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.
as of 6.0 support for themes has been deprecated theme in favor of using CSS, and without any special support on the server side. |
Defining a theme
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 is 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 you use the ResourceBundleThemeSource
, a theme is defined in a simple properties
file. The properties file lists the resources that make up the theme, as the following example shows:
styleSheet=/themes/cool/style.css background=/themes/cool/img/coolBg.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.org/tags"%>
<html>
<head>
<link rel="stylesheet" href="<spring:theme code='styleSheet'/>" type="text/css"/>
</head>
<body style="background=<spring:theme code='background'/>">
...
</body>
</html>
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-INF/classes
). The ResourceBundleThemeSource
uses the standard Java
resource bundle loading mechanism, allowing for full internationalization of themes. For
example, we could have a /WEB-INF/classes/cool_nl.properties
that references a special
background image with Dutch text on it.
Resolving Themes
After you define themes, as described in the preceding section,
you decide which theme to use. The DispatcherServlet
looks 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 table describes the theme resolvers provided by Spring:
Class | Description |
---|---|
|
Selects a fixed theme, set by using the |
|
The theme is maintained in the user’s HTTP session. It needs to be set only once for each session but is not persisted between sessions. |
|
The selected theme is stored in a cookie on the client. |
Spring also provides a ThemeChangeInterceptor
that lets theme changes on every
request with a simple request parameter.