param name="instance">Resolved service</param>
/// <returns>Value indicating whether service has been successfully resolved</returns>
public virtual bool TryResolve(Type serviceType, ILifetimeScope scope, out object instance)
{
if (scope == null)
{
//no scope specified
scope = Scope();
}
return scope.TryResolve(serviceType, out instance);
} /// <summary>
/// Check whether some service is registered (can be resolved)
/// </summary>
/// <param name="serviceType">Type</param>
/// <param name="scope">Scope; pass null to automatically resolve the current scope</param>
/// <returns>Result</returns>
public virtual bool IsRegistered(Type serviceType, ILifetimeScope scope = null)
{
if (scope == null)
{
//no scope specified
scope = Scope();
}
return scope.IsRegistered(serviceType);
} /// <summary>
/// Resolve optional
/// </summary>
/// <param name="serviceType">Type</param>
/// <param name="scope">Scope; pass null to automatically resolve the current scope</param>
/// <returns>Resolved service</returns>
public virtual object ResolveOptional(Type serviceType, ILifetimeScope scope = null)
{
if (scope == null)
{
//no scope specified
scope = Scope();
}
return scope.ResolveOptional(serviceType);
} /// <summary>
/// Get current scope
/// </summary>
/// <returns>Scope</returns>
public virtual ILifetimeScope Scope()
{
try
{
//when such lifetime scope is returned, you should be sure that it'll be disposed once used (e.g. in schedule tasks)
return Container.BeginLifetimeScope();
}
catch (Exception)
{
//we can get an exception here if RequestLifetimeScope is already disposed
//for example, requested in or after "Application_EndRequest" handler
//but note that usually it should never happen //when such lifetime scope is returned, you should be sure that it'll be disposed once used (e.g. in schedule tasks)
return Container.BeginLifetimeScope(MatchingScopeLifetimeTags.RequestLifetimeScopeTag);
}
}
}
}
-Container manager
在这里添加完以后，我们需要将自带的DI容器给替换成现在使用的autofac，
在启动项目的Startup文件中更改，最终代码如下：
public IServiceProvider ConfigureServices(IServiceCollection services)
{
services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1); services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>(); services.Replace(ServiceDescriptor.Transient<IControllerActivator, ServiceBasedControllerActivator>()); services.AddDbContext<DemoDbContext>(options => options.UseSqlServer(Configuration.GetConnectionString("SqlServerConnection"))); return IocManager.Instance.Initialize(services);
}
-ConfigureServices
为了方便使用，在CoreMvc项目中添加DemoWeb的类来存放一些系统数据：
using DemoFrame_Basic.Dependency;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Caching.Memory;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Hosting;
using System.Linq; namespace DemoFrame_CoreMvc
{
public class DemoWeb
{
private static IHttpContextAccessor _httpContextAccessor; /// <summary>
/// Configure
/// </summary>
/// <param name="httpContextAccessor"></param>
public static void Configure(IHttpContextAccessor httpContextAccessor)
{
_httpContextAccessor = httpContextAccessor;
} /// <summary>
/// 当前请求HttpContext
/// </summary>
public static HttpContext HttpContext
{
get => _httpContextAccessor.HttpContext;
set => _httpContextAccessor.HttpContext = value;
} /// <summary>
/// IocManager
/// </summary>
public static IIocManager IocManager { get; set; } /// <summary>
/// Environment
/// </summary>
public static IHostingEnvironment Environment { get; set; } /// <summary>
/// Configuration
/// </summary>
public static IConfiguration Configuration { get; set; } /// <summary>
/// MemoryCache
/// </summary>
public static IMemoryCache MemoryCache { get; set; } /// <summary>
/// 获取当前请求客户端IP
/// </summary>
/// <returns></returns>
public static string GetClientIp()
{
var ip = HttpContext.Request.Headers["X-Forwarded-For"].FirstOrDefault()?.Split(',')[].Trim();
if (string.IsNullOrEmpty(ip))
{
ip = HttpContext.Connection.RemoteIpAddress.ToString();
}
return ip;
}
}
}
Startup的完整代码如下：
public class Startup
{
public Startup(IConfiguration configuration)
{
DemoWeb.Configuration = configuration;
Configuration = configuration;
} public IConfiguration Configuration { get; } // This method gets called by the runtime. Use this method to add services to the container.
public IServiceProvider ConfigureServices(IServiceCollection services)
{
services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1); services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>(); services.Replace(ServiceDescriptor.Transient<IControllerActivator, ServiceBasedControllerActivator>()); services.AddDbContext<DemoDbContext>(options => options.UseSqlServer(Configuration.GetConnectionString("SqlServerConnection"))); return IocManager.Instance.Initialize(services);
} // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
DemoWeb.IocManager = app.ApplicationServices.GetService<IIocManager>();
DemoWeb.Environment = env;
try//注意这里在本地开发允许时会重置数据库，并清空所有数据，如不需要请注释
{
if (env.IsDevelopment())
{
using (var serviceScope = app.ApplicationServices.GetRequiredService<IServiceScopeFactory>()
.CreateScope())
{
var dbContent = serviceScope.ServiceProvider.GetService<DemoDbContext>();
//CheckMigrations(dbContent);
var database = serviceScope.ServiceProvider.GetService<DemoDbContext>().Database;
database.EnsureDeleted();
database.EnsureCreated();
}
}
}
catch (Exception ex)
{
//LogHelper.Logger.Error(ex, "Failed to migrate or seed database");
}
DemoWeb.Configure(app.ApplicationServices.GetRequiredService<IHttpContextAccessor>());
if (env.IsDevelopment())
{
app.UseDeveloperExceptionPage();
}
else
{
app.UseHsts();
}
app.UseCors(builder => builder.AllowAnyOrigin().AllowAnyHeader().AllowAnyMethod().AllowCredentials());//允许跨域
app.UseHttpsRedirection();
app.UseMvc();
} }
-Startup
在这么多的配置都完成了的情况下，我们该去实现mode与DbContext的解耦操作了。那么该如何做呢？
废话不多说了，直接上代码，在数据库上下文DemoDbContext中将之前的DbSet删掉，更改如下：
！！！先将之前的model都继承 IEntityBase 接口。这样在模型生成时才能生成到数据库！！！
/// <summary>
/// 数据库上下文
/// </summary>
public class DemoDbContext : DbContext
{
public DemoDbContext(DbContextOptions<DemoDbContext> options)
: base(options)
{ } #region IOC得到所有实体
private readonly IEntityBase[] _entitys = DemoWeb.IocManager.ResolveAll<IEntityBase>();
#endregion protected override void OnModelCreating(ModelBuilder modelBuilder)
{
if (_entitys == null)
{
return;
}
foreach (var entity in _entitys)
{
modelBuilder.Model.AddEntityType(entity.GetType());
}
}
}
-数据库上下文
在使用数据库上下文是，使用Set<T>方法设置需要使用的的类
在下一篇中将介绍如何使用基类controller来统一前后端交互数据，统一使用一个模型进行返回。
有需要源码的可通过此 GitHub链接拉取 觉得还可以的给个 start 哦，谢谢！