Update location when initialized UI is opened again (#10044)

* Also fix Page.updateLocation to avoid NPE if fragment changes from
null to null

Change-Id: I03f3883c2653eaf438ccdfc313078fbe8fe898bc

2 files changed, 22 insertions, 3 deletions

diff --git a/server/src/com/vaadin/server/AbstractCommunicationManager.java b/server/src/com/vaadin/server/AbstractCommunicationManager.java
index 43a9ced608..c3a6213265 100644
--- a/server/src/com/vaadin/server/AbstractCommunicationManager.java
+++ b/server/src/com/vaadin/server/AbstractCommunicationManager.java
@@ -61,6 +61,7 @@ import org.json.JSONException;
 import org.json.JSONObject;
 
 import com.vaadin.annotations.JavaScript;
+import com.vaadin.annotations.PreserveOnRefresh;
 import com.vaadin.annotations.StyleSheet;
 import com.vaadin.server.ComponentSizeValidator.InvalidLayout;
 import com.vaadin.server.RpcManager.RpcInvocationException;
@@ -2467,7 +2468,7 @@ public abstract class AbstractCommunicationManager implements Serializable {
                 UI existingUi = legacyProvider
                         .getExistingUI(classSelectionEvent);
                 if (existingUi != null) {
-                    UI.setCurrent(existingUi);
+                    reinitUI(existingUi, request);
                     return existingUi;
                 }
             }
@@ -2498,6 +2499,7 @@ public abstract class AbstractCommunicationManager implements Serializable {
             if (retainedUIId != null) {
                 UI retainedUI = session.getUIById(retainedUIId.intValue());
                 if (uiClass.isInstance(retainedUI)) {
+                    reinitUI(retainedUI, request);
                     return retainedUI;
                 } else {
                     getLogger()
@@ -2547,6 +2549,23 @@ public abstract class AbstractCommunicationManager implements Serializable {
     }
 
     /**
+     * Updates a UI that has already been initialized but is now loaded again,
+     * e.g. because of {@link PreserveOnRefresh}.
+     * 
+     * @param ui
+     * @param request
+     */
+    private void reinitUI(UI ui, VaadinRequest request) {
+        UI.setCurrent(ui);
+
+        // Fire fragment change if the fragment has changed
+        String location = request.getParameter("loc");
+        if (location != null) {
+            ui.getPage().updateLocation(location);
+        }
+    }
+
+    /**
      * Generates the initial UIDL message that can e.g. be included in a html
      * page to avoid a separate round trip just for getting the UIDL.
      * 
diff --git a/server/src/com/vaadin/server/Page.java b/server/src/com/vaadin/server/Page.java
index 1f4ff040ac..ab8c591b13 100644
--- a/server/src/com/vaadin/server/Page.java
+++ b/server/src/com/vaadin/server/Page.java
@@ -657,8 +657,8 @@ public class Page implements Serializable {
             String oldFragment = this.location.getFragment();
             this.location = new URI(location);
             String newFragment = this.location.getFragment();
-            if (newFragment == null && oldFragment != null
-                    || !newFragment.equals(oldFragment)) {
+            if (newFragment == null ? oldFragment != null : !newFragment
+                    .equals(oldFragment)) {
                 fireEvent(new FragmentChangedEvent(this, newFragment));
             }
         } catch (URISyntaxException e) {