Allow storing values in VaadinSession (#9514)

1 files changed, 109 insertions, 0 deletions

diff --git a/server/src/com/vaadin/server/VaadinSession.java b/server/src/com/vaadin/server/VaadinSession.java
index c6b2d91f29..a91c011ddf 100644
--- a/server/src/com/vaadin/server/VaadinSession.java
+++ b/server/src/com/vaadin/server/VaadinSession.java
@@ -204,6 +204,8 @@ public class VaadinSession implements HttpSessionBindingListener, Serializable {
 
     private transient WrappedSession session;
 
+    private final Map<String, Object> attributes = new HashMap<String, Object>();
+
     /**
      * @see javax.servlet.http.HttpSessionBindingListener#valueBound(HttpSessionBindingEvent)
      */
@@ -1306,4 +1308,111 @@ public class VaadinSession implements HttpSessionBindingListener, Serializable {
         return lock;
     }
 
+    /**
+     * Stores a value in this vaadin session. This can be used to associate data
+     * with the current user so that it can be retrieved at a later point from
+     * some other part of the application. Setting the value to
+     * <code>null</code> clears the stored value.
+     * 
+     * @see #getAttribute(String)
+     * 
+     * @param name
+     *            the name to associate the value with, can not be
+     *            <code>null</code>
+     * @param value
+     *            the value to associate with the name, or <code>null</code> to
+     *            remove a previous association.
+     */
+    public void setAttribute(String name, Object value) {
+        if (name == null) {
+            throw new IllegalArgumentException("name can not be null");
+        }
+        if (value != null) {
+            attributes.put(name, value);
+        } else {
+            attributes.remove(name);
+        }
+    }
+
+    /**
+     * Stores a value in this vaadin session. This can be used to associate data
+     * with the current user so that it can be retrieved at a later point from
+     * some other part of the application. Setting the value to
+     * <code>null</code> clears the stored value.
+     * <p>
+     * The fully qualified name of the type is used as the name when storing the
+     * value. The outcome of calling this method is thus the same as if calling<br />
+     * <br />
+     * <code>setAttribute(type.getName(), value);</code>
+     * 
+     * @see #getAttribute(Class)
+     * @see #setAttribute(String, Object)
+     * 
+     * @param type
+     *            the type that the stored value represents, can not be null
+     * @param value
+     *            the value to associate with the type, or <code>null</code> to
+     *            remove a previous association.
+     */
+    public <T> void setAttribute(Class<T> type, T value) {
+        if (type == null) {
+            throw new IllegalArgumentException("type can not be null");
+        }
+        if (value != null && !type.isInstance(value)) {
+            throw new IllegalArgumentException("value of type "
+                    + type.getName() + " expected but got "
+                    + value.getClass().getName());
+        }
+        setAttribute(type.getName(), value);
+    }
+
+    /**
+     * Gets a stored attribute value. If a value has been stored for the
+     * session, that value is returned. If no value is stored for the name,
+     * <code>null</code> is returned.
+     * 
+     * @see #setAttribute(String, Object)
+     * 
+     * @param name
+     *            the name of the value to get, can not be <code>null</code>.
+     * @return the value, or <code>null</code> if no value has been stored or if
+     *         it has been set to null.
+     */
+    public Object getAttribute(String name) {
+        if (name == null) {
+            throw new IllegalArgumentException("name can not be null");
+        }
+        return attributes.get(name);
+    }
+
+    /**
+     * Gets a stored attribute value. If a value has been stored for the
+     * session, that value is returned. If no value is stored for the name,
+     * <code>null</code> is returned.
+     * <p>
+     * The fully qualified name of the type is used as the name when getting the
+     * value. The outcome of calling this method is thus the same as if calling<br />
+     * <br />
+     * <code>getAttribute(type.getName());</code>
+     * 
+     * @see #setAttribute(Class, Object)
+     * @see #getAttribute(String)
+     * 
+     * @param type
+     *            the type of the value to get, can not be <code>null</code>.
+     * @return the value, or <code>null</code> if no value has been stored or if
+     *         it has been set to null.
+     */
+    public <T> T getAttribute(Class<T> type) {
+        if (type == null) {
+            throw new IllegalArgumentException("type can not be null");
+        }
+        Object value = getAttribute(type.getName());
+        if (value == null) {
+            return null;
+        } else {
+            return type.cast(value);
+        }
+    }
+
 }