rest discoverability work

spring-security-rest/src/main/java/org/baeldung/web/controller/FooController.java

@@ -1,5 +1,7 @@
 package org.baeldung.web.controller;
 
+import java.net.URI;
+
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 
@@ -15,6 +17,7 @@ import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RequestMethod;
 import org.springframework.web.bind.annotation.ResponseBody;
 import org.springframework.web.bind.annotation.ResponseStatus;
+import org.springframework.web.util.UriTemplate;
 
 import com.google.common.base.Preconditions;
 
@@ -47,4 +50,14 @@ public class FooController {
         eventPublisher.publishEvent(new ResourceCreated(this, request, response, idOfCreatedResource));
     }
 
+    @RequestMapping(value = "admin", method = RequestMethod.GET)
+    @ResponseStatus(value = HttpStatus.NO_CONTENT)
+    public void adminRoot(final HttpServletRequest request, final HttpServletResponse response) {
+        final String rootUri = request.getRequestURL().toString();
+
+        final URI fooUri = new UriTemplate("{rootUri}/{resource}").expand(rootUri, "foo");
+        final String linkToFoo = LinkUtil.createLinkHeader(fooUri.toASCIIString(), "collection");
+        response.addHeader("Link", linkToFoo);
+    }
+
 }

spring-security-rest/src/main/java/org/baeldung/web/controller/LinkUtil.java

@@ -0,0 +1,30 @@
+package org.baeldung.web.controller;
+
+import javax.servlet.http.HttpServletResponse;
+
+/**
+ * Provides some constants and utility methods to build a Link Header to be stored in the {@link HttpServletResponse} object
+ */
+public final class LinkUtil {
+
+    private LinkUtil() {
+        throw new AssertionError();
+    }
+
+    //
+
+    /**
+     * Creates a Link Header to be stored in the {@link HttpServletResponse} to provide Discoverability features to the user
+     * 
+     * @param uri
+     *            the base uri
+     * @param rel
+     *            the relative path
+     * 
+     * @return the complete url
+     */
+    public static String createLinkHeader(final String uri, final String rel) {
+        return "<" + uri + ">; rel=\"" + rel + "\"";
+    }
+
+}

spring-security-rest/src/main/java/org/baeldung/web/controller/SingleResourceRetrievedDiscoverabilityListener.java

@@ -25,8 +25,8 @@ class SingleResourceRetrievedDiscoverabilityListener implements ApplicationListe
         final int positionOfLastSlash = requestURL.lastIndexOf("/");
         final String uriForResourceCreation = requestURL.substring(0, positionOfLastSlash);
 
-        // final String linkHeaderValue = RESTURLUtil.createLinkHeader(uriForResourceCreation, "collection");
-        // response.addHeader(LINK_HEADER, linkHeaderValue);
+        final String linkHeaderValue = LinkUtil.createLinkHeader(uriForResourceCreation, "collection");
+        response.addHeader("Link", linkHeaderValue);
     }
 
 }