.Net Core5.0中Autofac依赖注入整合多层，项目中可直接用
一、配置Autofac替换内置DI
1.安装Nuget包：Autofac，Autofac.Extensions.DependencyInjection
2.Program.cs中CreateHostBuilder方法后加上.UseServiceProviderFactory(new AutofacServiceProviderFactory()) ; 告诉程序要使用Autofac。
3.Startup.cs中增加方法ConfigureContainer(ContainerBuilder containerBuilder)，实例注入的地方，配置完成。
/// <summary> /// Autofac注册服务的地方,Autofac会自动调用 /// </summary> /// <param name="containerBuilder"></param> public void ConfigureContainer(ContainerBuilder containerBuilder) { }
二、构造函数注入
新建IUserService，类UserService，控制器UserController
public interface IUserService { public string GetUserName(); }
public class UserService { public string GetUserName() { return "张三"; } }
public class UserController : Controller { private readonly IUserService _userService; public UserController(IUserService userService) { _userService = userService; } public IActionResult Index() { string name = _userService.GetUserName(); return Content(name); } }
在上面的ConfigureContainer方法把UserService注入进来，默认是瞬时注入
瞬时注入：containerBuilder.RegisterType<UserService>().As<IUserService>().InstancePerDependency();;
单例注入：containerBuilder.RegisterType<UserService>().As<IUserService>().SingleInstance();
生命周期注入： containerBuilder.RegisterType<UserService>().As<IUserService>().InstancePerLifetimeScope();
/// <summary> /// Autofac注册服务的地方,Autofac会自动调用 /// </summary> /// <param name="containerBuilder"></param> public void ConfigureContainer(ContainerBuilder containerBuilder) { //注册服务 containerBuilder.RegisterType<UserService>().As<IUserService>(); }
访问/User/Index，_userService成功注入，正确获取结果。
三、属性注入
1.把UserController改成属性注入形式，属性注入有一个问题，就是那些属性需要注入？全部注入没必要，父类也有很多属性，要按需注入，给属性增加一个自定义特性标识说明需要注入。
public class UserController : Controller { [AutowiredProperty] private IUserService userService { get; set; } public IActionResult Index() { string name = userService.GetUserName(); return Content(name); } }
2.新增自定义特性类AutowiredPropertyAttribute.cs
[AttributeUsage(AttributeTargets.Property)]//为了支持属性注入，只能打到属性上 public class AutowiredPropertyAttribute : Attribute { }
3.增加识别特性类AutowiredPropertySelector.cs
/// <summary> /// IPropertySelector:查看属性上是否标记某一个特性 /// </summary> public class AutowiredPropertySelector : IPropertySelector { public bool InjectProperty(PropertyInfo propertyInfo, object instance) { //判断属性的特性是否包含自定义的属性,标记有返回true return propertyInfo.CustomAttributes.Any(s => s.AttributeType == typeof(AutowiredPropertyAttribute)); } }
4.因为Controller 默认是由 Mvc 模块管理的，需要把控制器放到IOC容器中，在Startup.cs的ConfigureServices中增加
//让控制器实例由容器创建 services.Replace(ServiceDescriptor.Transient<IControllerActivator, ServiceBasedControllerActivator>());
5.把容器注册到IOC容器，在Startup.cs的ConfigureContainer()增加
//获取所有控制器类型并使用属性注入 Type[] controllersTypeAssembly = typeof(Startup).Assembly.GetExportedTypes() .Where(type => typeof(ControllerBase).IsAssignableFrom(type)).ToArray(); containerBuilder.RegisterTypes(controllersTypeAssembly).PropertiesAutowired(new AutowiredPropertySelector());
6.验证结果，新增一个接口IOrderService.cs和一个实现类OrderService.cs做对比
public interface IOrderService { public string CreateOrder(); } public class OrderService : IOrderService { public string CreateOrder() { return "下单成功"; } }
把UserController改成
public class UserController : Controller { [AutowiredProperty] private IUserService userService { get; set; } private IOrderService orderService { get; set; }//不加属性注入标识 public IActionResult Index() { string name = userService.GetUserName(); return Content(name); } }
注入方法ConfigureContainer()增加
containerBuilder.RegisterType<OrderService>().As<IOrderService>();
运行程序，能看到增加了注入标识的userService注入成功，没加标识的orderService没有注入。
四、批量注入
实际项目中那么多需要注入的类，一个个写注册就不太现实了，需要一个可以批量注入的方法。
1.新建三个空接口IScopeDenpendency.cs，ISingletonDenpendency.cs，ITransitDenpendency.cs
/// <summary> /// 瞬时注入 /// </summary> public interface ITransitDenpendency { } /// <summary> /// 单例注入标识 /// </summary> public interface ISingletonDenpendency { } /// <summary> /// 生命周期注入标识 /// </summary> public interface IScopeDenpendency { }
2.把上面要注入的类实现上面的接口
3.新增一个IocManger类
/// <summary> /// 批量注入扩展 /// </summary> /// <param name="builder"></param> /// <param name="assembly"></param> public static void BatchAutowired(this ContainerBuilder builder, Assembly assembly) { var transientType = typeof(ITransitDenpendency); //瞬时注入 var singletonType = typeof(ISingletonDenpendency); //单例注入 var scopeType = typeof(IScopeDenpendency); //单例注入 //瞬时注入 builder.RegisterAssemblyTypes(assembly).Where(t => t.IsClass && !t.IsAbstract && t.GetInterfaces().Contains(transientType)) .AsSelf() .AsImplementedInterfaces() .InstancePerDependency() .PropertiesAutowired(new AutowiredPropertySelector()); //单例注入 builder.RegisterAssemblyTypes(assembly).Where(t => t.IsClass && !t.IsAbstract && t.GetInterfaces().Contains(singletonType)) .AsSelf() .AsImplementedInterfaces() .SingleInstance() .PropertiesAutowired(new AutowiredPropertySelector()); //生命周期注入 builder.RegisterAssemblyTypes(assembly).Where(t => t.IsClass && !t.IsAbstract && t.GetInterfaces().Contains(scopeType)) .AsSelf() .AsImplementedInterfaces() .InstancePerLifetimeScope() .PropertiesAutowired(new AutowiredPropertySelector()); }
4.把注入类ConfigureContainer改成
/// <summary> /// Autofac注册服务的地方,Autofac会自动调用 /// </summary> /// <param name="containerBuilder"></param> public void ConfigureContainer(ContainerBuilder containerBuilder) { //获取所有控制器类型并使用属性注入 Type[] controllersTypeAssembly = typeof(Startup).Assembly.GetExportedTypes() .Where(type => typeof(ControllerBase).IsAssignableFrom(type)).ToArray(); containerBuilder.RegisterTypes(controllersTypeAssembly).PropertiesAutowired(new AutowiredPropertySelector()); //批量自动注入,把需要注入层的程序集传参数 containerBuilder.BatchAutowired(typeof(UserService).Assembly); containerBuilder.BatchAutowired(typeof(UserRepository).Assembly); }
5.防止startup.cs代码过多，建一个Module把注入代码搬走，新建AutofacRegisterModule.cs类把ConfigureContainer的代码移过去
public class AutofacRegisterModule:Autofac.Module { protected override void Load(ContainerBuilder builder) { //获取所有控制器类型并使用属性注入 Type[] controllersTypeAssembly = typeof(Startup).Assembly.GetExportedTypes() .Where(type => typeof(ControllerBase).IsAssignableFrom(type)).ToArray(); builder.RegisterTypes(controllersTypeAssembly).PropertiesAutowired(new AutowiredPropertySelector()); //批量自动注入,把需要注入层的程序集传参数 builder.BatchAutowired(typeof(UserService).Assembly); builder.BatchAutowired(typeof(UserRepository).Assembly); } }
ConfigureContainer的代码变成
/// <summary> /// Autofac注册服务的地方,Autofac会自动调用 /// </summary> /// <param name="containerBuilder"></param> public void ConfigureContainer(ContainerBuilder containerBuilder) { containerBuilder.RegisterModule<AutofacRegisterModule>(); }
五、手动获取实例
手动获取实例的场景有静态帮助类中获取实例，例如redisHelper中获取注入的配置文件中的连接字符串
1.在上面的IocManager类中增加
private static object obj = new object(); private static ILifetimeScope _container { get; set; } public static void InitContainer(ILifetimeScope container) { //防止过程中方法被调用_container发生改变 if (_container == null) { lock (obj) { if (_container == null) { _container = container; } } } } /// <summary> /// 手动获取实例 /// </summary> /// <typeparam name="T"></typeparam> /// <returns></returns> public static T Resolve<T>() { return _container.Resolve<T>(); }
2.在Startup.cs的Configure()中增加
//获取Autofac容器上下文信息
IocManager.InitContainer(app.ApplicationServices.GetAutofacRoot());
3.验证，新建一个DataHelper.cs类
public class DataHelper { //手动注入UserService private static IUserService userService = IocManager.Resolve<IUserService>(); public static string GetData() { return userService.GetUserName(); } }
修改UserController用DataHelper的方法成功获取数据
六、其它用法
1.不用接口，直接注入实例
public class UserService :ITransitDenpendency { public string GetUserName() { return "张三"; } }
2.一接口多实现
public class UserService :IUserService { public string GetUserName() { return "张三"; } } public class User2Service : IUserService { public string GetUserName() { return "张三2号"; } }
最后：源码地址：https://github.com/weixiaolong325/.NetCore5.0AutofacDemo
演示项目结构：
