App.java
/*
* Copyright (c) 2010, 2023 Oracle and/or its affiliates. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Distribution License v. 1.0, which is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
package org.glassfish.jersey.examples.reload;
import java.io.BufferedReader;
import java.io.File;
import java.io.IOException;
import java.lang.reflect.Field;
import java.net.URI;
import java.nio.file.Files;
import java.nio.file.FileSystems;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardWatchEventKinds;
import java.nio.file.WatchEvent;
import java.nio.file.WatchKey;
import java.nio.file.WatchService;
import java.util.LinkedList;
import java.util.List;
import java.util.Timer;
import java.util.TimerTask;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.glassfish.jersey.examples.reload.compiler.AppClassLoader;
import org.glassfish.jersey.examples.reload.compiler.Compiler;
import org.glassfish.jersey.examples.reload.compiler.JavaFile;
import org.glassfish.jersey.grizzly2.httpserver.GrizzlyHttpServerFactory;
import org.glassfish.jersey.server.ResourceConfig;
import org.glassfish.jersey.server.spi.Container;
import org.glassfish.jersey.server.spi.ContainerLifecycleListener;
import org.glassfish.grizzly.http.server.HttpServer;
/**
* Reload example application.
* <p/>
* A {@link ContainerLifecycleListener container listener} gets registered
* with the application. Upon application startup notification, the listener schedules
* a new {@link TimerTask timer task} to check a text file called {@code resources}
* every 2 seconds. When the text file change is detected, the application gets reloaded with
* a new {@link ResourceConfig resource configuration} including all
* resource classes listed in that file.
*
* @author Jakub Podlesak
*/
public class App {
private static final Logger LOGGER = Logger.getLogger(App.class.getName());
private static final URI BASE_URI = URI.create("http://localhost:8080/flights/");
public static final String ROOT_PATH = "arrivals";
public static final String CONFIG_FILENAME = "resources";
public static final String SRC_MAIN_JAVA = "src/main/java";
static Container container;
static class FileCheckTask extends TimerTask {
@Override
public void run() {
WatchService watcher;
try {
watcher = FileSystems.getDefault().newWatchService();
Path srcDir = Paths.get("src/main/java/org/glassfish/jersey/examples/reload");
registerWatcher(watcher, srcDir);
Path configFilePath = Paths.get(".");
registerWatcher(watcher, configFilePath);
} catch (IOException e) {
e.printStackTrace();
throw new RuntimeException("Could not initialize watcher service!");
}
for (;;) {
try {
final WatchKey watchKey = watcher.take();
try {
for (WatchEvent<?> event : watchKey.pollEvents()) {
final WatchEvent.Kind<?> kind = event.kind();
if (kind == StandardWatchEventKinds.ENTRY_MODIFY) {
WatchEvent<Path> pathEvent = (WatchEvent<Path>) event;
Path modifiedFile = pathEvent.context();
System.out.printf("FILE MODIFIED: %s\n", modifiedFile);
}
}
} finally {
watchKey.reset(); // so that consecutive events could be processed
}
final File configFile = new File(CONFIG_FILENAME);
reloadApp(configFile);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
}
}
private void registerWatcher(WatchService watcher, Path directory) throws IOException {
directory.register(watcher,
new WatchEvent.Kind[]{
StandardWatchEventKinds.ENTRY_MODIFY
},
/* SensitivityWatchEventModifier.HIGH */ getWatchEventModifiers());
}
private void reloadApp(final File configFile) {
LOGGER.info("Reloading resource classes:");
final ResourceConfig rc = createResourceConfig(configFile);
App.container.reload(rc);
}
/**
* @return sensitivity watch event modifier
*/
private static WatchEvent.Modifier[] getWatchEventModifiers() {
String className = "com.sun.nio.file.SensitivityWatchEventModifier";
try {
Class<?> c = Class.forName(className);
Field f = c.getField("HIGH");
WatchEvent.Modifier modifier = WatchEvent.Modifier.class.cast(f.get(c));
return new WatchEvent.Modifier[] {modifier};
} catch (Exception e) {
return new WatchEvent.Modifier[] {};
}
}
}
private static ResourceConfig createResourceConfig(File configFile) {
final ResourceConfig rc = new ResourceConfig();
try {
final AppClassLoader appClassLoader = new AppClassLoader(Thread.currentThread().getContextClassLoader());
final List<JavaFile> javaFiles = getJavaFiles(configFile);
Compiler.compile(appClassLoader, javaFiles);
for (JavaFile javaFile : javaFiles) {
try {
rc.registerClasses(appClassLoader.loadClass(javaFile.getClassName()));
} catch (final ClassNotFoundException ex) {
LOGGER.info(String.format(" ! class %s not found.\n", javaFile.getClassName()));
}
}
} catch (final Exception ex) {
Logger.getLogger(App.class.getName()).log(Level.SEVERE, null, ex);
}
return rc;
}
private static List<JavaFile> getJavaFiles(File configFile) throws Exception {
final List<JavaFile> javaFiles = new LinkedList<>();
try (BufferedReader r = Files.newBufferedReader(configFile.toPath())) {
while (r.ready()) {
final String className = r.readLine();
if (!className.startsWith("#")) {
javaFiles.add(new JavaFile(className, SRC_MAIN_JAVA));
LOGGER.info(String.format(" + included class %s.\n", className));
} else {
LOGGER.info(String.format(" - ignored class %s\n", className.substring(1)));
}
}
}
return javaFiles;
}
public static void main(final String[] args) throws Exception {
try {
LOGGER.info("Resource Config Reload Jersey Example App");
for (String s : args) {
if (s.startsWith("-cp=")) {
Compiler.classpath = s.substring(4);
}
}
final ResourceConfig resourceConfig = createResourceConfig(new File(CONFIG_FILENAME));
registerReloader(resourceConfig);
final HttpServer server = GrizzlyHttpServerFactory.createHttpServer(BASE_URI, resourceConfig, true);
Runtime.getRuntime().addShutdownHook(new Thread(new Runnable() {
@Override
public void run() {
server.shutdownNow();
}
}));
server.start();
System.out.println(
String.format("Application started.\nTry out %s%s\nStop the application using CTRL+C", BASE_URI, ROOT_PATH));
Thread.currentThread().join();
} catch (IOException | InterruptedException ex) {
Logger.getLogger(App.class.getName()).log(Level.SEVERE, null, ex);
}
}
private static Class<?> loadClass(String className) throws Exception {
final JavaFile javaFile = new JavaFile(className, SRC_MAIN_JAVA);
return Compiler.compile(className, javaFile);
}
private static void registerReloader(ResourceConfig resourceConfig) {
resourceConfig.registerInstances(new ContainerLifecycleListener() {
@Override
public void onStartup(final Container container) {
App.container = container;
final Timer t = new Timer(true);
t.schedule(new FileCheckTask(), 0);
}
@Override
public void onReload(final Container container) {
System.out.println("Application has been reloaded!");
}
@Override
public void onShutdown(final Container container) {
// ignore
}
});
}
}