Github user trkurc commented on a diff in the pull request: https://github.com/apache/nifi/pull/271#discussion_r56104556 --- Diff: nifi-nar-bundles/nifi-spring-bundle/nifi-spring-processors/src/main/java/org/apache/nifi/spring/SpringContextFactory.java --- @@ -0,0 +1,139 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You 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. + */ +package org.apache.nifi.spring; + +import java.io.File; +import java.io.InputStream; +import java.lang.reflect.Constructor; +import java.net.URL; +import java.net.URLClassLoader; +import java.util.ArrayList; +import java.util.Arrays; +import java.util.List; + +import org.apache.commons.io.IOUtils; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +/** + * Helper class which provides factory method to create and initialize Spring + * Application Context while scoping it within the dedicated Class Loader. + */ +final class SpringContextFactory { + + private static final Logger logger = LoggerFactory.getLogger(SpringContextFactory.class); + + private static final String SC_DELEGATE_NAME = "org.apache.nifi.spring.bootstrap.SpringContextDelegate"; + + /** + * Creates and instance of Spring Application Context scoped within a + * dedicated Class Loader + */ + static SpringDataExchanger createSpringContextDelegate(String classpath, String config) { + System.out.println(SpringContextFactory.class.getClassLoader()); + URL[] urls = gatherAdditionalClassPathUrls(classpath); + SpringContextClassLoader contextCl = new SpringContextClassLoader(urls, + SpringContextFactory.class.getClassLoader()); + try { + InputStream delegateStream = contextCl.getResourceAsStream(SC_DELEGATE_NAME.replace('.', '/') + ".class"); + byte[] delegateBytes = IOUtils.toByteArray(delegateStream); + Class<?> clazz = contextCl.doDefineClass(SC_DELEGATE_NAME, delegateBytes, 0, delegateBytes.length); + Constructor<?> ctr = clazz.getDeclaredConstructor(String.class); + ctr.setAccessible(true); + SpringDataExchanger springDelegate = (SpringDataExchanger) ctr.newInstance(config); + if (logger.isInfoEnabled()) { + logger.info("Successfully instantiated Spring Application Context from '" + config + "'"); + } + return springDelegate; + } catch (Exception e) { + try { + contextCl.close(); + } catch (Exception e2) { + // ignore + } + throw new IllegalStateException("Failed to instantiate Spring Application Context. Config path: '" + config + + "'; Classpath: " + Arrays.asList(urls), e); + } + } + + /** + * + */ + private static URL[] gatherAdditionalClassPathUrls(String path) { + if (logger.isDebugEnabled()) { + logger.debug("Adding additional resources from '" + path + "' to the classpath."); + } + File libraryDir = new File(path); + if (libraryDir.exists() && libraryDir.isDirectory()) { + String[] cpResourceNames = libraryDir.list(); + try { + URLClassLoader thisCl = (URLClassLoader) SpringContextFactory.class.getClassLoader(); + List<URL> urls = new ArrayList<>(); + for (int i = 0; i < cpResourceNames.length; i++) { + if (!isDuplicate(thisCl.getURLs(), cpResourceNames[i])) { + URL url = new File(libraryDir, cpResourceNames[i]).toURI().toURL(); + urls.add(url); + if (logger.isDebugEnabled()) { + logger.debug("Identifying additional resource to the classpath: " + url); + } + } + } + return urls.toArray(new URL[] {}); + } catch (Exception e) { + throw new IllegalStateException( + "Failed to parse user libraries from '" + libraryDir.getAbsolutePath() + "'", e); + } + } else { + throw new IllegalArgumentException("Path '" + libraryDir.getAbsolutePath() + + "' is not valid because it doesn't exist or does not point to a directory."); + } + } + + /** + * + */ + static boolean isDuplicate(URL[] currentURLs, String resourceName) { + if (resourceName.startsWith("spring")) { + resourceName = resourceName.substring(0, resourceName.lastIndexOf("-")); --- End diff -- not sure I read the code flow correct, but if I have a jar in my application class path named springtony.jar, will this blow up?
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