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/*
 * 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.flink.runtime.util;

import org.apache.flink.util.ExceptionUtils;

import java.io.File;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.jar.JarFile;

/**
 * Utilities for information with respect to class loaders, specifically class loaders for
 * the dynamic loading of user defined classes.
 */
public final class ClassLoaderUtil {

	/**
	 * Gets information about URL class loaders. The returned info string contains all URLs of the
	 * class loader. For file URLs, it contains in addition whether the referenced file exists,
	 * is a valid JAR file, or is a directory.
	 * 
	 * 

NOTE: This method makes a best effort to provide information about the classloader, and * never throws an exception.

* * @param loader The classloader to get the info string for. * @return The classloader information string. */ public static String getUserCodeClassLoaderInfo(ClassLoader loader) { if (loader instanceof URLClassLoader) { URLClassLoader cl = (URLClassLoader) loader; try { StringBuilder bld = new StringBuilder(); if (cl == ClassLoader.getSystemClassLoader()) { bld.append("System ClassLoader: "); } else { bld.append("URL ClassLoader:"); } for (URL url : cl.getURLs()) { bld.append("\n "); if (url == null) { bld.append("(null)"); } else if ("file".equals(url.getProtocol())) { String filePath = url.getPath(); File fileFile = new File(filePath); bld.append("file: '").append(filePath).append('\''); if (fileFile.exists()) { if (fileFile.isDirectory()) { bld.append(" (directory)"); } else { JarFile jar = null; try { jar = new JarFile(filePath); bld.append(" (valid JAR)"); } catch (Exception e) { bld.append(" (invalid JAR: ").append(e.getMessage()).append(')'); } finally { if (jar != null) { jar.close(); } } } } else { bld.append(" (missing)"); } } else { bld.append("url: ").append(url); } } return bld.toString(); } catch (Throwable t) { return "Cannot access classloader info due to an exception.\n" + ExceptionUtils.stringifyException(t); } } else { return "No user code ClassLoader"; } } /** * Checks, whether the class that was not found in the given exception, can be resolved through * the given class loader. * * @param cnfe The ClassNotFoundException that defines the name of the class. * @param cl The class loader to use for the class resolution. * @return True, if the class can be resolved with the given class loader, false if not. */ public static boolean validateClassLoadable(ClassNotFoundException cnfe, ClassLoader cl) { try { String className = cnfe.getMessage(); Class.forName(className, false, cl); return true; } catch (ClassNotFoundException e) { return false; } catch (Exception e) { return false; } } /** * Private constructor to prevent instantiation. */ private ClassLoaderUtil() { throw new RuntimeException(); } }




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