From 5c2a9918e091f526ba2e17e2c70f8bcbbf47c1f5 Mon Sep 17 00:00:00 2001
From: Artur Signell <artur@vaadin.com>
Date: Tue, 3 Apr 2012 00:29:44 +0300
Subject: [PATCH] Automatically create state on server side based on getState
 return type

---
 src/com/vaadin/ui/AbstractComponent.java  | 34 +++++++++++++++++++----
 src/com/vaadin/ui/AbstractField.java      |  4 ---
 src/com/vaadin/ui/AbstractSplitPanel.java |  5 ----
 src/com/vaadin/ui/Button.java             |  6 ----
 src/com/vaadin/ui/Panel.java              |  4 ---
 src/com/vaadin/ui/Window.java             |  4 ---
 6 files changed, 28 insertions(+), 29 deletions(-)

diff --git a/src/com/vaadin/ui/AbstractComponent.java b/src/com/vaadin/ui/AbstractComponent.java
index 189142519d..8c26911a9a 100644
--- a/src/com/vaadin/ui/AbstractComponent.java
+++ b/src/com/vaadin/ui/AbstractComponent.java
@@ -18,6 +18,8 @@ import java.util.LinkedList;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
+import java.util.logging.Level;
+import java.util.logging.Logger;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
@@ -879,18 +881,34 @@ public abstract class AbstractComponent implements Component, MethodEventSource
     /**
      * Creates the shared state bean to be used in server to client
      * communication.
-     * 
-     * Subclasses should implement this method and return a new instance of the
-     * correct state class.
-     * 
-     * All configuration of the values of the state should be performed in
-     * {@link #getState()}, not in {@link #createState()}.
+     * <p>
+     * By default a state object of the defined return type of
+     * {@link #getState()} is created. Subclasses can override this method and
+     * return a new instance of the correct state class but this should rarely
+     * be necessary.
+     * </p>
+     * <p>
+     * No configuration of the values of the state should be performed in
+     * {@link #createState()}.
      * 
      * @since 7.0
      * 
      * @return new shared state object
      */
     protected ComponentState createState() {
+        try {
+            Method m = getClass().getMethod("getState", (Class[]) null);
+            Class<? extends ComponentState> type = (Class<? extends ComponentState>) m
+                    .getReturnType();
+            return type.newInstance();
+        } catch (Exception e) {
+            getLogger().log(
+                    Level.INFO,
+                    "Error determining state object class for "
+                            + getClass().getName());
+        }
+
+        // Fall back to ComponentState if detection fails for some reason.
         return new ComponentState();
     }
 
@@ -1743,4 +1761,8 @@ public abstract class AbstractComponent implements Component, MethodEventSource
         }
         return connectorId;
     }
+
+    private Logger getLogger() {
+        return Logger.getLogger(AbstractComponent.class.getName());
+    }
 }
diff --git a/src/com/vaadin/ui/AbstractField.java b/src/com/vaadin/ui/AbstractField.java
index aecb07e108..361e65fa34 100644
--- a/src/com/vaadin/ui/AbstractField.java
+++ b/src/com/vaadin/ui/AbstractField.java
@@ -1592,8 +1592,4 @@ public abstract class AbstractField<T> extends AbstractComponent implements
         getState().setHideErrors(shouldHideErrors());
     }
 
-    @Override
-    protected AbstractFieldState createState() {
-        return new AbstractFieldState();
-    }
 }
diff --git a/src/com/vaadin/ui/AbstractSplitPanel.java b/src/com/vaadin/ui/AbstractSplitPanel.java
index 2e31436ee2..b576008344 100644
--- a/src/com/vaadin/ui/AbstractSplitPanel.java
+++ b/src/com/vaadin/ui/AbstractSplitPanel.java
@@ -11,7 +11,6 @@ import java.util.Iterator;
 import com.vaadin.event.ComponentEventListener;
 import com.vaadin.event.MouseEvents.ClickEvent;
 import com.vaadin.terminal.Sizeable;
-import com.vaadin.terminal.gwt.client.ComponentState;
 import com.vaadin.terminal.gwt.client.MouseEventDetails;
 import com.vaadin.terminal.gwt.client.ui.AbstractSplitPanelConnector.AbstractSplitPanelRPC;
 import com.vaadin.terminal.gwt.client.ui.AbstractSplitPanelConnector.AbstractSplitPanelState;
@@ -388,8 +387,4 @@ public abstract class AbstractSplitPanel extends AbstractLayout {
         return (AbstractSplitPanelState) super.getState();
     }
 
-    @Override
-    protected ComponentState createState() {
-        return new AbstractSplitPanelState();
-    }
 }
diff --git a/src/com/vaadin/ui/Button.java b/src/com/vaadin/ui/Button.java
index 7deb048655..5c66d57939 100644
--- a/src/com/vaadin/ui/Button.java
+++ b/src/com/vaadin/ui/Button.java
@@ -18,7 +18,6 @@ import com.vaadin.event.ShortcutAction;
 import com.vaadin.event.ShortcutAction.KeyCode;
 import com.vaadin.event.ShortcutAction.ModifierKey;
 import com.vaadin.event.ShortcutListener;
-import com.vaadin.terminal.gwt.client.ComponentState;
 import com.vaadin.terminal.gwt.client.MouseEventDetails;
 import com.vaadin.terminal.gwt.client.ui.ButtonConnector.ButtonServerRpc;
 import com.vaadin.terminal.gwt.client.ui.ButtonState;
@@ -496,11 +495,6 @@ public class Button extends AbstractComponent implements
         super.focus();
     }
 
-    @Override
-    protected ComponentState createState() {
-        return new ButtonState();
-    }
-
     @Override
     public ButtonState getState() {
         return (ButtonState) super.getState();
diff --git a/src/com/vaadin/ui/Panel.java b/src/com/vaadin/ui/Panel.java
index 26c7e63908..ad0ff4222f 100644
--- a/src/com/vaadin/ui/Panel.java
+++ b/src/com/vaadin/ui/Panel.java
@@ -546,8 +546,4 @@ public class Panel extends AbstractComponentContainer implements Scrollable,
         return (PanelState) super.getState();
     }
 
-    @Override
-    protected PanelState createState() {
-        return new PanelState();
-    }
 }
diff --git a/src/com/vaadin/ui/Window.java b/src/com/vaadin/ui/Window.java
index aa49a36b55..f15b46ce1d 100644
--- a/src/com/vaadin/ui/Window.java
+++ b/src/com/vaadin/ui/Window.java
@@ -903,8 +903,4 @@ public class Window extends Panel implements FocusNotifier, BlurNotifier {
         return (WindowState) super.getState();
     }
 
-    @Override
-    protected WindowState createState() {
-        return new WindowState();
-    }
 }
-- 
2.39.5