.NET7 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.Extensions.DependencyInjection
2.Program.cs中加上
builder.Host.UseServiceProviderFactory(new AutofacServiceProviderFactory()); builder.Host.ConfigureContainer<ContainerBuilder>(containerBuilder => { //在这里写注入代码 });
二、构造函数注入
新建IUserService，类UserService
public interface IUserService { public string GetUserName(); }
public class UserService：IUserService { public string GetUserName() { return "张三"; } }
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();
注入试下是否注入成功
调用成功，证明注入成功
三、属性注入
1.把HomeController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 HomeController : Controller { [AutowiredProperty] private IUserService userService { get; set; } public IActionResult Index() { string name = userService.GetUserName(); return View(); } }
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
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Program.cs中增加
//让控制器实例由容器创建 builder.Services.Replace(ServiceDescriptor.Transient<IControllerActivator, ServiceBasedControllerActivator>());
5.把容器注册到IOC容器，在Program.cs的ConfigureContainer()增加
//获取所有控制器类型并使用属性注入 Type[] controllersTypeAssembly = typeof(Program).Assembly.GetExportedTypes() .Where(type => typeof(ControllerBase).IsAssignableFrom(type)).ToArray(); containerBuilder.RegisterTypes(controllersTypeAssembly).PropertiesAutowired(new AutowiredPropertySelector());
验证：
成功。
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IocManager类
/// <summary> /// Ioc管理 /// </summary> public static class IocManager { /// <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
5.防止Program.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(Program).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,注入Service层的类 builder.BatchAutowired(typeof(UserService).Assembly); //注入其它层的containerBuilder.BatchAutowired(typeof(其它层的任务一个类).Assembly); } }
ConfigureContainer的代码变成
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; } private static IServiceProvider ServiceProvider { 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; ServiceProvider = serviceProvider; } } } } /// <summary> /// 手动获取实例 /// </summary> /// <typeparam name="T"></typeparam> /// <returns></returns> public static T Resolve<T>() { return _container.Resolve<T>(); } /// <summary> /// 手动获取Scope的实例 /// </summary> /// <typeparam name="T"></typeparam> /// <returns></returns> public static T ResolveScope<T>() { if (ServiceProvider == null) { return default(T); } IHttpContextAccessor httpContextAccessor = ServiceProvider.GetRequiredService<IHttpContextAccessor>(); if (httpContextAccessor != null) { return httpContextAccessor.HttpContext.RequestServices.GetService<T>(); } else { return default(T); } }
2.在Program.cs中增加
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(); } }
成功获取到值，证明从容器中获取成功。
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 UserService2 : IUserService { public string GetUserName() { return "张三2号"; } }
