AppBuilder（一）Use汇总

internal static OwinAppContext Build()
        {
            Action<IAppBuilder> startup = GetAppStartup();
            return Build(startup);
        }

 1 internal static OwinAppContext Build(Action<IAppBuilder> startup)
 2         {
 3             if (startup == null)
 4             {
 5                 throw new ArgumentNullException("startup");
 6             }
 7 
 8             var appContext = new OwinAppContext();    //实例化OwinAppContext，主要获得网站名称和程序名称
 9             appContext.Initialize(startup);    //进一步初始化OwinAppContext
10             return appContext;
11         }

 1 internal void Initialize(Action<IAppBuilder> startup)
 2         {
 3             Capabilities = new ConcurrentDictionary<string, object>();    //初始化为多线程安全的Dictionary，说明为多线程共享资源
 4 
 5             var builder = new AppBuilder();    //初始化AppBuilder，向Properties中填入一些基本信息，这构成了Server环境的快照
 6             builder.Properties[Constants.OwinVersionKey] = Constants.OwinVersion;
 7             builder.Properties[Constants.HostTraceOutputKey] = TraceTextWriter.Instance;
 8             builder.Properties[Constants.HostAppNameKey] = AppName;
 9             builder.Properties[Constants.HostOnAppDisposingKey] = OwinApplication.ShutdownToken;
10             builder.Properties[Constants.HostReferencedAssemblies] = new ReferencedAssembliesWrapper();
11             builder.Properties[Constants.ServerCapabilitiesKey] = Capabilities;
12             builder.Properties[Constants.SecurityDataProtectionProvider] = new MachineKeyDataProtectionProvider().ToOwinFunction();
13             builder.SetLoggerFactory(new DiagnosticsLoggerFactory());
14 
15             Capabilities[Constants.SendFileVersionKey] = Constants.SendFileVersion;
16 
17             CompilationSection compilationSection = (CompilationSection)System.Configuration.ConfigurationManager.GetSection(@"system.web/compilation");
18             bool isDebugEnabled = compilationSection.Debug;
19             if (isDebugEnabled)
20             {
21                 builder.Properties[Constants.HostAppModeKey] = Constants.AppModeDevelopment;
22             }
23 
24             DetectWebSocketSupportStageOne();
25 
26             try
27             {
28                 startup(builder);    //真正的由用户定义的middleware注入开始了，这将完成pipeline的构造
29             }
30             catch (Exception ex)
31             {
32                 _trace.WriteError(Resources.Trace_EntryPointException, ex);
33                 throw;
34             }
35 
36             AppFunc = (AppFunc)builder.Build(typeof(AppFunc));//记录pipeline的第一个middleware，这将是整个pipeline的入口
37         }

 1 public AppBuilder()
 2         {
 3             _properties = new Dictionary<string, object>();    //初始化environment资源
 4             _conversions = new Dictionary<Tuple<Type, Type>, Delegate>();    //初始化转换器，这将不是本文重点，后期再涉及
 5             _middleware = new List<Tuple<Type, Delegate, object[]>>();    //初始化middleware列表
 6 
 7             _properties[Constants.BuilderAddConversion] = new Action<Delegate>(AddSignatureConversion);    //记录Conversion
 8             _properties[Constants.BuilderDefaultApp] = NotFound;
 9 
10             SignatureConversions.AddConversions(this);
11         }

 1 public partial class Startup
 2     {
 3         public void Configuration(IAppBuilder app)
 4         {
 5             ConfigureAuth(app);
 6         }
 7     }
 8 public partial class Startup
 9     {
10         public void ConfigureAuth(IAppBuilder app)
11         {
12 
13             app.CreatePerOwinContext<BlogContext>(BlogContext.Create);    //将数据库上下文注入envrionment中
14             app.CreatePerOwinContext<AppUserManager>(AppUserManager.Create);    //将AppUserManager注入environment中
15             app.CreatePerOwinContext<AppSigninManager>(AppSigninManager.Create);    //将AppSigninManager注入environment中
16 
17             app.UseCookieAuthentication(new CookieAuthenticationOptions    //标记CookeAuthentication这个middleware在pipeline中的stage，并配置参数
18             {
19                 AuthenticationType = DefaultAuthenticationTypes.ApplicationCookie,
20                 LoginPath = new PathString("/Account/Login"),
21                 Provider = new CookieAuthenticationProvider
22                 {
23                     // Enables the application to validate the security stamp when the user logs in.
24                     // This is a security feature which is used when you change a password or add an external login to your account. 
25                     OnValidateIdentity = SecurityStampValidator.OnValidateIdentity<AppUserManager, AppUser>(
26                         validateInterval: TimeSpan.FromMinutes(30),
27                         regenerateIdentity: (manager, user) => user.GenerateUserIdentityAsync(manager))
28                 }
29             });
30 
31             // Enables the application to remember the second login verification factor such as phone or email.
32             // Once you check this option, your second step of verification during the login process will be remembered on the device where you logged in from.
33             // This is similar to the RememberMe option when you log in.
34             app.UseTwoFactorRememberBrowserCookie(DefaultAuthenticationTypes.TwoFactorRememberBrowserCookie);    //标记stage
35         }
36 
37     }

 1 private static readonly IList<string> StageNames = new[]
 2         {
 3             Constants.StageAuthenticate,
 4             Constants.StagePostAuthenticate,
 5             Constants.StageAuthorize,
 6             Constants.StagePostAuthorize,
 7             Constants.StageResolveCache,
 8             Constants.StagePostResolveCache,
 9             Constants.StageMapHandler,
10             Constants.StagePostMapHandler,
11             Constants.StageAcquireState,
12             Constants.StagePostAcquireState,
13             Constants.StagePreHandlerExecute,
14         };

 1 public static class CookieAuthenticationExtensions
 2     {
 3         public static IAppBuilder UseCookieAuthentication(this IAppBuilder app, CookieAuthenticationOptions options)
 4         {
 5             return app.UseCookieAuthentication(options, PipelineStage.Authenticate);    //在PipelineStage.Authenticate阶段执行
 6         }
 7 
 8         public static IAppBuilder UseCookieAuthentication(this IAppBuilder app, CookieAuthenticationOptions options, PipelineStage stage)
 9         {
10             if (app == null)
11             {
12                 throw new ArgumentNullException("app");
13             }
14 
15             app.Use(typeof(CookieAuthenticationMiddleware), app, options);    //app.Use实际上就是将middleware压入middleware的List中
16             app.UseStageMarker(stage);    //标记middleware所在stage
17             return app;
18         }
19     }

  public IAppBuilder Use(object middleware, params object[] args)
        {
            _middleware.Add(ToMiddlewareFactory(middleware, args));
            return this;
        }

 1 private static Tuple<Type, Delegate, object[]> ToMiddlewareFactory(object middlewareObject, object[] args)    //接受两个参数，返回一个三元组
 2         {
 3             if (middlewareObject == null)
 4             {
 5                 throw new ArgumentNullException("middlewareObject");
 6             }
 7 
 8             var middlewareDelegate = middlewareObject as Delegate;    //尝试将middlewareObject类型转换为Delegate，而我们上面传入的是一个Type，将会转换失败
 9             if (middlewareDelegate != null)    //如果转换成功
10             {
11                 return Tuple.Create(GetParameterType(middlewareDelegate), middlewareDelegate, args);    //直接返回三元组，这似乎是最理想的情况
12             }
13 
14             Tuple<Type, Delegate, object[]> factory = ToInstanceMiddlewareFactory(middlewareObject, args);    //尝试在middlewareObject类中寻找Initialize方法，并检查args参
15     //数是否符合Initialize方法的参数
16             if (factory != null)
17             {
18                 return factory;
19             }
20 
21             factory = ToGeneratorMiddlewareFactory(middlewareObject, args);    //尝试在middlewareObject类中寻找Invoke方法，并作参数检查
22 
23             if (factory != null)
24             {
25                 return factory;
26             }
27 
28             if (middlewareObject is Type)    //这是本文的app.Use方法传入的参数类型，所以会进入这一流程中
29             {
30                 return ToConstructorMiddlewareFactory(middlewareObject, args, ref middlewareDelegate);
31             }
32 
33             throw new NotSupportedException(string.Format(CultureInfo.CurrentCulture,
34                 Resources.Exception_MiddlewareNotSupported, middlewareObject.GetType().FullName));
35 
36         }

 1 private static Tuple<Type, Delegate, object[]> ToInstanceMiddlewareFactory(object middlewareObject, object[] args)
 2         {
 3             MethodInfo[] methods = middlewareObject.GetType().GetMethods();    //将middleware当作一个实例处理，获取其Type，再获得类中所有方法
 4             foreach (var method in methods)    //遍历方法
 5             {
 6                 if (method.Name != Constants.Initialize)    //寻找Initialize方法
 7                 {
 8                     continue;
 9                 }
10                 ParameterInfo[] parameters = method.GetParameters();    //获取Initialize的参数表
11                 Type[] parameterTypes = parameters.Select(p => p.ParameterType).ToArray();    //获取参数表的Type类型
12 
13                 if (parameterTypes.Length != args.Length + 1)    //Initialize的参数应该比args的参数多一个，因为第一个参数应该是下一个middleware
14                 {
15                     continue;
16                 }
17                 if (!parameterTypes
18                     .Skip(1)
19                     .Zip(args, TestArgForParameter)
20                     .All(x => x))
21                 {    //对Initialize第一个以后的参数与args进行一对一验证，args应该为对应项的实例
22                     continue;
23                 }
24          
25                 // DynamicInvoke can‘t handle a middleware with multiple args, just push the args in via closure.
26                //开发者在此处注释动态Invoke无法处理middleware有多个参数的情况，所以进行了一次封装，简化参数表
27                 Func<object, object> func = app =>
28                 {
29                     object[] invokeParameters = new[] { app }.Concat(args).ToArray();    //将app（实际上为envrionment）参数与args合并
30                     method.Invoke(middlewareObject, invokeParameters);    //真正调用middleware的Initialize方法
31                     return middlewareObject;    //返回middlewareObject实例
32                 };
33 
34                 return Tuple.Create<Type, Delegate, object[]>(parameters[0].ParameterType, func, new object[0]);
35             }
36             return null;
37         }

 1 private static Tuple<Type, Delegate, object[]> ToGeneratorMiddlewareFactory(object middlewareObject, object[] args)
 2         {
 3             MethodInfo[] methods = middlewareObject.GetType().GetMethods();    //将middlewareObject当作一个实例，获取Type并获取所有方法
 4             foreach (var method in methods)
 5             {
 6                 if (method.Name != Constants.Invoke)    //寻找Invoke方法
 7                 {
 8                     continue;
 9                 }
10                 ParameterInfo[] parameters = method.GetParameters();    //获取Invoke方法的参数表
11                 Type[] parameterTypes = parameters.Select(p => p.ParameterType).ToArray();    //获取参数的Type表
12 
13                 if (parameterTypes.Length != args.Length + 1)
14                 {
15                     continue;
16                 }
17                 if (!parameterTypes
18                     .Skip(1)
19                     .Zip(args, TestArgForParameter)
20                     .All(x => x))
21                 {    //将Type表与args进行一对一验证
22                     continue;
23                 }
24                 IEnumerable<Type> genericFuncTypes = parameterTypes.Concat(new[] { method.ReturnType });    //将参数Type表与返回Type合并
25                 Type funcType = Expression.GetFuncType(genericFuncTypes.ToArray());    //获取方法签名Type
26                 Delegate middlewareDelegate = Delegate.CreateDelegate(funcType, middlewareObject, method);    //对实例的Invoke方法进行delegate封装
27                 return Tuple.Create(parameters[0].ParameterType, middlewareDelegate, args);
28             }
29             return null;
30         }

 1 private static Tuple<Type, Delegate, object[]> ToConstructorMiddlewareFactory(object middlewareObject, object[] args, ref Delegate middlewareDelegate)
 2         {
 3             var middlewareType = middlewareObject as Type;    //尝试将middlwareObject转换为Type
 4             ConstructorInfo[] constructors = middlewareType.GetConstructors();    //获取类的构造方法
 5             foreach (var constructor in constructors)    //遍历构造方法
 6             {
 7                 ParameterInfo[] parameters = constructor.GetParameters();    //获取构造函数的参数表
 8                 Type[] parameterTypes = parameters.Select(p => p.ParameterType).ToArray();    //获取参数的Type表
 9                 if (parameterTypes.Length != args.Length + 1)    //参数表应该比args多一项，第一项应该为下一个middleware
10                 {
11                     continue;
12                 }
13                 if (!parameterTypes
14                     .Skip(1)
15                     .Zip(args, TestArgForParameter)
16                     .All(x => x))
17                 {    //对参数表的第一项之后的与args一对一校验
18                     continue;
19                 }
20 
21                 ParameterExpression[] parameterExpressions = parameters.Select(p => Expression.Parameter(p.ParameterType, p.Name)).ToArray();    //提取参数表的Type和Name
22                 NewExpression callConstructor = Expression.New(constructor, parameterExpressions);    //创建构造函数
23                 middlewareDelegate = Expression.Lambda(callConstructor, parameterExpressions).Compile();    //对构造函数进行Lambda封装
24                 return Tuple.Create(parameters[0].ParameterType, middlewareDelegate, args);
25             }
26 
27             throw new MissingMethodException(string.Format(CultureInfo.CurrentCulture,
28                 Resources.Exception_NoConstructorFound, middlewareType.FullName, args.Length + 1));
29         }

 1 public static IAppBuilder Use<T>(this IAppBuilder app, params object[] args)
 2         {
 3             if (app == null)
 4             {
 5                 throw new ArgumentNullException("app");
 6             }
 7 
 8             return app.Use(typeof(T), args);
 9 
10         }

 1 public static IAppBuilder Use(this IAppBuilder app, Func<IOwinContext, Func<Task> /*next*/, Task> handler)
 2         {
 3             if (app == null)
 4             {
 5                 throw new ArgumentNullException("app");
 6             }
 7             if (handler == null)
 8             {
 9                 throw new ArgumentNullException("handler");
10             }
11 
12             return app.Use<UseHandlerMiddleware>(handler);
13         }

 1 public static void Run(this IAppBuilder app, Func<IOwinContext, Task> handler)
 2         {
 3             if (app == null)
 4             {
 5                 throw new ArgumentNullException("app");
 6             }
 7             if (handler == null)
 8             {
 9                 throw new ArgumentNullException("handler");
10             }
11 
12             app.Use<UseHandlerMiddleware>(handler);
13         }

 1 //这是对UseExtensionOne的实际应用
 2             app.Use((context, next) =>
 3             {
 4                 PrintCurrentIntegratedPipelineStage(context, "Middleware 1");
 5                 return next.Invoke();
 6             });
 7             //这是对UseExtensionOne的实际应用
 8             app.Use((context, next) =>
 9             {
10                 PrintCurrentIntegratedPipelineStage(context, "2nd MW");
11                 return next.Invoke();
12             }); 
13             //这是对RunExtentionTwo的实际应用
14             app.Run(context =>
15             {
16                 PrintCurrentIntegratedPipelineStage(context, "3rd MW");
17                 return context.Response.WriteAsync("Hello world");
18             });