1	Modulo II Spring-MVC Prof. Ismael H F Santos
2	Bibliografia Spring in Action Craig Walls and Ryan Breidenbach Professional Java Development with Spring Rod Johnson, Juergen Hoeller and Team
3	Ementa Spring in the Web Tier Spring in the Middle Tier Spring-MVC
4	WebApp
5	Histórico Programação Web
6	Histórico Programação Web
7	Container Web – Java Container = gerenciador de objetos com ciclo de vida específico; Tem parte das funcionalidades de um Servidor de Aplicações J2EE; Ex.: Tomcat, Jetty, Resin, WebLogic, Oracle AS, WebSphere, JBoss, etc. JSR 53 = Servlet 2.3 e JSP 1.2; JSR 152 = JSP 2.0; JSR 154 = Servlet 2.4; JSR 245 = JSP 2.1; JSR 315 = Servlet 3.0; Os containers implementam as especificações.
8	Servlet Container
9	Java Server Pages
10	Servlet Controller
11	“Separation of concerns”
12	Model-View-Controller (MVC) Design Pattern MVC Clearly separates business, navigation and presentation logic. It´s a proven mechanism for building a thin, clean web-tier Model The domain-specific representation of the information on which the application operates. View Renders the model into a form suitable for interaction, typically a user interface element. Controller Processes and responds to events, typically user actions, and may invoke changes on the model.
13	Model-View-Controller (MVC) Design Pattern O que é o MVC padrão projeto para o desenvolvimento de aplicações, A implementação de aplicações usando este padrão são feitas com recurso a frameworks, apesar de não ser obrigatória a utilização de uma para seguir o padrão. Objetivo do MVC Isolar mudanças na GUI, evitando que estas mudanças acarretem em mudanças na Camada de Negicos da Aplcação (Application’s Domain Logic) Vantagens Facilita a manutenção Changes to business logic are less likely to break the presentation logic & vice-versa Facilita o desenvolvimento por times multi-disciplinares: desenvolvedores – creating robust business code designers – building usable and engaging UIs
14	Model-View-Controller (MVC) Design Pattern Camadas e respectivas funções Model: Define as regras de acesso e manipulação dos dados Armazenados em bases de dados ou ficheiros, mas nada indica que sirva só para alojamento persistente dos dados. Pode ser usado para dados em memória volátil, p.e.: memória RAM, apesar não se verificar tal utilização com muita frequência. Todas as regras relacionadas com tratamento, obtenção e validação dos dados devem ser implementados nesta camada. View: Responsável por gerar a forma como a resposta será apresentada, página web, formulário, relatório, etc... Controller: Responsável por responder aos pedidos por parte do utilizador. Sempre que um utilizador faz um pedido ao servidor esta camada é a primeira a ser executada.
15	Front Controller (Servlet Controller)
16	Especificações do J2EE - Arquiteturas de aplicação Web Model 1 Recomendado para projetos pequenos. E/S: Java Server Pages Lógica de negócio: Java Beans e EJBs Model 2 Recomendada para projetos médios e grandes. Variação do padrão MVC Controller: Servlets Model: JavaBeans e EJBs View: Java Server Pages
17	Futuro: WebBeans – JBoss Seam JSR 299 – Web Beans; Unificação dos modelos EJB 3 e JSF 2; EJB 3 traz idéias bem-sucedidas: ORM, DI, etc., porém a integração com JSF ainda é trabalhosa e tediosa. Web Beans unifica os modelos de componentes; JBoss Seam. O criador do Seam é Spec Lead do Web Beans. Integração JSF – EJB3 (modelo de componentes unificado); AJAX e jBPM integrados; Gerenciamento de estado declarativo; Bijection, Conversation e Workspaces; Utilização de POJOs com anotações; Testabilidade; I18n, autenticação, depuração, URLs RESTful, seam-gen, eventos, interceptadores, etc.
18	WebApp
19	Spring MVC Construído sobre o núcleo do Spring. Acomoda várias tecnologias de view: JSP, Velocity, Tiles, iText, POI etc. JSP, Velocity, Tiles, iText, POI etc. Pode ser combinado a outras web tiers: Struts, WebWork, Tapestry etc. Struts, WebWork, Tapestry etc. Configurável via strategy interfaces.
20	Proposed Web App Layering
21	Alguns Frameworks MVC Struts (Apache) Frameworks e toolkits para aplicações web. Voltado para o desenvolvimento de Model+Controller. Público-alvo: desenvolvedores - http://struts.apache.org/ Velocity (Apache) Template engine para referenciar objetos Java. Voltado para o desenvolvimento da View. Público-alvo: web designers http://jakarta.apache.org/velocity/ Java Server Faces (Sun) Tecnologia para construção de UIs web para aplicações Java. Voltado para o desenvolvimento da View. Público-alvo: desenvolvedores http://java.sun.com/javaee/javaserverfaces/
22	Where Spring Framework Fits Into a JEE Architecture
23	Web App – Scenario 1
24	Web App – Scenario 2
25	Web App – Scenario 3
26	Web App – Scenario 4
27	Spring on the Web Tier – Spring MVC Spring integrates nicely with Struts, WebWork, JSF, Tapestry, Velocity and other web frameworks Spring MVC, Spring’s own web framework. The Spring MVC Framework offers a simple interface based infrastructure for handing web MVC architectures Spring MVC components are treated as first-class Spring beans Other Spring beans can easily be injected into Spring MVC components Spring MVC components are easy to test
28	Spring MVC – Key Interfaces Controller (org.springframework.web.servlet.mvc.Controller) User created component for handling requests Encapsulates navigation logic Delegates to the service objects for business logic Must implement ModelAndView handleRequest(request, response) This is the base controller interface, comparable to the notion of a Struts Action.
29	Spring MVC – Key Interfaces View (org.springframework.web.servlet.mvc.View) Responsible for rendering output Must implement void render(model, request, response) This is the MVC view for a web interaction. Implementations are responsible for rendering content, and exposing the model. Model To complete the MVC trio, note that the model is typically handled as a java.util.Map which is returned with the view the values of the model are available, for example in a JSP, using a <jsp:useBean/> where the id corresponds to the key value in the Map
30	Spring MVC – Key Interfaces ModelAndView Created by the Controller Stores the Model data Associates a View to the request Can be a physical View implementation or a logical View name ViewResolver Used to map logical View names to actual View implementations HandlerMapping Strategy interface used by DispatcherServlet for mapping incoming requests to individual Controllers
31	MVC and Dependency Injection All MVC components are configured in the Spring ApplicationContext As such, all MVC components can be configured using Dependency Injection Example: <bean id="springCheersController" class="com....web.SpringCheersController"> <property name="methodNameResolver“ ref=“springCheersMethodResolver"/> <property name="service" ref="service"/> </bean>
32	Spring on the Web Tier: Integration with Other Frameworks Spring integrates nicely with other web frameworks with two methodologies: Look up Spring beans within Controllers/Actions via the convenience static method: WebApplicationContextUtils. getWebApplicationContext(servletContext).getBean(“beanName”) Configure the Controllers/Actions for the web framework in a Spring BeanFactory and then use Spring provided proxies in the actual web framework configuration When available, this methodology is preferred This approach lets you design your Controllers/Actions with dependency injection and makes your Controller/Actions more testable
33	WebApp
34	Aplicação Básica Web.xml Entry Standard J2EE web container servlet definition Establishes which and where listeners act on requests Bean Definitions ${servlet-name}-servlet.xml Beans unique to the the web context [created for the configured Servlet dispatcher] ApplicationContext.xml Beans common to all contexts
35	Aplicação Básica - Web.xml ${webapp}\WEB-INF\web.xml
36	Aplicação Básica - Web.xml ${webapp}\WEB-INF\web.xml
37	Aplicação Básica - Context Hierarchy
38	Spring-MVC - Controllers
39	Spring-MVC - DispatcherServlet
40	Spring MVC – Execução (Run-time)
41	Spring MVC Flow DispatcherServlet recebe requisições domeio externo (do navegador, por exemplo) e comanda o fluxo de tarefas no Spring MVC; HandlerMapping dada uma requisição em URL, este componente irá retornar o Controller que está associado a ela; Controller realiza comuniação entre o MVC do Spring com a camada de negócio. Retorna um objeto ModelAndView; ModelAndView armazena os dadosretornados pela camada de negócio para serem exibidos. Além disso, contêm um nome lógico de uma determinada View
42	Spring MVC Flow View contêm informações de renderização para que o usuário possa ver o que solicitou; ViewResolver a partir do nome lógico contido no objeto ModelAndView, este componente determina a View que será exibida. DispatcherServlet Delega operações para outros componentes; web.xml -->
43	Spring MVC Flow – Pre Dispatcher
44	Spring MVC Flow – Pre Dispatcher
45	Spring MVC Flow – Dispatcher
46	Spring MVC Flow – Dispatcher
47	Handler Mappings The process of Handler Mapping binds incoming web requests to appropriate handlers that then resolve to a Controller(s) (in most cases) On inbound requests, the DispatcherServlet hands it over to the handler mapping to come up with an appropriate HandlerExecutionChain Note: Handler Mappings apply from the base url-pattern specified in the web.xml By default, if no handler mapping can be found in the context, the DispatcherServlet creates a BeanNameUrlHandlerMapping for you
48	“Out of the box” HandlerMappings Concrete Implementations BeanNameUrlHandlerMapping maps incoming HTTP requests to names of beans, defined in the web application context SimpleUrlHandlerMapping Map Ant-style path matching (see org.springframework.util.PathMatcher) to a Controller CommonsPathMapHandlerMapping use Commons Attributes to determine mapping ControllerClassNameHandlerMapping Most often, the out-of-the box implementations are sufficient
49	“Out of the box” HandlerMappings BeanNameUrlHandlerMapping; procura por controladores cujo nome corresponde à alguma porção de um nome URL de alguma requisição. SimpleUrlHandlerMapping; é que é muito mais versátil, pois ele permite que se declare uma lista de associações url-controladores, e não interfere na nomencaltura dos beans de controladores, deixando-os mais claros.
50	Anecdote: Under the covers Mapping Execution
51	Anecdote: Under the covers Mapping Execution
52	Spring-MVC As you can see, all incoming HTTP requests from a web browser are handled by Controllers. A controller, as the name indicates, controls the view and model by facilitating data exchange between them. The key benefit of this approach is that the model can worry only about the data and has no knowledge of the view. The view, on the other hand, has no knowledge of the model and business logic and simply renders the data passed to it (as a web page, in our case) The MVC pattern also allows us to change the view without having to change the model
53	Spring-MVC The DispatcherServlet is an actual Servlet Requests that you want the DispatcherServlet to handle will have to be mapped using a URL mapping in the same web.xml file.
54	Spring-MVC Each DispatcherServlet has its own WebApplicationContext, which inherits all the beans already defined in the root WebApplicationContext. file named [servlet-name]-servlet.xml in the WEB-INF directory
55	Spring-MVC With the above servlet configuration in place, you will need to have a file called '/WEB-INF/golfing-servlet.xml' in your application; this file will contain all of your Spring Web MVC-specific components (beans). The exact location of this configuration file can be changed via a servlet initialization parameter (see below for details).
56	Spring-MVC Controllers Spring provides many types of controllers. The controller type depends on the functionality you need. For example, do your screens contain a form? Do you need wizardlike functionality? Do you just want to redirect to a JSP page and have no controller at all?
57	Spring-MVC Objects Model & View Many of the methods in the Controller related subclasses return a org.springframework.web.servlet.ModelAndView object.This object holds the model (as a java.util.Map object) and view name and makes it possible to return both in one return value from a method. Command (Form Backing) Object Spring uses the notion of a command object, which is a JavaBean class that gets populated with the data from an HTML form’s fields. This same object is also passed to our validators for data validation, and if the validations pass, it is passed to the onSubmit method (in controller related classes) for processing of valid data.
58	Spring-MVC Validator An optional class that can be invoked for validating form data for a given command (form) controller. This validator class is a concrete class that implements org.springframework.validation.Validator interface. One of the two methods required by this interface is the validate method, which is passed a command object, as mentioned previously, and an Errors object, which is used to return errors. Another notable validation class is org.springframework.validation. ValidationUtils, which provides methods for rejecting empty fields. Spring Tag Library (spring-form.tld in spring.jar) The spring bind tag library is simple yet powerful. It is typically used in JSP files via the <spring:bind> tag, which essentially binds HTML form fields to the command object.
59	Spring-MVC Configuration Concepts DispatcherServlet DispatcherServlet (part of the org.springframework.web.servlet package) is the entry point to the world of Spring Web MVC. Handler Mappings You can map handlers for incoming HTTP requests in the Spring application context file.These handlers are typically controllers that are mapped to partial or complete URLs of incoming requests The handler mappings can also contain optional interceptors, which are invoked before and after the handler.
60	Spring-MVC View Resolvers Resolve view names to the actual views (enterhours to enterhours.jsp, for example). InternalResourceViewResolver is a class to resolve view names. Installing the Spring Framework on a Servlet Container Spring Framework can be downloaded from http://springframework.org.
61	Use of Interceptors Some HandlerMappings allow you to call an interceptor before the controller Useful for checking for session timeout, adding things to the request/session common services: security, traffic logging, and perhaps front-end common data validation Implement the HandlerInterceptor Interface Simply wire your implemented Interceptors into the HandlerMapping Kind of like AOP, but for Controllers
62	Use of Interceptors
63	WebApp
64	Spring MVC Flow: Controller
65	MVC: Give me a “C”
66	The Simple Controller Interface
67	Spring-MVC Controllers SimpleFormController, UrlFilenameViewController and AbstractController are the most often used.
68	Spring-MVC Controllers AbstractController basic, knows about caching, turning on/off get/set/post/head ParameterizableViewController always go to the same view UrlFileNameViewController parses the URL to return a view (http://blah/foo.html -> foo) SimpleFormController for form handling, hooks for attaching commands, validator AbstractWizardFormController easy wizard controller ServletWrappingController delegates to a servlet
69	“Out of the box” Controllers Infrastructure AbstractController Command Controllers AbstractCommandController BaseCommandController Form SimpleFormController AbstractFormController AbstractWizardFormController CancellableFormController Specialized MultiActionController ServletWrappingController Resource ParameterizableViewController ServletForwardingController AbstractUrlViewController UrlFilenameViewController
70	Spring-MVC Controllers
71	Annotation-driven Controllers
72	Example of Annotated MVC Controller
73	Creating a Basic Controller
74	Handling Forms Set the Command (just a bean) Set a Validator if needed (extend org.springframework.validation.Validator) Set destination views (form, success, failure, error) By default, uses GET/POST to determine whether it needs to load the form or process it
75	WebApp
76	Spring MVC Flow: View Resolving
77	View Resolving If the ModelAndView suppplied to the Dispatcher from a Controller requires resolution (the isReference() method is true), the a ViewResolver has the responsibility for finding a view matching the configured names View names are mapped to actual view implementations using ViewResolvers ViewResolvers are configured in the web-tier ApplicationContext Automatically detected by DispatcherServlet Can configure multiple, ordered ViewResolver
78	View Resolver O ViewResolver obtém o View a ser usado pelo aplicativo através da referência passada pelo objeto ModelAndView, que por sua vez foi retornado por algum Controller; Tipos de ViewResolver InternalResourceViewResolver; BeanNameViewResolver; ResourceBundleViewResolver; XmlViewResolver;
79	View Resolving: Implementation Classes
80	Different Views Plenty of Views are packaged with Spring MVC: JstlView map to a JSP page RedirectView Perform an HTTP Redirect TilesView, TilesJstlView integration with tiles VelocityLayoutView, VelocityToolboxView, VelocityView Integration with the Velocity templating tool FreeMarkerView use the FreeMarker templating tool JasperReportsView, JasperReportsMultiFormatView, JasperReportsMultiFormatView, JasperReportsPdfView, JasperReportsXlsView Support for Jasper Reports
81	Creating a View with JSP and JSTL
82	WebApp
83	Configuring DispatcherServlet
84	Configuring ContextLoaderListener
85	Mapping URLs to Controllers
86	Configure a HandlerMapping
87	Configuring the ViewResolver
88	Spring MVC Flow: View Routing
89	Anecdote: View Routing Search Order
90	Anecdote: View Routing Search Order From Spring 2 Reference Document 13.5.2: “Chaining ViewResolvers: the contract of a view resolver mentions that a view resolver can return null to indicate the view could not be found. Not all view resolvers do this however! … Check the Javadoc for the view resolver to see if you're dealing with a view resolver that does not report non-existing views.”
91	Spring MVC Flow: View
92	Spring MVC Flow: View
93	Spring MVC Flow: View
94	Spring MVC Run-time Flow
95	JSTL Introduction: What is it? What is JSTL? JavaServer Pages Standard Tag Library, JSR 52. JSTL provides an effective way to embed logic within a JSP page without using embedded Java code directly. Goal Provide the tags to the web page authors, so that they can easily access and manipulate the application data without using the scriptlets (java code).
96	JSTL Introduction: What is it? Other facts JSP tags are xml like tags, which can be used by non-programmers (page authors or designers) without knowledge of Java programming. Because JSTL tags are xml, they fit nicely into an XHTML strategy allowing web pages have greater tool vender support (for validation and dynamic data insertion) among other beneficial attributes (such as schema support). Bean driven (for data setting/access)
97	JSTL Introduction: Concepts Tag Library Xml compliant structures performing JSP features without knowledge of Java programming. Concepts such as flow control (if, for each) and more… Tags are extendable Expression Language Allows former java Scriptlet logic to be simplified into expressions Expression functions are extendable
98	JSTL Introduction: Before / After old
99	JSTL Introduction: EL Expressions
100	JSTL Introduction: Other Resources http://www.sitepoint.com/print/java-standard-tag-library http://java.sun.com/j2ee/1.4/docs/tutorial/doc/JSTL4.html http://en.wikipedia.org/wiki/JSTL http://www.roseindia.net/jstl/jstl.shtml … lots more! (one word: Google)
101	Spring TagLib: Using JSTL
102	“Templating” using Spring & JSTL
103	Model to HTML Binding
104	String Externalization in JSTL I18N functionality in JSTL is provided by the “fmt” tag Locale and resource bundles Formatting for numbers, dates, and currency
105	String Externalization in JSTL Spring enhances these I18N support tags with it’s own <Spring:message> tag MessageSource integrated with Spring context Define where your messages are stored Works with the locale support that comes with Spring Spring gives more flexibility in how the locale for messages is resolved… fmt:message tag uses request.getLocale() to establish the locale for messages
106	Form to Object Binding
107	Spring TagLib Starting in Spring 2, a standard JSTL Tag Library was added to help simplify form-based web pages form input checkbox radiobox password select
108	Spring TagLib: Binding Forms
109	Form Error Handling Built-in workflow for form error management Servers side Validator(s) Identifiers errors at a “field” level Leverages Message keys for Locale support JSTL tags <spring:hasBindErrors name=“commandObjName"> <form:errors path=“myBeanFieldName" />
110	Form Error Handling
111	Themes and Localization Themes a collection of static resources affecting the visual style of the application, typically style sheets and images. Localization DispatcherServlet enables you to automatically resolve messages using the client's locale via the LocaleResolver
112	Theme and Locale: Resolver and Intercepter
113	Theme Management Configuration
114	"FIM" FIM
115	Java Server Faces JSR 127 – padrão oficial (27/05/2004); Várias implementações; Garantia de continuidade. Similar aos frameworks MVC; Foco no desenvolvedor: Projetado para ser utilizado por IDEs; Componentes UI extensíveis; Tratamento de eventos (como no Swing!); Suporte à navegação simples.
116	Ciclo de Vida de uma aplicação JSF