ABP之动态WebAPI(一)

ABP的动态WebApi实现了直接对服务层的调用（其实病没有跨过ApiController,只是将ApiController公共化，对于这一点的处理类似于MVC，对服务端的调用没有跨过HttpHandler一样），这样不仅减少了ApiController的开发，也更能体现驱动领域设计的层结构。

对WebApi服务的替换与路由配置

AbpWebApiModule是Abp.Web.Api的模块类，该类中定义InitializeAspNetServices，InitializeRoutes两个方法，并且在模块的Initialize方法中执行，这两个方法分别是对WebApi的服务的替换与路由的配置，。这两处对WebApi的变更才使得直接调用服务层成为可能。

        private static void InitializeAspNetServices()
        {
            GlobalConfiguration.Configuration.Services.Replace(typeof(IHttpControllerSelector), new AbpHttpControllerSelector(GlobalConfiguration.Configuration));
            GlobalConfiguration.Configuration.Services.Replace(typeof(IHttpActionSelector), new AbpApiControllerActionSelector());
            GlobalConfiguration.Configuration.Services.Replace(typeof(IHttpControllerActivator), new AbpControllerActivator());
        }

        private static void InitializeRoutes()
        {
            DynamicApiRouteConfig.Register();
        }

        public static void Register()
        {
            //Dynamic Web APIs (with area name)
            GlobalConfiguration.Configuration.Routes.MapHttpRoute(
                name: "AbpDynamicWebApi",
                routeTemplate: "api/services/{*serviceNameWithAction}"
                );
        }

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对服务的分析与缓存

再对服务信息的存储上，作者提供了DynamicApiControllerInfo，DynamicApiActionInfo（源码中的DynamicApiMethodInfo.cs），其中DynamicApiControllerInfo包含了一DynamicApiActionInfo集合。

    internal class DynamicApiControllerInfo
    {
        /// <summary>
        /// Name of the service.
        /// </summary>
        public string ServiceName { get; private set; }

        /// <summary>
        /// Controller type.
        /// </summary>
        public Type Type { get; private set; }

        /// <summary>
        /// Dynamic Action Filters for this controller.
        /// </summary>
        public IFilter[] Filters { get; set; }

        /// <summary>
        /// All actions of the controller.
        /// </summary>
        public IDictionary<string, DynamicApiActionInfo> Actions { get; private set; }

        /// <summary>
        /// Creates a new <see cref="DynamicApiControllerInfo"/> instance.
        /// </summary>
        /// <param name="serviceName">Name of the service</param>
        /// <param name="type">Controller type</param>
        /// <param name="filters">Filters</param>
        public DynamicApiControllerInfo(string serviceName, Type type, IFilter[] filters = null)
        {
            ServiceName = serviceName;
            Type = type;
            Filters = filters ?? new IFilter[] { }; //Assigning or initialzing the action filters.

            Actions = new Dictionary<string, DynamicApiActionInfo>(StringComparer.InvariantCultureIgnoreCase);
        }
    }

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在执行AbpHttpControllerSelector, AbpApiControllerActionSelector, AbpControllerActivator的时候，系统已经在初始化的时候对服务层进行了分析与缓存。

在作者给的Demo SimpleTaskSystem下有一模块类SimpleTaskSystemWebApiModule

[DependsOn(typeof(AbpWebApiModule))] //We declare depended modules explicitly
public class SimpleTaskSystemWebApiModule : AbpModule
{
    public override void Initialize()
    {
        //This code is used to register classes to dependency injection system for this assembly using conventions.
        IocManager.RegisterAssemblyByConvention(Assembly.GetExecutingAssembly());
 
        //Creating dynamic Web Api Controllers for application services.
        //Thus, 'web api layer' is created automatically by ABP.
 
        DynamicApiControllerBuilder
            .ForAll<IApplicationService>(Assembly.GetAssembly(typeof (SimpleTaskSystemApplicationModule)), "tasksystem")
            .Build();
    }
}

在这里是使用到了DynamicApiControllerBuilder，这个类主要是对服务接口进行一个注册，再由IBatchApiControllerBuilder按照注册的服务接口对提供的程序集进行分析。

DynamicApiControllerBuilder提供的ForAll只是返回的一个IBatchApiControllerBuilder实现对象

public static IBatchApiControllerBuilder<T> ForAll<T>(Assembly assembly, string servicePrefix)
{
    return new BatchApiControllerBuilder<T>(assembly, servicePrefix);
}

这个方法为BatchApiControllerBuilder提供了服务接口与服务接口与需要分析的程序集，以及服务地址前缀。

BatchApiControllerBuilder从程序集中获取实现服务接口的非抽象类。BatchApiControllerBuilder再通过DynamicApiControllerBuilder将这些类与服务名信息传递给IApiControllerBuilder。

public void Build()
{
    var types =
        from
            type in _assembly.GetTypes()
        where
            type.IsPublic && type.IsInterface && typeof(T).IsAssignableFrom(type) && IocManager.Instance.IsRegistered(type)
        select
            type;
 
    if (_typePredicate != null)
    {
        types = types.Where(t => _typePredicate(t));
    }
 
    foreach (var type in types)
    {
        var serviceName = _serviceNameSelector != null
            ? _serviceNameSelector(type)
            : GetConventionalServiceName(type);
 
        if (!string.IsNullOrWhiteSpace(_servicePrefix))
        {
            serviceName = _servicePrefix + "/" + serviceName;
        }
 
        var builder = typeof(DynamicApiControllerBuilder)
            .GetMethod("For", BindingFlags.Public | BindingFlags.Static)
            .MakeGenericMethod(type)
            .Invoke(null, new object[] { serviceName });
 
        if (_filters != null)
        {
            builder.GetType()
                .GetMethod("WithFilters", BindingFlags.Public | BindingFlags.Instance)
                .Invoke(builder, new object[] { _filters });
        }
 
        builder.GetType()
                .GetMethod("Build", BindingFlags.Public | BindingFlags.Instance)
                .Invoke(builder, new object[0]);
    }
}

IApiControllerBuilder将通过服务类生成DynamicApiControllerInfo，再将IApiControllerBuilder存储于DynamicApiControllerManager中，同时分析服务类，将公开非静态方法作为action，存储到DynamicApiControllerManager.Actions

internal class ApiControllerBuilder<T> : IApiControllerBuilder<T>
{
    /// <summary>
    /// Name of the controller.
    /// </summary>
    private readonly string _serviceName;
 
    /// <summary>
    /// List of all action builders for this controller.
    /// </summary>
    private readonly IDictionary<string, ApiControllerActionBuilder<T>> _actionBuilders;
 
    /// <summary>
    /// Action Filters to apply to the whole Dynamic Controller.
    /// </summary>
    private IFilter[] _filters;
 
    /// <summary>
    /// Creates a new instance of ApiControllerInfoBuilder.
    /// </summary>
    /// <param name="serviceName">Name of the controller</param>
    public ApiControllerBuilder(string serviceName)
    {
        if (string.IsNullOrWhiteSpace(serviceName))
        {
            throw new ArgumentException("serviceName null or empty!", "serviceName");
        }
 
        if (!DynamicApiServiceNameHelper.IsValidServiceName(serviceName))
        {
            throw new ArgumentException("serviceName is not properly formatted! It must contain a single-depth namespace at least! For example: 'myapplication/myservice'.", "serviceName");
        }
 
        _serviceName = serviceName;
 
        _actionBuilders = new Dictionary<string, ApiControllerActionBuilder<T>>();
        foreach (var methodInfo in DynamicApiControllerActionHelper.GetMethodsOfType(typeof(T)))
        {
            _actionBuilders[methodInfo.Name] = new ApiControllerActionBuilder<T>(this, methodInfo);
        }
    }
 
    /// <summary>
    /// The adds Action filters for the whole Dynamic Controller
    /// </summary>
    /// <param name="filters"> The filters. </param>
    /// <returns>The current Controller Builder </returns>
    public IApiControllerBuilder<T> WithFilters(params IFilter[] filters)
    {
        _filters = filters;
        return this;
    }
 
    /// <summary>
    /// Used to specify a method definition.
    /// </summary>
    /// <param name="methodName">Name of the method in proxied type</param>
    /// <returns>Action builder</returns>
    public IApiControllerActionBuilder<T> ForMethod(string methodName)
    {
        if (!_actionBuilders.ContainsKey(methodName))
        {
            throw new AbpException("There is no method with name " + methodName + " in type " + typeof(T).Name);
        }
 
        return _actionBuilders[methodName];
    }
 
    /// <summary>
    /// Builds the controller.
    /// This method must be called at last of the build operation.
    /// </summary>
    public void Build()
    {
        var controllerInfo = new DynamicApiControllerInfo(_serviceName, typeof(DynamicApiController<T>), _filters);
         
        foreach (var actionBuilder in _actionBuilders.Values)
        {
            if (actionBuilder.DontCreate)
            {
                continue;
            }
 
            controllerInfo.Actions[actionBuilder.ActionName] = actionBuilder.BuildActionInfo();
        }
 
        IocManager.Instance.IocContainer.Register(
            Component.For<AbpDynamicApiControllerInterceptor<T>>().LifestyleTransient(),
            Component.For<DynamicApiController<T>>().Proxy.AdditionalInterfaces(new[] { typeof(T) }).Interceptors<AbpDynamicApiControllerInterceptor<T>>().LifestyleTransient()
            );
 
        DynamicApiControllerManager.Register(controllerInfo);
 
        LogHelper.Logger.DebugFormat("Dynamic web api controller is created for type '{0}' with service name '{1}'.", typeof(T).FullName, controllerInfo.ServiceName);
    }
}