CreatingPreserveState.java

/*
 * 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.tests.minitutorials.v7a1;

import com.vaadin.annotations.PreserveOnRefresh;
import com.vaadin.server.VaadinRequest;
import com.vaadin.ui.CssLayout;
import com.vaadin.ui.Label;
import com.vaadin.ui.UI;
import com.vaadin.v7.ui.TextField;

/**
 * Mini tutorial code for
 * https://vaadin.com/wiki/-/wiki/Main/Creating%20an%20application
 * %20that%20preserves%20state%20on%20refresh
 *
 * @author Vaadin Ltd
 * @since 7.0.0
 */
@PreserveOnRefresh
public class CreatingPreserveState extends UI {
    private static int instanceCounter = 0;

    private final CssLayout content = new CssLayout();

    @Override
    public void init(VaadinRequest request) {
        TextField tf = new TextField("Instance #" + (++instanceCounter));
        tf.setImmediate(true);

        content.addComponent(tf);
        setContent(content);
    }

    @Override
    protected void refresh(VaadinRequest request) {
        content.addComponent(
                new Label("UI was refreshed @" + System.currentTimeMillis()));
    }
}