Make VaadinServlet use enclosing UI class by default (#12039)

Change-Id: Ica2b9b9d82ef6d683cb51f3478a07e57cbfa28e5

1 files changed, 12 insertions, 0 deletions

diff --git a/server/src/com/vaadin/server/VaadinServlet.java b/server/src/com/vaadin/server/VaadinServlet.java
index a3030c9d8d..a9eb42578e 100644
--- a/server/src/com/vaadin/server/VaadinServlet.java
+++ b/server/src/com/vaadin/server/VaadinServlet.java
@@ -44,6 +44,7 @@ import com.vaadin.annotations.VaadinServletConfiguration.InitParameterName;
 import com.vaadin.sass.internal.ScssStylesheet;
 import com.vaadin.server.communication.ServletUIInitHandler;
 import com.vaadin.shared.JsonConstants;
+import com.vaadin.ui.UI;
 import com.vaadin.util.CurrentInstance;
 
 @SuppressWarnings("serial")
@@ -69,6 +70,8 @@ public class VaadinServlet extends HttpServlet implements Constants {
         super.init(servletConfig);
         Properties initParameters = new Properties();
 
+        readUiFromEnclosingClass(initParameters);
+
         readConfigurationAnnotation(initParameters);
 
         // Read default parameters from server.xml
@@ -101,6 +104,15 @@ public class VaadinServlet extends HttpServlet implements Constants {
         CurrentInstance.clearAll();
     }
 
+    private void readUiFromEnclosingClass(Properties initParameters) {
+        Class<?> enclosingClass = getClass().getEnclosingClass();
+
+        if (enclosingClass != null && UI.class.isAssignableFrom(enclosingClass)) {
+            initParameters.put(VaadinSession.UI_PARAMETER,
+                    enclosingClass.getName());
+        }
+    }
+
     private void readConfigurationAnnotation(Properties initParameters)
             throws ServletException {
         VaadinServletConfiguration configAnnotation = UIProvider