[[creating-an-application-that-preserves-state-on-refresh]] Creating an application that preserves state on refresh ------------------------------------------------------- By default, Vaadin 7 does not preserve UI state when the browser page is refreshed. This means that the instance number in this example is incremented and the text field cleared on every page refresh: [source,java] .... 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); } } .... You can however modify your application to preserve your UI between page refreshes with the `@PreserveOnRefresh` annotation like so [source,java] .... @PreserveOnRefresh public class PreserveStateUI extends UI { ... } .... If you want to reinitialize some part of your application when the page is refreshed, you can (starting from Vaadin 7.2) override the refresh method in your UI class. This method is called whenever an already initialized UI is refreshed. [source,java] .... @Override protected void refresh(VaadinRequest request) { content.addComponent(new Label("UI was refreshed @" + System.currentTimeMillis())); } .... ue='Temp_ChangeBars'>Temp_ChangeBars Apache XML Graphics FOP: https://github.com/apache/xmlgraphics-fopwww-data
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path: root/examples/embedding/java/embedding/ExampleDOM2PDF.java
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/*
 * Copyright 1999-2004 The Apache Software Foundation.
 * 
 * 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.
 */

/* $Id$ */
 
package embedding;

// Java
import java.io.File;
import java.io.IOException;
import java.io.OutputStream;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.DocumentBuilder;

//JAXP
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.Source;
import javax.xml.transform.Result;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.sax.SAXResult;

// DOM
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.Text;

// FOP
import org.apache.fop.apps.Fop;
import org.apache.fop.apps.MimeConstants;


/**
 * This class demonstrates the conversion of a DOM Document to PDF
 * using JAXP (XSLT) and FOP (XSL-FO).
 */
public class ExampleDOM2PDF {

    /** xsl-fo namespace URI */
    protected static String foNS = "http://www.w3.org/1999/XSL/Format";

    /**
     * Converts a DOM Document to a PDF file using FOP.
     * @param xslfoDoc the DOM Document
     * @param pdf the target PDF file
     * @throws IOException In case of an I/O problem
     * @throws FOPException In case of a FOP problem
     */
    public void convertDOM2PDF(Document xslfoDoc, File pdf) {
        try {
            // Construct fop with desired output format
            Fop fop = new Fop(MimeConstants.MIME_PDF);
            
            // Setup output
            OutputStream out = new java.io.FileOutputStream(pdf);
            out = new java.io.BufferedOutputStream(out);
    
            try {
                fop.setOutputStream(out);
                
                // Setup Identity Transformer
                TransformerFactory factory = TransformerFactory.newInstance();
                Transformer transformer = factory.newTransformer(); // identity transformer
                
                // Setup input for XSLT transformation
                Source src = new DOMSource(xslfoDoc);
                
                // Resulting SAX events (the generated FO) must be piped through to FOP
                Result res = new SAXResult(fop.getDefaultHandler());
                
                // Start XSLT transformation and FOP processing
                transformer.transform(src, res);
            } finally {
                out.close();
            }
            
        } catch (Exception e) {
            e.printStackTrace(System.err);
            System.exit(-1);
        }

    }

    /**
     * Main method.
     * @param args command-line arguments
     */
    public static void main(String[] args) {
        try {
            System.out.println("FOP ExampleDOM2PDF\n");
            
            //Setup directories
            File baseDir = new File(".");
            File outDir = new File(baseDir, "out");
            outDir.mkdirs();
            
            //Setup output file
            File pdffile = new File(outDir, "ResultDOM2PDF.pdf");
            System.out.println("PDF Output File: " + pdffile);
            System.out.println();
            
            // Create a sample XSL-FO DOM document
            Document foDoc = null;
            Element root = null, ele1 = null, ele2 = null, ele3 = null;
            
            DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
            dbf.setNamespaceAware(true);
            DocumentBuilder db = dbf.newDocumentBuilder();
            foDoc = db.newDocument();
            
            root = foDoc.createElementNS(foNS, "fo:root");
            foDoc.appendChild(root);
            
            ele1 = foDoc.createElementNS(foNS, "fo:layout-master-set");
            root.appendChild(ele1);
            ele2 = foDoc.createElementNS(foNS, "fo:simple-page-master");
            ele1.appendChild(ele2);
            ele2.setAttributeNS(null, "master-name", "letter");
            ele2.setAttributeNS(null, "page-height", "11in");
            ele2.setAttributeNS(null, "page-width", "8.5in");
            ele2.setAttributeNS(null, "margin-top", "1in");
            ele2.setAttributeNS(null, "margin-bottom", "1in");
            ele2.setAttributeNS(null, "margin-left", "1in");
            ele2.setAttributeNS(null, "margin-right", "1in");
            ele3 = foDoc.createElementNS(foNS, "fo:region-body");
            ele2.appendChild(ele3);
            ele1 = foDoc.createElementNS(foNS, "fo:page-sequence");
            root.appendChild(ele1);
            ele1.setAttributeNS(null, "master-reference", "letter");
            ele2 = foDoc.createElementNS(foNS, "fo:flow");
            ele1.appendChild(ele2);
            ele2.setAttributeNS(null, "flow-name", "xsl-region-body");
            addElement(ele2, "fo:block", "Hello World!");
            
            ExampleDOM2PDF app = new ExampleDOM2PDF();
            app.convertDOM2PDF(foDoc, pdffile);
            
            System.out.println("Success!");
            
        } catch (Exception e) {
            e.printStackTrace(System.err);
            System.exit(-1);
        }
    }

    /**
     * Adds an element to the DOM.
     * @param parent parent node to attach the new element to
     * @param newNodeName name of the new node
     * @param textVal content of the element
     */
    protected static void addElement(Node parent, String newNodeName, 
                                String textVal) {
        if (textVal == null) {
            return;
        }  // use only with text nodes
        Element newElement = parent.getOwnerDocument().createElementNS(
                                        foNS, newNodeName);
        Text elementText = parent.getOwnerDocument().createTextNode(textVal);
        newElement.appendChild(elementText);
        parent.appendChild(newElement);
    }
}