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Content of file JavaFXSafeProxyCreator.java
/* * ********************************************************************************************************************* * * SteelBlue: DCI User Interfaces * http://tidalwave.it/projects/steelblue * * Copyright (C) 2015 - 2023 by Tidalwave s.a.s. (http://tidalwave.it) * * ********************************************************************************************************************* * * 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. * * ********************************************************************************************************************* * * git clone https://bitbucket.org/tidalwave/steelblue-src * git clone https://github.com/tidalwave-it/steelblue-src * * ********************************************************************************************************************* */ package it.tidalwave.ui.javafx; import java.lang.reflect.Proxy; import javax.annotation.Nonnull; import java.util.HashMap; import java.util.Map; import java.util.concurrent.CountDownLatch; import java.util.concurrent.Executor; import java.util.concurrent.TimeUnit; import java.util.concurrent.atomic.AtomicReference; import java.io.IOException; import javafx.fxml.FXMLLoader; import javafx.scene.Node; import javafx.application.Platform; import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor; import it.tidalwave.util.ReflectionUtils; import it.tidalwave.role.ui.javafx.JavaFXBinder; import it.tidalwave.role.ui.javafx.impl.DefaultJavaFXBinder; import it.tidalwave.role.ui.javafx.impl.util.JavaFXSafeProxy; import lombok.Getter; import lombok.RequiredArgsConstructor; import lombok.extern.slf4j.Slf4j; import static lombok.AccessLevel.PRIVATE; /*********************************************************************************************************************** * * This facility class create a thread-safe proxy for the JavaFX delegate (controller). Thread-safe means that it can * be called by any thread and the JavaFX UI related stuff will be safely invoked in the JavaFX UI Thread. * It is usually used in this way: * * <pre> * // This is a Spring bean * public class JavaFxFooBarPresentation implements FooBarPresentation * { * private static final String FXML_URL = "/my/package/javafx/FooBar.fxml"; * * @Inject * private FlowController flowController; * * private final NodeAndDelegate nad = createNodeAndDelegate(getClass(), FXML_URL); * * private final FooBarPresentation delegate = nad.getDelegate(); * * public void showUp() * { * flowController.doSomething(nad.getNode()); * } * * public void showData (final String data) * { * delegate.showData(data); * } * } * </pre> * * The method {@link #createNodeAndDelegate(java.lang.Class, java.lang.String)} safely invokes the {@link FXMLLoader} * and returns a {@link NodeAndDelegate} that contains both the visual {@link Node} and its delegate (controller). * * The latter is wrapped by a safe proxy that makes sure that any method invocation (such as {@code showData()} in the * example is again executed in the JavaFX UI Thread. This means that the Presentation object methods can be invoked * in any thread. * * For method returning {@code void}, the method invocation is asynchronous; that is, the caller is not blocked waiting * for the method execution completion. If a return value is provided, the invocation is synchronous, and the caller * will correctly wait the completion of the execution in order to get the result value. * * A typical JavaFX delegate (controller) looks like: * * <pre> * // This is not a Spring bean - created by the FXMLLoader * public class JavaFxFooBarPresentationDelegate implements FooBarPresentation * { * @FXML * private Label label; * * @FXML * private Button button; * * @Inject // the only thing that can be injected, by means of JavaFXSafeProxyCreator * private JavaFxBinder binder; * * @Override * public void bind (final UserAction action) * { * binder.bind(button, action); * } * * @Override * public void showData (final String data) * { * label.setText(data); * } * } * </pre> * * Not only all the methods invoked on the delegate are guaranteed to run in the JavaFX UI thread, but also its * constructor, as per JavaFX requirements. * * A Presentation Delegate must not try to have dependency injection from Spring (for instance, by means of AOP), * otherwise a deadlock could be triggered. Injection in constructors is safe. * * @author Fabrizio Giudici * **********************************************************************************************************************/ @Slf4j public class JavaFXSafeProxyCreator { private static final String P_TIMEOUT = JavaFXSafeProxyCreator.class.getName() + ".initTimeout"; private static final int initializerTimeout = Integer.getInteger(P_TIMEOUT, 10); public static final Map<Class<?>, Object> BEANS = new HashMap<>(); @Getter private static final ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor(); @Getter private static final JavaFXBinder javaFxBinder = new DefaultJavaFXBinder(executor); static { executor.setWaitForTasksToCompleteOnShutdown(false); executor.setThreadNamePrefix("javafxBinder-"); // Fix for STB-26 executor.setCorePoolSize(1); executor.setMaxPoolSize(1); executor.setQueueCapacity(10000); BEANS.put(JavaFXBinder.class, javaFxBinder); BEANS.put(Executor.class, executor); } private JavaFXSafeProxyCreator () {} /******************************************************************************************************************* * * * ******************************************************************************************************************/ @RequiredArgsConstructor(access = PRIVATE) public static final class NodeAndDelegate {@Getter @Nonnull
Returning a reference to a mutable object value stored in one of the object's fields exposes the internal representation of the object. If instances are accessed by untrusted code, and unchecked changes to the mutable object would compromise security or other important properties, you will need to do something different. Returning a new copy of the object is better approach in many situations.
private final Node node; @Nonnull private final Object delegate; @Nonnull public <T> T getDelegate() { return (T)delegate; } @Nonnull public static <T> NodeAndDelegate load (@Nonnull final Class<T> clazz, @Nonnull final String resource) throws IOException { log.debug("NodeAndDelegate({}, {})", clazz, resource); assert Platform.isFxApplicationThread() : "Not in JavaFX UI Thread"; final var loader = new FXMLLoader(clazz.getResource(resource), null, null, type -> ReflectionUtils.instantiateWithDependencies(type, BEANS)); final Node node = loader.load(); final T jfxController = loader.getController(); ReflectionUtils.injectDependencies(jfxController, BEANS); final var interfaces = jfxController.getClass().getInterfaces(); if (interfaces.length == 0) { log.warn("{} has no interface: not creating safe proxy", jfxController.getClass()); log.debug(">>>> load({}, {}) completed", clazz, resource); return new NodeAndDelegate(node, jfxController); } else { final var interfaceClass = (Class<T>)interfaces[0]; // FIXME final var safeDelegate = JavaFXSafeProxyCreator.createSafeProxy(jfxController, interfaceClass); log.debug(">>>> load({}, {}) completed", clazz, resource); return new NodeAndDelegate(node, safeDelegate); } } } /******************************************************************************************************************* * * Creates a {@link NodeAndDelegate} for the given presentation class. The FXML resource name is inferred by * default, For instance, is the class is named {@code JavaFXFooBarPresentation}, the resource name is * {@code FooBar.fxml} and searched in the same packages as the class. * * @see #createNodeAndDelegate(java.lang.Class, java.lang.String) * * @since 1.0-ALPHA-13 * * @param presentationClass the class of the presentation for which the resources must be created. * ******************************************************************************************************************/ @Nonnull public static <T> NodeAndDelegate createNodeAndDelegate (@Nonnull final Class<?> presentationClass) { final var resource = presentationClass.getSimpleName().replaceAll("^JavaFX", "") .replaceAll("^JavaFx", "") .replaceAll("Presentation$", "") + ".fxml"; return createNodeAndDelegate(presentationClass, resource); } /******************************************************************************************************************* * * Creates a {@link NodeAndDelegate} for the given presentation class. * * @param presentationClass the class of the presentation for which the resources must be created. * @param fxmlResourcePath the path of the FXML resource * ******************************************************************************************************************/ @Nonnull public static <T> NodeAndDelegate createNodeAndDelegate (@Nonnull final Class<?> presentationClass, @Nonnull final String fxmlResourcePath) { log.debug("createNodeAndDelegate({}, {})", presentationClass, fxmlResourcePath); final var latch = new CountDownLatch(1); final var nad = new AtomicReference<NodeAndDelegate>(); final var exception = new AtomicReference<RuntimeException>(); if (Platform.isFxApplicationThread()) { try { return NodeAndDelegate.load(presentationClass, fxmlResourcePath); } catch (IOException e) { exception.set(new RuntimeException(e)); } } Platform.runLater(() -> { try { nad.set(NodeAndDelegate.load(presentationClass, fxmlResourcePath)); } catch (RuntimeException e) { exception.set(e); } catch (Exception e) { exception.set(new RuntimeException(e)); } latch.countDown(); }); try { log.debug("Waiting for NodeAndDelegate initialisation in JavaFX thread..."); log.debug("If deadlocks and you need longer time with the debugger, set {} (current value: {})", P_TIMEOUT, initializerTimeout); latch.await(initializerTimeout, TimeUnit.SECONDS); // FIXME } catch (InterruptedException e) { throw new RuntimeException(e); } if (exception.get() != null) { throw exception.get(); } if (nad.get() == null) { final var message = String.format("Likely deadlock in the JavaFX Thread: couldn't create " + "NodeAndDelegate: %s, %s", presentationClass, fxmlResourcePath); throw new RuntimeException(message); } return nad.get(); } /******************************************************************************************************************* * * * ******************************************************************************************************************/ @Nonnull public static <T> T createSafeProxy (@Nonnull final T target, final Class<T> interfaceClass) { return (T)Proxy.newProxyInstance(Thread.currentThread().getContextClassLoader(), new Class[] { interfaceClass }, new JavaFXSafeProxy<>(target)); } }