Java GUI to display webpages and return HTML

Question

I need a workflow like below:

// load xyz.com in the browser window
// the browser is live, meaning users can interact with it
browser.load("http://www.google.com");

// return the HTML of the initially loaded page
String page = browser.getHTML();

// after some time
// user might have navigated to a new page, get HTML again
String newpage = browser.getHTML();

I am surprised to see how hard this is to do with Java GUIs such as JavaFX (http://lexandera.com/2009/01/extracting-html-from-a-webview/) and Swing.

Is there some simple way to get this functionality in Java?

Answer 1

Here is a contrived example using JavaFX that prints the html content to System.out - it should not be too complicated to adapt to create a getHtml() method. (I have tested it with JavaFX 8 but it should work with JavaFX 2 too).

The code will print the HTML content everytime a new page is loaded.

Note: I have borrowed the printDocument code from this answer.

public class TestFX extends Application {

    @Override
    public void start(Stage stage) throws Exception {
        try {
            final WebView webView = new WebView();
            final WebEngine webEngine = webView.getEngine();

            Scene scene = new Scene(webView);

            stage.setScene(scene);
            stage.setWidth(1200);
            stage.setHeight(600);
            stage.show();

            webEngine.getLoadWorker().stateProperty().addListener(new ChangeListener<Worker.State>() {
                @Override
                public void changed(ObservableValue<? extends State> ov, State t, State t1) {
                    if (t1 == Worker.State.SUCCEEDED) {
                        try {
                            printDocument(webEngine.getDocument(), System.out);
                        } catch (Exception e) { e.printStackTrace(); }
                    }
                }
            });

            webView.getEngine().load("http://www.google.com");

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static void printDocument(Document doc, OutputStream out) throws IOException, TransformerException {
        TransformerFactory tf = TransformerFactory.newInstance();
        Transformer transformer = tf.newTransformer();
        transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "no");
        transformer.setOutputProperty(OutputKeys.METHOD, "xml");
        transformer.setOutputProperty(OutputKeys.INDENT, "yes");
        transformer.setOutputProperty(OutputKeys.ENCODING, "UTF-8");
        transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "4");
        transformer.transform(new DOMSource(doc), new StreamResult(new OutputStreamWriter(out, "UTF-8")));
    }

    public static void main(String[] args) {
        launch(args);
    }
}

Answer 2

Below you will find a SimpleBrowser component which is a Pane containing a WebView.

Source code at gist.

Sample usage:

SimpleBrowser browser = new SimpleBrowser()
          .useFirebug(true);    

// ^ useFirebug(true) option - will enable Firebug Lite which can be helpful for 
// | debugging - i.e. to inspect a DOM tree or to view console messages 

Scene scene = new Scene(browser);

browser.load("http://stackoverflow.com", new Runnable() {
    @Override
    public void run() {
        System.out.println(browser.getHTML());
    }
});

browser.getHTML() is put inside a Runnable because one needs to wait for a web page to download and render. Trying to invoke this method before page loading will return an empty page, so wrapping this into a runnable is a simple way I came up with to wait for a page to load.

import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.concurrent.Worker;
import javafx.scene.layout.*;
import javafx.scene.web.WebEngine;
import javafx.scene.web.WebView;

public class SimpleBrowser extends Pane {
    protected final WebView webView = new WebView();
    protected final WebEngine webEngine = webView.getEngine();

    protected boolean useFirebug;

    public WebView getWebView() {
        return webView;
    }

    public WebEngine getEngine() {
        return webView.getEngine();
    }

    public SimpleBrowser load(String location) {
        return load(location, null);
    }

    public SimpleBrowser load(String location, final Runnable onLoad) {
        webEngine.load(location);

        webEngine.getLoadWorker().stateProperty().addListener(new ChangeListener<Worker.State>() {
            @Override
            public void changed(ObservableValue<? extends Worker.State> ov, Worker.State t, Worker.State t1) {
                if (t1 == Worker.State.SUCCEEDED) {
                    if(useFirebug){
                        webEngine.executeScript("if (!document.getElementById('FirebugLite')){E = document['createElement' + 'NS'] && document.documentElement.namespaceURI;E = E ? document['createElement' + 'NS'](E, 'script') : document['createElement']('script');E['setAttribute']('id', 'FirebugLite');E['setAttribute']('src', 'https://getfirebug.com/' + 'firebug-lite.js' + '#startOpened');E['setAttribute']('FirebugLite', '4');(document['getElementsByTagName']('head')[0] || document['getElementsByTagName']('body')[0]).appendChild(E);E = new Image;E['setAttribute']('src', 'https://getfirebug.com/' + '#startOpened');}");
                    }
                    if(onLoad != null){
                        onLoad.run();
                    }
                }
            }
        });

        return this;
    }

    public String getHTML() {
        return (String)webEngine.executeScript("document.getElementsByTagName('html')[0].innerHTML");
    }

    public SimpleBrowser useFirebug(boolean useFirebug) {
        this.useFirebug = useFirebug;
        return this;
    }

    public SimpleBrowser() {
        this(false);
    }

    public SimpleBrowser(boolean useFirebug) {
        this.useFirebug = useFirebug;

        getChildren().add(webView);

        webView.prefWidthProperty().bind(widthProperty());
        webView.prefHeightProperty().bind(heightProperty());
    }
}

Demo Browser:

import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.TextField;
import javafx.scene.layout.HBox;
import javafx.scene.layout.Priority;
import javafx.scene.layout.VBox;
import javafx.scene.layout.VBoxBuilder;
import javafx.stage.Stage;

public class FXBrowser {
    public static class TestOnClick extends Application {


        @Override
        public void start(Stage stage) throws Exception {
            try {
                SimpleBrowser browser = new SimpleBrowser()
                    .useFirebug(true);

                final TextField location = new TextField("http://stackoverflow.com");

                Button go = new Button("Go");

                go.setOnAction(new EventHandler<ActionEvent>() {
                    @Override
                    public void handle(ActionEvent arg0) {
                        browser.load(location.getText(), new Runnable() {
                            @Override
                            public void run() {
                                System.out.println("---------------");
                                System.out.println(browser.getHTML());
                            }
                        });
                    }
                });


                HBox toolbar  = new HBox();
                toolbar.getChildren().addAll(location, go);

                toolbar.setFillHeight(true);

                VBox vBox = VBoxBuilder.create().children(toolbar, browser)
                    .fillWidth(true)
                    .build();


                Scene scene = new Scene( vBox);

                stage.setScene(scene);
                stage.setWidth(1024);
                stage.setHeight(768);
                stage.show();

                VBox.setVgrow(browser, Priority.ALWAYS);

                browser.load("http://stackoverflow.com");
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

        public static void main(String[] args) {
            launch(args);
        }
    }
}