Getting HTML input value in JavaFX WebView?

Is it possible to get the value of a HTML input inside a WebView in JavaFX?

If so, how would I use an event so the value updates automatically?

Example App:

package webviewinputvalue;

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.layout.StackPane;
import javafx.scene.web.WebEngine;
import javafx.scene.web.WebView;
import javafx.stage.Stage;

public class WebviewInputValue extends Application {

    @Override
    public void start(Stage primaryStage) {

        WebView test = new WebView();
        WebEngine run = test.getEngine();
        run.loadContent("<textarea></textarea>");
        StackPane root = new StackPane();
        root.getChildren().add(test);

        Scene scene = new Scene(root, 300, 250);

        primaryStage.setTitle("Hello World!");
        primaryStage.setScene(scene);
        primaryStage.show();
    }
      public static void main(String[] args) {
        launch(args);
    }

}

Which creates a simple window like this:

Question: Is it possible to get the value of the textarea using JavaFX? If so, how should I do it?

回答1:

TL;DR: Yes, it's possible, but it requires a bit of a hacky workaround.

First of all, I'm going to move the HTML to it's own separate file, to make editing easier, and just create cleaner code in general.

editor.html

<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8">
        <title>Example Live-view</title>
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
    </head>
    <body>
        <textarea placeholder="Typing 'exit' will kill the program."></textarea>

        <script>
            document.querySelector("textarea").addEventListener("keyup", function(){

                window.status = this.value;
            });
        </script>
    </body>
</html>

The basic structure is really simple, but what about the <script> element? What does it do?

document.querySelector("textarea").addEventListener("keyup", function(){
     window.status = this.value;
});

AFAIK, it isn't possible to straight out get the value of an input in JavaFX, so you have to make a workaround. In this case, I'm setting the window status with the textarea value, whenever there is a keyup event in the textarea.

Now we need to set up the webview in our JavaFX.

WebviewInputValue.java

package webviewinputvalue;

public class WebviewInputValue extends Application {

    private WebView InitWebview(){

        //Create browser
        WebView browser = new WebView();
        WebEngine render = browser.getEngine();

        //Load simple HTML
        String editor = WebviewInputValue.class.getResource("editor.html").toExternalForm();
        render.load(editor);

        //Listen for state change
        render.getLoadWorker().stateProperty().addListener((ov, o, n) -> {
            if (Worker.State.SUCCEEDED == n) {
                render.setOnStatusChanged(webEvent -> {

                    //Call value change
                    onValueChange(webEvent.getData());
                });
            }
        });

        return browser;
    }

    //called when value changes
    private void onValueChange(String data){

        //Print out data
        System.out.println(data);

        //If the data is equal to "exit", close the program
        if("exit".equals(data)){

            //Print goodbye message
            System.out.println("Received exit command! Goodbye :D");

            //Exit
            System.exit(0);
        }
    }

    @Override
    public void start(Stage primaryStage) {

        //Create browser
        WebView browser = InitWebview();

        StackPane root = new StackPane();
        root.getChildren().add(browser);

        Scene scene = new Scene(root, 300, 250);

        primaryStage.setTitle("Hello World!");
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        launch(args);
    }
}

Again, very simple code. Let's dig into it:

private WebView InitWebview(){

    //Create browser
    WebView browser = new WebView();
    WebEngine render = browser.getEngine();

    //Load simple HTML
    String editor = WebviewInputValue.class.getResource("editor.html").toExternalForm();
    render.load(editor);

    //Listen for state change
    render.getLoadWorker().stateProperty().addListener((ov, o, n) -> {
        if (Worker.State.SUCCEEDED == n) {
            render.setOnStatusChanged(webEvent -> {

                //Call value change
                onValueChange(webEvent.getData());
            });
        }
    });

    return browser;
}

First we create the webview and engine, then load the editor.html file into the webview. Next, we fetch the loadWorker, which is what controls the window.status object we are writing to with the JS. We then get the state property, and add an listener. If the listener is added successfully, then listen for a change event.

When the change event, we'll call our onValueChange method:

//called when value changes
private void onValueChange(String data){

    //Print out data
    System.out.println(data);

    //If the data is equal to "exit", close the program
    if("exit".equals(data)){

        //Print goodbye message
        System.out.println("Received exit command! Goodbye :D");

        //Exit
        System.exit(0);
    }
}

This is extremely simple. onValueChange is called with the textarea value as the data parameter. In this case, I'm printing it to the console. If I type exit into the textarea, then it will print a goodbye message and close the application.

And that's it! If you run the above code, then it'll log the textarea value into the console real-time!

Note:

Your project structure should look this, with editor in the same dir as the java file, if you want this code to work straight off:

Also, I'm obviously missing the imports in the java code.

回答2:

3 years later, but I hope it will help someone. I found how to get text from TextArea without changing html page

Runnable check = () -> {            
    WebEngine engine = webView.getEngine();
    if (engine != null) {
        Document document = engine.getDocument();
        if (document != null) {
            Element element = document.getElementById("samlResponse");
            if (element instanceof HTMLTextAreaElement) {
                HTMLTextAreaElement textArea = (HTMLTextAreaElement) element;
                String text = textArea.getValue();
                if (text != null && !text.isEmpty()) {
                    System.out.println("BINGO:\n" + text);
                    System.exit(0);
                }
            }
        }
    }
};

new Thread(() -> {
    while (true) {
        Platform.runLater(check);

        try {
            Thread.sleep(1_000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}).start();