Merge pull request #2841 from cyberdelia/json-1.3

Add a JSONUnauthorizedHandler

dropwizard-auth/src/main/java/io/dropwizard/auth/JSONUnauthorizedHandler.java

@@ -0,0 +1,24 @@
+package io.dropwizard.auth;
+
+import io.dropwizard.jersey.errors.ErrorMessage;
+
+import javax.ws.rs.core.HttpHeaders;
+import javax.ws.rs.core.MediaType;
+import javax.ws.rs.core.Response;
+
+public class JSONUnauthorizedHandler implements UnauthorizedHandler {
+    private static final String CHALLENGE_FORMAT = "%s realm=\"%s\"";
+
+    @Override
+    public Response buildResponse(String prefix, String realm) {
+        ErrorMessage errorMessage = new ErrorMessage(
+            Response.Status.UNAUTHORIZED.getStatusCode(),
+            "Credentials are required to access this resource."
+        );
+        return Response.status(errorMessage.getCode())
+            .header(HttpHeaders.WWW_AUTHENTICATE, String.format(CHALLENGE_FORMAT, prefix, realm))
+            .type(MediaType.APPLICATION_JSON_TYPE)
+            .entity(errorMessage)
+            .build();
+    }
+}