net core天马行空系列：原生DI+AOP实现spring boot注解式编程
写过spring boot之后，那种无处不在的注解让我非常喜欢，比如属性注入@autowire，配置值注入@value，声明式事物@Transactional等，都非常简洁优雅，那么我就在想，这些在net core里能实现么？经过一番摸索，终于实现并整理成此文。
IOC方面，个人非常喜欢net core自带的DI，因为他注册服务简洁优雅，3个生命周期通俗易懂，所以就没使用autofac等其他容器，AOP方面，使用了业内鼎鼎大名的Castle.DynamicProxy(简称DP),所以要在nuget中添加Castle.Core的依赖包，这里大家可能会有疑问，利用mvc的actionFilter不就可以实现了么，为什么还要引用DP呢，因为呀，actionFilter只在controller层有效，普通类他就无能为力了，而DP无所不能。
1.定义注解和需要用到的类
属性注入注解
[AttributeUsage(AttributeTargets.Property)] public class AutowiredAttribute : Attribute { }
配置值注入注解
[AttributeUsage(AttributeTargets.Property)] public class ValueAttribute : Attribute { public ValueAttribute(string value = "") { this.Value = value; } public string Value { get; } }
声明式事物注解
[AttributeUsage(AttributeTargets.Method)] public class TransactionalAttribute : Attribute { }
工作单元接口及实现类，用来实现事物操作，注入级别为scope，一次请求公用一个工作单元实例
public interface IUnitOfWork : IDisposable { /// <summary> /// 开启事务 /// </summary> void BeginTransaction(); /// <summary> /// 提交 /// </summary> void Commit(); /// <summary> /// 事物回滚 /// </summary> void RollBack(); }
public class UnitOfWork : IUnitOfWork { public void BeginTransaction() { Console.WriteLine("开启事务"); } public void Commit() { Console.WriteLine("提交事务"); } public void Dispose() { //throw new System.NotImplementedException(); } public void RollBack() { Console.WriteLine("回滚事务"); } }
拦截器
/// <summary> /// 事物拦截器 /// </summary> public class TransactionalInterceptor : StandardInterceptor { private IUnitOfWork Uow { set; get; } public TransactionalInterceptor(IUnitOfWork uow) { Uow = uow; } protected override void PreProceed(IInvocation invocation) { Console.WriteLine("{0}拦截前", invocation.Method.Name); var method = invocation.TargetType.GetMethod(invocation.Method.Name); if (method != null && method.GetCustomAttribute<TransactionalAttribute>() != null) { Uow.BeginTransaction(); } } protected override void PerformProceed(IInvocation invocation) { invocation.Proceed(); } protected override void PostProceed(IInvocation invocation) { Console.WriteLine("{0}拦截后， 返回值是{1}", invocation.Method.Name, invocation.ReturnValue); var method = invocation.TargetType.GetMethod(invocation.Method.Name); if (method != null && method.GetCustomAttribute<TransactionalAttribute>() != null) { Uow.Commit(); } } }
用来测试注入效果的接口以及实现类，这里我们定义一辆汽车，汽车拥有一个引擎（属性注入），它能点火启动，点火操作带事物，这里为了演示【接口-实现类】注入和【实现类】注入2种情况，引擎就没添加接口，只有实现类，并且AOP拦截仅有【实现类】的类时，只能拦截虚方法，所以Start和Stop函数为虚函数。
/// <summary> /// 汽车引擎 /// </summary> public class Engine { [Value("HelpNumber")] public string HelpNumber { set; get; } public virtual void Start() { Console.WriteLine("发动机启动"); Stop(); } public virtual void Stop() { Console.WriteLine("发动机熄火,拨打求救电话" + HelpNumber); } }
public interface ICar { Engine Engine { set; get; } void Fire(); }
public class Car : ICar { [Autowired] public Engine Engine { set; get; } [Value("oilNo")] public int OilNo { set; get; } [Transactional] public void Fire() { Console.WriteLine("加满" + OilNo + "号汽油,点火"); Engine.Start(); } }
控制器HomeController
public class HomeController : Controller { [Autowired] public ICar Car{ set; get; } [Value("description")] public string Description { set; get; } public IActionResult Index() { var car = Car; Console.WriteLine(Description); Car.Fire(); return View(); } }
修改appsettings.json，添加一些测试键值对，（如果测试时发现输出的中文乱码，把appsettings.json保存为utf8格式即可），具体代码如下，
{ "Logging": { "LogLevel": { "Default": "Warning" } }, "AllowedHosts": "*", "oilNo": 95, "HelpNumber": "110", "description": "我要开始飙车了" }
2.效果图
从上图可以看到，正常注入，正常开启拦截器和事务，正确读取配置值。
从上图可以看到，我们的控制器，ICar和Engine全部都是动态代理类，注入正常。
3.核心代码
第一部分，添加一个扩展类，名叫SummerBootExtentions.cs，代码如下
public static class SummerBootExtentions { /// <summary> /// 瞬时 /// </summary> /// <typeparam name="TService"></typeparam> /// <typeparam name="TImplementation"></typeparam> /// <param name="services"></param> /// <param name="interceptorTypes"></param> /// <returns></returns> public static IServiceCollection AddSbTransient<TService, TImplementation>(this IServiceCollection services, params Type[] interceptorTypes) { return services.AddSbService(typeof(TService), typeof(TImplementation), ServiceLifetime.Transient, interceptorTypes); } /// <summary> /// 请求级别 /// </summary> /// <typeparam name="TService"></typeparam> /// <typeparam name="TImplementation"></typeparam> /// <param name="services"></param> /// <param name="interceptorTypes"></param> /// <returns></returns> public static IServiceCollection AddSbScoped<TService, TImplementation>(this IServiceCollection services, params Type[] interceptorTypes) { return services.AddSbService(typeof(TService), typeof(TImplementation), ServiceLifetime.Scoped, interceptorTypes); } /// <summary> /// 单例 /// </summary> /// <typeparam name="TService"></typeparam> /// <typeparam name="TImplementation"></typeparam> /// <param name="services"></param> /// <param name="interceptorTypes"></param> /// <returns></returns> public static IServiceCollection AddSbSingleton<TService, TImplementation>(this IServiceCollection services, params Type[] interceptorTypes) { return services.AddSbService(typeof(TService), typeof(TImplementation), ServiceLifetime.Singleton, interceptorTypes); } public static IServiceCollection AddSbService(this IServiceCollection services, Type serviceType, Type implementationType, ServiceLifetime lifetime, params Type[] interceptorTypes) { services.Add(new ServiceDescriptor(implementationType, implementationType, lifetime)); object Factory(IServiceProvider provider) { var target = provider.GetService(implementationType); var properties = implementationType.GetTypeInfo().DeclaredProperties; foreach (PropertyInfo info in properties) { //属性注入 if (info.GetCustomAttribute<AutowiredAttribute>() != null) { var propertyType = info.PropertyType; var impl = provider.GetService(propertyType); if (impl != null) { info.SetValue(target, impl); } } //配置值注入 if (info.GetCustomAttribute<ValueAttribute>() is ValueAttribute valueAttribute) { var value = valueAttribute.Value; if (provider.GetService(typeof(IConfiguration)) is IConfiguration configService) { var pathValue = configService.GetSection(value).Value; if (pathValue != null) { var pathV = Convert.ChangeType(pathValue, info.PropertyType); info.SetValue(target, pathV); } } } } List<IInterceptor> interceptors = interceptorTypes.ToList() .ConvertAll<IInterceptor>(interceptorType => provider.GetService(interceptorType) as IInterceptor); var proxy = new ProxyGenerator().CreateInterfaceProxyWithTarget(serviceType, target, interceptors.ToArray()); return proxy; }; var serviceDescriptor = new ServiceDescriptor(serviceType, Factory, lifetime); services.Add(serviceDescriptor); return services; } /// <summary> /// 瞬时 /// </summary> /// <typeparam name="TService"></typeparam> /// <param name="services"></param> /// <param name="interceptorTypes"></param> /// <returns></returns> public static IServiceCollection AddSbTransient<TService>(this IServiceCollection services, params Type[] interceptorTypes) { return services.AddSbService(typeof(TService), ServiceLifetime.Transient, interceptorTypes); } /// <summary> /// 请求 /// </summary> /// <typeparam name="TService"></typeparam> /// <param name="services"></param> /// <param name="interceptorTypes"></param> /// <returns></returns> public static IServiceCollection AddSbScoped<TService>(this IServiceCollection services, params Type[] interceptorTypes) { return services.AddSbService(typeof(TService), ServiceLifetime.Scoped, interceptorTypes); } /// <summary> /// 单例 /// </summary> /// <typeparam name="TService"></typeparam> /// <param name="services"></param> /// <param name="interceptorTypes"></param> /// <returns></returns> public static IServiceCollection AddSbSingleton<TService>(this IServiceCollection services, params Type[] interceptorTypes) { return services.AddSbService(typeof(TService), ServiceLifetime.Singleton, interceptorTypes); } public static IServiceCollection AddSbService(this IServiceCollection services, Type serviceType, ServiceLifetime lifetime, params Type[] interceptorTypes) { if (services == null) throw new ArgumentNullException(nameof(services)); if (serviceType == (Type)null) throw new ArgumentNullException(nameof(serviceType)); object Factory(IServiceProvider provider) { List<IInterceptor> interceptors = interceptorTypes.ToList() .ConvertAll<IInterceptor>(interceptorType => provider.GetService(interceptorType) as IInterceptor); var proxy = new ProxyGenerator().CreateClassProxy(serviceType, interceptors.ToArray()); var properties = serviceType.GetTypeInfo().DeclaredProperties; foreach (PropertyInfo info in properties) { //属性注入 if (info.GetCustomAttribute<AutowiredAttribute>() != null) { var propertyType = info.PropertyType; var impl = provider.GetService(propertyType); if (impl != null) { info.SetValue(proxy, impl); } } //配置值注入 if (info.GetCustomAttribute<ValueAttribute>() is ValueAttribute valueAttribute) { var value = valueAttribute.Value; if (provider.GetService(typeof(IConfiguration)) is IConfiguration configService) { var pathValue = configService.GetSection(value).Value; if (pathValue != null) { var pathV = Convert.ChangeType(pathValue, info.PropertyType); info.SetValue(proxy, pathV); } } } } return proxy; }; var serviceDescriptor = new ServiceDescriptor(serviceType, Factory, lifetime); services.Add(serviceDescriptor); return services; } /// <summary> /// 添加summer boot扩展 /// </summary> /// <param name="builder"></param> /// <returns></returns> public static IMvcBuilder AddSB(this IMvcBuilder builder) { if (builder == null) throw new ArgumentNullException(nameof(builder)); ControllerFeature feature = new ControllerFeature(); builder.PartManager.PopulateFeature<ControllerFeature>(feature); foreach (Type type in feature.Controllers.Select<TypeInfo, Type>((Func<TypeInfo, Type>)(c => c.AsType()))) builder.Services.TryAddTransient(type, type); builder.Services.Replace(ServiceDescriptor.Transient<IControllerActivator, SbControllerActivator>()); return builder; } }
第二部分，添加一个自定义控制器激活类，用以替换掉mvc自带的激活类，这个类命名为SbControllerActivator.cs，代码如下
public class SbControllerActivator : IControllerActivator { /// <inheritdoc /> public object Create(ControllerContext actionContext) { if (actionContext == null) throw new ArgumentNullException(nameof(actionContext)); Type serviceType = actionContext.ActionDescriptor.ControllerTypeInfo.AsType(); var target = actionContext.HttpContext.RequestServices.GetRequiredService(serviceType); var properties = serviceType.GetTypeInfo().DeclaredProperties; var proxy = new ProxyGenerator().CreateClassProxyWithTarget(serviceType, target); foreach (PropertyInfo info in properties) { //属性注入 if (info.GetCustomAttribute<AutowiredAttribute>() != null) { var propertyType = info.PropertyType; var impl = actionContext.HttpContext.RequestServices.GetService(propertyType); if (impl != null) { info.SetValue(proxy, impl); } } //配置值注入 if (info.GetCustomAttribute<ValueAttribute>() is ValueAttribute valueAttribute) { var value = valueAttribute.Value; if (actionContext.HttpContext.RequestServices.GetService(typeof(IConfiguration)) is IConfiguration configService) { var pathValue = configService.GetSection(value).Value; if (pathValue != null) { var pathV = Convert.ChangeType(pathValue, info.PropertyType); info.SetValue(proxy, pathV); } } } } return proxy; } /// <inheritdoc /> public virtual void Release(ControllerContext context, object controller) { } }
第三部分，在Startup.cs中，修改ConfigureServices方法如下
public void ConfigureServices(IServiceCollection services) { services.Configure<CookiePolicyOptions>(options => { // This lambda determines whether user consent for non-essential cookies is needed for a given request. options.CheckConsentNeeded = context => true; options.MinimumSameSitePolicy = SameSiteMode.None; }); services.AddMvc() .SetCompatibilityVersion(CompatibilityVersion.Version_2_1) .AddSB(); services.AddSbScoped<Engine>(typeof(TransactionalInterceptor)); services.AddScoped<IUnitOfWork,UnitOfWork>(); services.AddScoped(typeof(TransactionalInterceptor)); services.AddSbScoped<ICar, Car>(typeof(TransactionalInterceptor)); }
从上面代码我们可以看到，在addMvc后加上了我们替换默认控制器的AddSB方法，接管了控制器的生成。AddSbScoped<Engine>和AddSbScoped<ICar, Car>这种添加依赖注入的方式也保持了net core自带DI的原滋原味，简洁优雅，并且实现了动态代理，只需要在参数里添加拦截器，就能实时拦截，这里参数为params Type[],可以添加N个拦截器。
4.写在最后
在博客园潜水了好几年，见证了net core从1.0到快出3.0，这也是第一次尝试着写博客，为net core的发扬光大尽自己的一份力。
