Dynamic servlet mapping
Servlet
mapping specifies which servlet should be invoked when the client
requests a particular URL. In Magnolia, servlet mappings are typically
configured in /server/filters/servlets. This is a static way. While
creating a component (Java class or Freemarker script), the path to a
servlet is hard-coded. When the mapping changes, the hard-coded string
literal must be changed too and the software must be re-deployed. To
work around this limitation, use dynamic servlet mapping. WARNING:
Magnolia 5.3+
Dynamic mapping with SelfMappingServlet
The info.magnolia.cms.filters.SelfMappingServlet interface makes dynamic servlet mapping possible. The interface has one method:
String getSelfMappingPath();Implement the interface in your own servlet. Instead of returning a hard-coded literal, return something originating in a configuration. Any other Java class such as a model class used in a Freemarker script can then read the value.
Example: DamDownloadServlet
Other components in the system may need to know about servlet mappings.
This is the case when generating links for the DAM servlet.
DamDownloadServlet
implements the SelfMappingServlet interface:
info.magnolia.dam.core.download.DamDownloadServlet
public class DamDownloadServlet extends HttpServlet implements SelfMappingServlet {
// ... more code here (this is just a snippet)
@Inject
public DamDownloadServlet(final DamCoreConfiguration configuration, final AssetProviderRegistry assetProviderRegistry) {
this.configuration = configuration;
this.assetProviderRegistry = assetProviderRegistry;
}
@Override
public String getSelfMappingPath() {
return configuration.getDownloadPath() + "/*";
}
}The getSelfMappingPath() method returns a value which comes from the
DamCoreConfiguration - which could be injected into any other class,
too. DamCoreConfiguration#getDownloadPath() is also used in
JcrAssetProvider
to construct paths for links:
info.magnolia.dam.jcr.JcrAssetProvider
// ... more code here (this is just a snippet)
public String getLink(final Asset asset) {
final String contextPath = MgnlContext.getContextPath();
return contextPath + configuration.getDownloadPath() + asset.getItemKey().asString() + "/" + asset.getFileName();
}If for whatever reason the mapped path to the DamDownloadServlet must
be changed, there is only one place where the path is adapted:
/modules/dam/config/downloadPath in module configuration. The code of
DamDownloadServlet and JcrAssetProvider remain the same. This means
you don’t need to re-deploy the application. You only need to change
configuration on the running system.
You won’t find anything at /modules/dam/config/downloadPath
because DamCoreConfiguration#getDownloadPath() has a default value.
|