Application settings

How the application starts

A Wicket application is a Jakarta web application. The servlet container starts a WicketFilter, which creates the application object, calls its initialization, and then handles every request mapped to the filter. WicketServlet does the same as a servlet, for containers or setups where a filter does not fit.

web.xml

<filter>
    <filter-name>wicket.myproject</filter-name>
    <filter-class>org.apache.wicket.protocol.http.WicketFilter</filter-class>
    <init-param>
        <param-name>applicationClassName</param-name>
        <param-value>com.mycompany.WicketApplication</param-value>
    </init-param>
</filter>
<filter-mapping>
    <filter-name>wicket.myproject</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

Without web.xml, annotate a subclass of WicketFilter:

ProjectFilter.java

@WebFilter(value = "/*", initParams = {
        @WebInitParam(name = "applicationClassName", value = "com.mycompany.WicketApplication"),
        @WebInitParam(name = "filterMappingUrlPattern", value = "/*") })
public class ProjectFilter extends WicketFilter {
}

Filter parameters

Initialization order

When the filter starts, Application.initApplication() runs these steps:

Your init() runs after Wicket’s defaults, so a setting you change there sticks.

Application class

You extend WebApplication and override:

Application.get() returns the application of the current thread anywhere in request processing; WebApplication.get() returns it as a WebApplication.

Settings objects

The application groups its settings in objects you get from getter methods, usually in init():

@Override
protected void init() {
    super.init();
    getMarkupSettings().setStripWicketTags(true);
    getApplicationSettings().setPageExpiredErrorPage(SessionExpiredPage.class);
}

Each setter returns its settings object, so calls on one object can be chained. The tables list the main options; see the Javadoc of each class for all of them.

ApplicationSettings

getApplicationSettings(): error pages, uploads and class loading.

DebugSettings

getDebugSettings(): checks and aids for development.

“(mode)” marks a setting that the runtime configuration type overwrites, see Development and deployment defaults.

ExceptionSettings

getExceptionSettings(): what happens on unexpected exceptions.

FrameworkSettings

getFrameworkSettings(): framework-wide hooks.

JavaScriptLibrarySettings

getJavaScriptLibrarySettings(): the JavaScript Wicket loads for Ajax.

MarkupSettings

getMarkupSettings(): how markup is read and written.

PageSettings

getPageSettings(): pages and their versions.

RequestCycleSettings

getRequestCycleSettings(): how requests are handled and responses written.

RequestLoggerSettings

getRequestLoggerSettings(): the request logger.

ResourceSettings

getResourceSettings(): markup, resources and resource bundles.

SecuritySettings

getSecuritySettings(): authorization, encryption and isolation headers.

Encryption in Wicket describes the encryption settings of both release lines.

StoreSettings

getStoreSettings(): where pages are kept between requests.

Content security policy

getCspSettings() on WebApplication returns the ContentSecurityPolicySettings. blocking() and reporting() return the configuration of the enforced and the report-only header, to which you add directives. Wicket sets a strict policy with a nonce for scripts and styles by default. See Configure the Content Security Policy.

Listener collections

Application also holds collections of listeners, each with an add method:

Runtime configuration type

RuntimeConfigurationType has two values, DEVELOPMENT and DEPLOYMENT. WebApplication.getConfigurationType() takes the first value it finds:

1. The system property wicket.configuration.
2. The filter or servlet parameter wicket.configuration.
3. The context parameter wicket.configuration.
4. The filter or servlet parameter configuration.
5. The context parameter configuration.
6. DEVELOPMENT.

The value is not case-sensitive. An override of getConfigurationType() replaces this lookup. Switch between development and deployment mode shows each way.

Development and deployment defaults

During initialization, Wicket sets these settings according to the runtime configuration type. A value you set in init() replaces them.