Unable to access static resources in JAR file using embedded Jetty - jar

Question

I basically have the same issue as this question:
Setting Jetty resourcebase to static file embedded in the same jar file
where I am using embedded Jetty, and I want to access some static HTML files in the same JAR file.
Here is how the Jetty server is set up:
ServletContextHandler context = new ServletContextHandler(ServletContextHandler.SESSIONS);
context.setContextPath("/");
String res = ApiServer.class.getClassLoader().getResource("res").toExternalForm();
context.setResourceBase(res);
jettyServer = new Server(port);
jettyServer.setHandler(context);
ServletHolder jerseyServlet = context.addServlet(ServletContainer.class, "/*");
jerseyServlet.setInitOrder(0);
// Tells the Jersey Servlet which REST service/class to load.
String classes = new StringJoiner(",")
.add(MyClass1.class.getCanonicalName())
.add(MyClass2.class.getCanonicalName())
.toString();
jerseyServlet.setInitParameter(ServerProperties.PROVIDER_CLASSNAMES, classes);
The folder structure of the JAR is like this:
root
| src (Java classes in here)
| res
| index.html
However it just doesn't work. I have tried to access the URL in various ways:
http://localhost:12345/res/index.html
or
http://localhost:12345/index.html
but neither works.
What am I doing wrong?

Answer 1

The code you have ...
String res = ApiServer.class.getClassLoader().getResource("res").toExternalForm();
context.setResourceBase(res);
Does not work for me, as you cannot use a classloader to obtain a directory reference, only file references. The call ClassLoader.getResource("res") always returns null.
This needs to be fixed first.
Next, your declaration of Jersey is exceedingly greedy.
ServletHolder jerseyServlet = context.addServlet(ServletContainer.class, "/*");
jerseyServlet.setInitOrder(0);
This means that Servlet (ServletContainer.class) is handling 100% of all requests, even requests for static content.
It is impossible for that Servlet, based on your url-pattern, to "not handle" static requests and let Jetty serve those static requests.
Relax this url-pattern, to say /api/* and then you'll be one step closer.
The final thing you need is a DefaultServlet (the component in the Servlet spec, and Jetty that serves static files).
So you'll wind up with the following code ...
ServletContextHandler context = new ServletContextHandler(ServletContextHandler.SESSIONS);
context.setContextPath("/");
URL url = ApiServer.class.getClassLoader().getResource("res/index.html");
if (url == null)
throw new FileNotFoundException("Whoops, can't find static resources folder");
URI webroot = url.toURI().resolve("./");
context.setBaseResource(Resource.newResource(webroot));
ServletHolder jerseyServlet = context.addServlet(ServletContainer.class, "/api/*");
jerseyServlet.setInitOrder(0);
// Tells the Jersey Servlet which REST service/class to load.
String classes = new StringJoiner(",")
.add(MyClass1.class.getCanonicalName())
.add(MyClass2.class.getCanonicalName())
.toString();
jerseyServlet.setInitParameter(ServerProperties.PROVIDER_CLASSNAMES, classes);
// always named "default", always last, always on url-pattern "/"
ServletHolder defaultServ = new ServletHolder("default", DefaultServlet.class);
defaultServ.setInitParameter("dirAllowed","true");
context.addServlet(defaultServ,"/");
jettyServer = new Server(port);
jettyServer.setHandler(context);