Using themes Web MVC framework

4.3.9.RELEASE Spring Framework 533 bean id = localeChangeInterceptor class = org.springframework.web.servlet.i18n.LocaleChangeInterceptor property name = paramName value = siteLanguage bean bean id = localeResolver class = org.springframework.web.servlet.i18n.CookieLocaleResolver bean id = urlMapping class = org.springframework.web.servlet.handler.SimpleUrlHandlerMapping property name = interceptors list ref bean = localeChangeInterceptor list property property name = mappings value .view=someController value property bean

22.9 Using themes

Overview of themes You can apply Spring Web MVC framework themes to set the overall look-and-feel of your application, thereby enhancing user experience. A theme is a collection of static resources, typically style sheets and images, that affect the visual style of the application. Defining themes To use themes in your web application, you must set up an implementation of the org.springframework.ui.context.ThemeSource interface. The WebApplicationContext interface extends ThemeSource but delegates its responsibilities to a dedicated implementation. By default the delegate will be an org.springframework.ui.context.support.ResourceBundleThemeSource implementation that loads properties files from the root of the classpath. To use a custom ThemeSource implementation or to configure the base name prefix of the ResourceBundleThemeSource , you can register a bean in the application context with the reserved name themeSource . The web application context automatically detects a bean with that name and uses it. When using the ResourceBundleThemeSource , a theme is defined in a simple properties file. The properties file lists the resources that make up the theme. Here is an example: styleSheet=themescoolstyle.css background=themescoolimgcoolBg.jpg The keys of the properties are the names that refer to the themed elements from view code. For a JSP, you typically do this using the spring:theme custom tag, which is very similar to the spring:message tag. The following JSP fragment uses the theme defined in the previous example to customize the look and feel: taglib prefix = spring uri = http:www.springframework.orgtags html head link rel = stylesheet href = spring:theme code=styleSheet type = textcss head body style = background=spring:theme code=background ... body html 4.3.9.RELEASE Spring Framework 534 By default, the ResourceBundleThemeSource uses an empty base name prefix. As a result, the properties files are loaded from the root of the classpath. Thus you would put the cool.properties theme definition in a directory at the root of the classpath, for example, in WEB-INFclasses . The ResourceBundleThemeSource uses the standard Java resource bundle loading mechanism, allowing for full internationalization of themes. For example, we could have a WEB-INFclasses cool_nl.properties that references a special background image with Dutch text on it. Theme resolvers After you define themes, as in the preceding section, you decide which theme to use. The DispatcherServlet will look for a bean named themeResolver to find out which ThemeResolver implementation to use. A theme resolver works in much the same way as a LocaleResolver . It detects the theme to use for a particular request and can also alter the request’s theme. The following theme resolvers are provided by Spring: Table 22.5. ThemeResolver implementations Class Description FixedThemeResolver Selects a fixed theme, set using the defaultThemeName property. SessionThemeResolver The theme is maintained in the user’s HTTP session. It only needs to be set once for each session, but is not persisted between sessions. CookieThemeResolver The selected theme is stored in a cookie on the client. Spring also provides a ThemeChangeInterceptor that allows theme changes on every request with a simple request parameter.

22.10 Spring’s multipart file upload support