/*
* Copyright 2000-2016 Vaadin Ltd.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package com.vaadin.annotations;
import java.lang.annotation.ElementType;
import java.lang.annotation.Inherited;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import com.vaadin.server.UIProvider;
import com.vaadin.ui.UI;
/**
* Marks a UI that should be retained when the user refreshed the browser
* window. By default, a new UI instance is created when refreshing, causing any
* UI state not captured in the URL or the URI fragment to get discarded. By
* adding this annotation to a UI class, the framework will instead reuse the
* current UI instance when a reload is detected.
* <p>
* Whenever a request is received that reloads a preserved UI, the UI's
* {@link UI#refresh(com.vaadin.server.VaadinRequest) refresh} method is invoked
* by the framework.
* <p>
* By using
* {@link UIProvider#isPreservedOnRefresh(com.vaadin.server.UICreateEvent)}, the
* decision can also be made dynamically based on other parameters than only
* whether this annotation is present on the UI class.
*
* @author Vaadin Ltd
* @since 7.0.0
*/
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Inherited
public @interface PreserveOnRefresh {
// Empty marker annotation
}