My web container knows whether my application is running in debug or release mode. I'd like to pass this information to my ResourceConfig/Application class, but it's not clear how to read this information back out.
Is it possible to pass information by way of servlet/filter parameters? If so, how?
Here's how I'm doing it:
in web.xml:
<context-param> <description>When set to true, all operations include debugging info</description> <param-name>com.example.DEBUG_API_ENABLED</param-name> <param-value>true</param-value> </context-param> and in my Application subclass:
@ApplicationPath("api") public class RestApplication extends Application { @Context protected ServletContext sc; @Override public Set<Class<?>> getClasses() { Set<Class<?>> set = new HashSet<Class<?>>(); boolean debugging = Boolean.parseBoolean(sc .getInitParameter("com.example.DEBUG_API_ENABLED")); if (debugging) { // enable debugging resources 
@Provider class from getSingletons).This was fixed in Jersey 2.5: https://java.net/jira/browse/JERSEY-2184
You should now be able to inject @Context ServletContext into the Application constructor.
Here is an example of how this is expected to work:
public class MyApplication extends Application { private final String myInitParameter; public MyApplication(@Context ServletContext servletContext) { this.myInitParameter = servletContext.getInitParameter("myInitParameter"); } } You can also invoke ServiceLocator.getService(ServletContext.class) to get the ServletContext from any point in the application.
In Jersey 1 it was possible to pass @Context ServletContext servletContext to the constructor of an Application class, but in Jersey 2 this no longer works. It seems Jersey 2 will only inject at request time.
To work around this in Jersey 2, use an anonymous ContainerRequestFilter to gain access to a ServletContext at request time and pass the required init parameters into the Application class.
public class MyApplication extends Application { @Context protected ServletContext servletContext; private String myInitParameter; @Override public Set<Object> getSingletons() { Set<Object> singletons = new HashSet<Object>(); singletons.add(new ContainerRequestFilter() { @Override public void filter(ContainerRequestContext containerRequestContext) throws IOException { synchronized(MyApplication.this) { if(myInitParameter == null) { myInitParameter = servletContext.getInitParameter("myInitParameter"); // do any initialisation based on init params here } } } return singletons; }); }; } 