MVC Api 的跨项目路由

现有Momoda.Api项目，由于团队所有人在此项目下开发，导致耦合度太高，现从此接口项目中拆分出多个子项目从而避免对Momda.Api的改动导致“爆炸”

MVCApi的跨项目路由和MVC有解决方式有点不同

第一步：

首先在Momoda下创建域创建好之后把生成的YZCAreaRegistration文件移动到Areas目录下YZC目录外，然后排除YZC文件夹，像这样：

第二步：

创建一个新的MVCApi叫 YZC.WebAi,在资源管理器中用 YZC.WebAi文件夹下的内容替换掉Areas下的YZC域文件夹中的内容，并且只留下Controllers,Views和Models三个文件夹，其他的config和Global等都删除

第三步：

右键LYL解决方案添加现有项目在YZC域下找到工程文件 （ LYLMomoda.ApiAreas）

这样就把Momoda.Api下的YZC域给拆分出来，开发过程中只关注YZC.WebApi即可，目录结构如下图：

第四步：

更改YZCAreaRegistration域路由文件。

Api路由文件的更改是否和MVC跨域路由一样添加context.MapRoute方法的最后一个命名空间参数就能解决呢？答案当然没有那么简单。。。。。哈哈哈哈

我们现验证以下是否按照MVC跨项目路由的解决方案也同样适用于Api。

更改父API项目的域路由文件：

public override void RegisterArea(AreaRegistrationContext context)
        {
            context.MapRoute(
                "YZC_default",
                "YZC/{controller}/{action}/{id}",
                new { action = "Index", id = UrlParameter.Optional },
                new string[] { "YZC.Controllers" }//添加域项目的控制层命名空间
            );
        }

在子api项目中添加controller：

{
    public class ChildrenController : ApiController
    {  
#region 跨项目路由测试
        [HttpGet]
        public string Test()
        {
            return "小良哥";
        }
        #endregion
    }
}

浏览器中测试结果：

没有路由到，表明MVC域的处理和Api域的处理是不同的

解决方案：

在父ApiMomoda.Api下的App_Start中新增叫CustomHttpControllerSelector的类并且继承DefaultHttpControllerSelector

代码如下：

/// <summary>
    /// 自定义区域类
    /// </summary>
    public class CustomHttpControllerSelector: DefaultHttpControllerSelector
    {
        private const string NamespaceRouteVariableName = namespaceName";
//namespaceName之后要用到
        //private const string AreaRouteVariableName = "area";
        private readonly HttpConfiguration _configuration;
        private readonly Lazy<ConcurrentDictionary<string, Type>> _apiControllerCache;

        public CustomHttpControllerSelector(HttpConfiguration configuration)
            : base(configuration)
        {
            _configuration = configuration;

            _apiControllerCache = new Lazy<ConcurrentDictionary<string, Type>>(
                new Func<ConcurrentDictionary<string, Type>>(InitializeApiControllerCache));
        }


        private ConcurrentDictionary<string, Type> InitializeApiControllerCache()
        {
            IAssembliesResolver assembliesResolver = this._configuration.Services.GetAssembliesResolver();
            var types = this._configuration.Services.GetHttpControllerTypeResolver()
                .GetControllerTypes(assembliesResolver).ToDictionary(t => t.FullName, t => t);

            return new ConcurrentDictionary<string, Type>(types);
        }

        public IEnumerable<string> GetControllerFullName(HttpRequestMessage request, string controllerName)
        {
            object namespaceName;
            var data = request.GetRouteData();
            IEnumerable<string> keys = _apiControllerCache.Value.ToDictionary<KeyValuePair<string, Type>, string, Type>(t => t.Key,
                    t => t.Value, StringComparer.OrdinalIgnoreCase).Keys.ToList();

            if (!data.Values.TryGetValue(NamespaceRouteVariableName, out namespaceName))
            {
                return from k in keys
                       where k.EndsWith(string.Format(".{0}{1}", controllerName,
                       DefaultHttpControllerSelector.ControllerSuffix), StringComparison.OrdinalIgnoreCase)
                       select k;
            }

            string[] namespaces = (string[])namespaceName;
            return from n in namespaces
                   join k in keys on string.Format("{0}.{1}{2}", n, controllerName,
                   DefaultHttpControllerSelector.ControllerSuffix).ToLower() equals k.ToLower()
                   select k;
        }


        public override HttpControllerDescriptor SelectController(HttpRequestMessage request)
        {
            Type type;
            if (request == null)
            {
                throw new ArgumentNullException("request");
            }

            string controllerName = this.GetControllerName(request);
            if (string.IsNullOrEmpty(controllerName))
            {
                throw new HttpResponseException(request.CreateErrorResponse(HttpStatusCode.NotFound,
                    string.Format("No route providing a controller name was found to match request URI '{0}'",
                    new object[] { request.RequestUri })));
            }

            IEnumerable<string> fullNames = GetControllerFullName(request, controllerName);
            if (fullNames.Count() == 0)
            {
                throw new HttpResponseException(request.CreateErrorResponse(HttpStatusCode.NotFound,
                        string.Format("No route providing a controller name was found to match request URI '{0}'",
                        new object[] { request.RequestUri })));
            }

            if (!this._apiControllerCache.Value.TryGetValue(fullNames.First(), out type))
            {
                throw new HttpResponseException(request.CreateErrorResponse(HttpStatusCode.NotFound,
                        string.Format("No route providing a controller name was found to match request URI '{0}'",
                        new object[] { request.RequestUri })));
            }

            return new HttpControllerDescriptor(_configuration, controllerName, type);
        }
    }

更改父API项目的域路由文件为：

namespace Momoda.Api
{
    public class YZCAreaRegistration : AreaRegistration
    {
        public override string AreaName//域名称
        {
            get
            {
                return "YZC";
            }
        }
        public override void RegisterArea(AreaRegistrationContext context)
        {
            context.Routes.MapHttpRoute(
                  name: this.AreaName + "_default",
                  routeTemplate: "api/" + this.AreaName + "/{controller}/{action}/{id}",
                  defaults: new
           {
          id = RouteParameter.Optional,
          namespaceName = new string[] { string.Format("{0}.Controllers",this.AreaName) }
 //namespaceName名称要CustomHttpControllerSelector中NamespaceRouteVariableName的值一致
          }
              );  
        }
    }
}

这样就完成了吗？没有！！！必须把域YZC.WebApi生成路径设置为Momoda.Api的bin文件下

测试结果：

成功！

域名称可加可不加同样成功

17:57:11，嘿嘿，下班啦