Java Building Web Apps with Spring Rob Harrop, Interface21 Ltd.

Transcription

1 Java Building Web Apps with Spring Rob Harrop, Interface21 Ltd.

2 Contact me at About the Speaker VP at Interface21 Core Developer on Spring Founder of Spring Modules JMX 2.0 Expert Group Member Author of Pro Spring

3 Agenda Tools for Web Development Getting Started Basic User Interactions Handling Site Formatting User Conversations with Web Flow Adding Security Handling Exceptions Interception and Filtering

4 Tools for Web Development Get a good IDE: IntelliJ IDEA Eclipse with WTP NetBeans Consider using Jetty for development Rapid turn around Easy to edit view files, flow definitions etc Maven is a good tool for managing Jetty

5 Tools for Web Development Spring and Spring Web Flow Site Formatting SiteMesh Tiles CSS Framework ContentWithStyle.co.uk

6 Getting Started 1.Create basic web application skeleton 1.Consider Maven as a kick start 2.Configure Spring's DispatcherServlet 3.Create a Spring Web Application config file 4.Configure ContextLoaderListener and middle tier configuration files as needed

7 DEMO: Basic Web Application Configuration

8 Basic User Interactions Logic encapsulated in Controllers Implement Controller directly Extend AbstractController, MultiActionController or SimpleFormController

9 Basic User Interactions Controllers return a ModelAndView which describes: The view to render Data for that view

10 View Resolution Typically views are represented as String names Decoupled from the actual view implementation Easy to test

11 View Resolution These names are mapped to concrete views using a ViewResolver: InternalResourceViewResolver BeanNameViewResolver VelocityViewResolver Many applications have multiple ViewResolvers configured in a chain

12 Mapping Controllers to URIs Controllers are configured as beans in the web application config file Can have injected dependencies Declarative services

13 Mapping Controllers to URIs These Controller beans are mapped to URIs using a HandlerMapping: SimpleUrlHandlerMapping BeanNameHandlerMapping HandlerMappings are also configured in the web application config file

14 DEMO: Creating and Configuring a Controller

15 Site-Wide Formatting Most web applications require consistent formatting across the site Headers Navigation Footers Ads Adding this by hand can be painful and error-prone

16 Handling Site-Wide Formatting Site-wide formatting can be applied automatically Do not cut and paste across pages! Use a pre-built tool SiteMesh and Tiles are good candidates Couple this with a strong CSS-based layout I use a pre-built CSS framework from ContentWithStyle

17 Site-Wide Formatting with SiteMesh 1. Configure the SiteMesh filter 2. Create a decorators.xml file 1. Define your page decorators 3. Create your decorator(s)

18 DEMO: SiteMesh in Action

19 User Conversations with Web Flow Web Flow provides a sophisticated mechanism for controlling long running user interactions Conversations are mapped as fa low using standard state machines concepts

20 User Conversations with Web Flow Web Flow is integrated with Spring MVC View resolution works the same way Exception resolution works the same way

21 Web Flow Concepts State A single stage in the execution of a flow Action A piece of logic that can be executed a various points during the flow

22 Web Flow Concepts Event A user or action initiated event such as submit or process Transition A movement from one state to another in response to some event

23 Web Flow Concepts View State A state that constitutes a pause in the flow execution and renders a view for the user Action State A state type that executes one or more Actions before proceeding to another State

24 Web Flow Concepts Flow Executor Manages flow execution. Resumes and pauses flows as they proceed Flow Repository Store in-progress flow execution state Simple and continuation-based implementations provided

25 Flow Registry Web Flow Concepts Registry of flow definitions

26 Getting Started with Web Flow 1.Configure Flow Registry 2.Configure Flow Executor 3.Optionally configure Flow Repository 4.Create Flow Definition 5.Configure a FlowController for your flow

27 Configuring Web Flow Configure the FlowExecutor and FlowRegistry <flow:executor id="flowexecutor" registry-ref="flowregistry"/> <flow:registry id="flowregistry"> <flow:location path="/web-inf/flows/**.xml"/> </flow:registry> Flows are XML files stored in /WEB-INF/flows

28 Configuring a FlowController <bean name="/checkout.html" class="o.s.w.ex.mvc.flowcontroller"> <property name="flowexecutor" ref="flowexecutor"/> <property name="defaultflowid" value="checkout"/> </bean>

29 DEMO: Order Process with Spring Web Flow

30 Handling Exceptions Exceptions that cannot be handled should be allowed to propagate These can be handled by some last-ditch process Servlet error pages Spring HandlerExceptionResolvers

31 Handling Exceptions HandlerExceptionResolver allows for: Last ditch processing Same contract as a Controller Access to thrown Exception Auto detected from the ApplicationContext

32 Handling Exceptions Spring provides SimpleMappingExceptionResolver Configurable mapping of Exception type to error view name

33 DEMO: Configuring a HandlerExceptionResolver

34 Interception and Filtering Spring web applications have three options for interception: Servlet Filters Spring HandlerInterceptors AOP

35 Interception and Filtering All three options can be treated as normal Spring beans: Dependency Injection Remote/JMX exposure

36 Uses for Interception and Filtering Conditional request processing Maintenance mode Redirect based on user type Tracing and profiling Thread local management

37 DEMO: Filtering and Interception in Action

38 Further Information Blog - SiteMesh - h ContentWithStyle -

39 Q&A