// package com.sampleapp;

import org.springframework.boot.autoconfigure.SpringBootApplication;

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.web.WebView;
import javafx.stage.Stage;

/**
 * Main Spring-Boot class with JavaFX launcher.
 *
 * @author MartinKoster
 *
 */
@SpringBootApplication
public class SampleApplication {

    public static void main(final String[] args) {
        Application.launch(JavaFxApplication.class, args);
    }

    public static class JavaFxApplication extends Application {

        @Override
        public void start(final Stage primaryStage) {
            final WebView webView = new WebView();
            webView.getEngine().loadContent(
                    "<html><body><img src=\"data:image/gif;base64,R0lGODdhEAAQAMwAAPj7+FmhUYjNfGuxYYDJdYTIeanOpT+DOTuANXi/bGOrWj6CONzv2sPjv2CmV1unU4zPgISg6DJnJ3ImTh8Mtbs00aNP1CZSGy0YqLEn47RgXW8amasW7XWsmmvX2iuXiwAAAAAEAAQAAAFVyAgjmRpnihqGCkpDQPbGkNUOFk6DZqgHCNGg2T4QAQBoIiRSAwBE4VA4FACKgkB5NGReASFZEmxsQ0whPDi9BiACYQAInXhwOUtgCUQoORFCGt/g4QAIQA7\"/></body></html>");
            final Scene scene = new Scene(webView, 100, 100);
            primaryStage.setScene(scene);
            primaryStage.show();
        }
    }
}

build.gradle:

plugins {
    id 'org.springframework.boot' version "2.2.5.RELEASE"
    id 'io.spring.dependency-management' version '1.0.9.RELEASE'
    id 'java'
    id 'maven-publish'
}

 
    apply plugin: 'java'
    apply plugin: 'org.springframework.boot'
    apply plugin: 'io.spring.dependency-management'

    sourceCompatibility = "11"
    targetCompatibility = "11"

bootJar {
         enabled = true
mainClassName = 'com.sampleapp.SampleApplication'
}
      
    repositories {
        mavenLocal()
jcenter()
    }
    

[compileJava, compileTestJava,]*.options*.encoding = 'UTF-8'
    

    dependencies {

        // JAVAFX CROSS PLATFORM DEPENDENCIES
  implementation "org.openjfx:javafx-base:11.0.2:win"
implementation "org.openjfx:javafx-controls:11.0.2:win"
implementation "org.openjfx:javafx-fxml:11.0.2:win"
implementation "org.openjfx:javafx-graphics:11.0.2:win"
implementation "org.openjfx:javafx-media:11.0.2:win"
implementation "org.openjfx:javafx-web:11.0.2:win"
implementation "org.openjfx:javafx-swing:11.0.2:win"

implementation "org.openjfx:javafx-base:11.0.2:linux"
implementation "org.openjfx:javafx-controls:11.0.2:linux"
implementation "org.openjfx:javafx-fxml:11.0.2:linux"
implementation "org.openjfx:javafx-graphics:11.0.2:linux"
implementation "org.openjfx:javafx-media:11.0.2:linux"
implementation "org.openjfx:javafx-web:11.0.2:linux"
implementation "org.openjfx:javafx-swing:11.0.2:linux"
           

        // SPRING BOOT
        implementation("org.springframework.boot:spring-boot-starter-web")
    
    }