Finally making some progress on EncycloCrawler – re-crawled Encyclopedia Mythica today. It now shows up in EncycloSearch searches again, and the reader works.
The new version of EncycloSearch is finally live! Check it out @ encyclosearch.org.
I’m almost ready to push the latest version of EncycloSearch, which adds a reader (finally).
Haven’t touched my Minifeed in a while. I think I’ll start using it to post updates on the projects I’m working on.
I’m working on a project which requires a headless browser to parse JavaScript. I’ve tried a few different headless browsers, and none of them managed to parse JavaScript correctly.
Since I couldn’t find a working solution, I had to make it myself. That solution is a wrapper for JavaFX’s WebView. It’s surprisingly short, and I made a basic version of the below code in around 5 minutes:
import java.util.concurrent.CountDownLatch;
import javafx.application.Platform;
import javafx.concurrent.Worker;
import javafx.embed.swing.JFXPanel;
import javafx.scene.web.WebView;
public class HeadlessBrowser {
// Internal WebView, used to load web pages
WebView view;
// Constructor
public HeadlessBrowser() {
new JFXPanel(); // Initializes JavaFX
// Instantiates the WebView. Using Platform.runLate because this has to be done on the JavaFX application thread
runLater(() -> view = new WebView());
}
// Navigates to the given URL.
public void navigate(String url) {
runLater(() -> view.getEngine().load(url));
}
// Used by the getHTML() method.
// This variable can't be in the method because Platform.runLater is used.
String html;
// Gets the HTML of the current page.
public String getHTML() {
// The HTML is retrieved by executing some JavaScript. Once again, this can't be done on the main thread.
runLater(() -> html = (String) view.getEngine().executeScript("document.documentElement.outerHTML"));
// Returns the HTML, which is stored in a variable outside of the method
return html;
}
// Makes the given Runnable run when the page is done loading.
public void navigateAndWait(String url) {
final CountDownLatch doneLatch = new CountDownLatch(1);
runLater(() -> {
view.getEngine().getLoadWorker().stateProperty().addListener((ov, t, t1) -> {
if(t1 == Worker.State.SUCCEEDED) {
doneLatch.countDown();
}
});
});
navigate(url);
try { doneLatch.await(); } catch (InterruptedException e) {}
}
// Stops JavaFX and the headless browser.
// Maybe not the best way to do this, but frees up resources.
public void close() {
Platform.exit();
}
// Platform.runLater, but blocks until the Runnable has been run
private void runLater(Runnable run) {
// queue on JavaFX thread and wait for completion
final CountDownLatch doneLatch = new CountDownLatch(1);
Platform.runLater(() -> {
try {
run.run();
} finally {
doneLatch.countDown();
}
});
try { doneLatch.await(); } catch (InterruptedException e) {}
}
}
Here’s how you can use the class:
public class HeadlessBrowserTest {
public static void main(String[] args) {
HeadlessBrowser browser = new HeadlessBrowser();
browser.navigateAndWait("https://www.example.com");
System.out.println(browser.getHTML());
browser.close();
}
}