vaadin-framework/src/com/itmill/toolkit/demo/CachingDemo.java

/* 
@ITMillApache2LicenseForJavaFiles@
 */

package com.itmill.toolkit.demo;

import com.itmill.toolkit.terminal.PaintException;
import com.itmill.toolkit.terminal.PaintTarget;
import com.itmill.toolkit.ui.Label;
import com.itmill.toolkit.ui.Layout;
import com.itmill.toolkit.ui.OrderedLayout;
import com.itmill.toolkit.ui.TabSheet;
import com.itmill.toolkit.ui.Window;

/**
 * This example is a (simple) demonstration of client-side caching. The content
 * in one tab is intentionally made very slow to produce server-side. When the
 * user changes to this tab for the first time, there will be a 3 second wait
 * before the content shows up, but the second time it shows up immediately
 * since the content has not changed and is cached client-side.
 * 
 * @author IT Mill Ltd.
 */
public class CachingDemo extends com.itmill.toolkit.Application {

    public void init() {

        final Window main = new Window("Client-side caching example");
        setMainWindow(main);

        setTheme("example");

        final TabSheet ts = new TabSheet();
        main.addComponent(ts);

        Layout layout = new OrderedLayout();
        layout.setMargin(true);
        Label l = new Label(
                "This is a normal label, quick to render.<br/>The second tab will be slow to render the first time, after that it will be as quick as this one.");
        l.setCaption("A normal label");
        l.setContentMode(Label.CONTENT_XHTML);
        layout.addComponent(l);

        ts.addTab(layout, "Normal", null);

        layout = new OrderedLayout();
        layout.setMargin(true);
        l = new Label(
                "The first time you change to this tab, this label is very slow to produce (server-side).<br/> However, it will seem fast the second time you change to this tab, because it has not changed and is cached client-side.") {
            public void paintContent(PaintTarget target) throws PaintException {
                try {
                    Thread.sleep(3000);
                } catch (final Exception e) {
                    // IGNORED
                }
                super.paintContent(target);
            }

        };
        l.setCaption("A slow label");
        l.setContentMode(Label.CONTENT_XHTML);
        layout.addComponent(l);
        ts.addTab(layout, "Slow", null);

    }

}