Sample Chapter 13 - Manning Publications

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This chapter covers ■ Mapping requests to Spring controllers ■ Transparently binding form parameters ■ Validating form submissions ■ Mapping exceptions to views Handling web requests 489
490 CHAPTER 13 Handling web requests As a JEE developer, you have more than likely developed a web-based application. In fact, for many Java developers, web-based applications are their primary focus. If you do have this type of experience, you are well aware of the challenges that come with these systems. Specifically, state management, workflow, and validation are all important features that need to be addressed. None of these is made any easier given the HTTP protocol’s stateless nature. Spring’s web framework is designed to help you address these concerns. Based on the Model-View-Controller (MVC) pattern, Spring MVC helps you build webbased applications that are as flexible and as loosely coupled as the Spring Framework itself. In this chapter and the one that follows, we’ll explore the Spring MVC web framework. In this chapter, we’ll focus on the parts of Spring MVC that process requests. You’ll see how to extend Spring’s rich set of controller objects to handle virtually any web functionality required in your application. You’ll also see how Spring’s handler mapping makes easy work of associating URL patterns with specific controller implementations. Chapter 14 will pick up where this chapter leaves off by showing you how to use Spring MVC views to send a response back to the user. Before we go too deep with the specifics of Spring MVC’s controllers and handler mappings, let’s start with a high-level view of Spring MVC and build our first complete bit of web functionality. 13.1 Getting started with Spring MVC Have you ever seen the children’s game Mousetrap? It’s a crazy game. The goal is to send a small steel ball over a series of wacky contraptions in order to trigger a mousetrap. The ball goes over all kinds of intricate gadgets, from rolling down a curvy ramp to getting sprung off a teeter-totter to spinning on a miniature Ferris wheel to being kicked out of a bucket by a rubber boot. It goes through of all of this to spring a trap on a poor, unsuspecting plastic mouse. At first glance, you may think that Spring’s MVC framework is a lot like Mousetrap. Instead of moving a ball around through various ramps, teeter-totters, and wheels, Spring moves requests around between a dispatcher servlet, handler mappings, controllers, and view resolvers. But don’t draw too strong of a comparison between Spring MVC and the Rube Goldberg-esque game of Mousetrap. Each of the components in Spring MVC performs a specific purpose. Let’s start the exploration of Spring MVC by examining the lifecycle of a typical request.
Page 4 and 5: 13.1.1 A day in the life of a reque
Page 6 and 7: Getting started with Spring MVC 493
Page 16 and 17: 13.2.1 Using SimpleUrlHandlerMappin
Page 18 and 19: Mapping requests to controllers 505
Page 20 and 21: Handling requests with controllers
Page 22 and 23: Table 13.2 Spring MVC’s selection
Page 24 and 25: } private RantService rantService;
Page 26 and 27: Listing 13.4 A controller for addin
Page 36 and 37: } Handling requests with controller
Page 44 and 45: Handling exceptions 531 DispatcherS

Sample Chapter 13 - Manning Publications

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