Customize where resources are loaded from

Add a resource finder when markup files, properties files or package resources should live somewhere other than next to the classes, for example in a folder that designers edit or that a theme replaces.

Where Wicket looks by default

Wicket looks up a file such as com/example/HomePage.html with a list of resource finders, in order, and takes the first match:

1. the classpath, ClassPathResourceFinder("");
2. the root of the web application, WebApplicationPath(servletContext, "");
3. META-INF/resources/ on the classpath, ClassPathResourceFinder("META-INF/resources/").

In a Maven project, files under src/main/resources end up on the classpath, so src/main/resources/com/example/HomePage.html is found by the first finder without configuration.

Add a folder in the web application

Create a WebApplicationPath for the folder and add it to the list in init(). The folder must repeat the package structure:

src/main/webapp/
    markup/
        com/example/
            HomePage.html
            HomePage.properties

WicketApplication.java

@Override
protected void init() {
    super.init();
    getResourceSettings().getResourceFinders()
        .add(0, new WebApplicationPath(getServletContext(), "markup"));
}

Adding at index 0 makes the folder win over a file with the same name on the classpath, so a folder can override the markup of a component. Use add(finder) instead to search the folder only when the classpath has no match. WebApplicationPath never loads files under WEB-INF.

Everything Wicket looks up by class and name goes through these finders: markup, properties files and package resources such as CSS and images. The package resource guard still decides which package files found in a folder are served, see Control which package resources are served.

Add a folder on the file system

Path searches a folder on disk. The folder must exist when the application starts:

getResourceSettings().getResourceFinders()
    .add(0, new Path("/srv/example/templates"));

During development, a Path at index 0 that points at your source folder makes edits to markup show up without a rebuild: in development mode Wicket checks loaded markup files for changes every second and reloads them.

if (usesDevelopmentConfig()) {
    getResourceSettings().getResourceFinders()
        .add(0, new Path("/home/me/projects/example/src/main/java"));
}

The sourceFolder init parameter of the Wicket filter also adds a Path in development mode, but at the end of the list, so it only finds files that are not on the classpath.

Write your own finder

IResourceFinder has one method, find(Class<?> clazz, String pathname), which returns an IResourceStream or null. Implement it to load files from a database or a remote store, and add it to the list like the finders above.

To replace the lookup as a whole, including the way locale, style and variation are combined into file names, set an IResourceStreamLocator with getResourceSettings().setResourceStreamLocator(…). Wrap your locator in a CachingResourceStreamLocator, as Wicket does with its own, or every lookup goes to your source again. Where Wicket looks for texts shows how locale and style become part of the names that the finders receive.