content: /*****************************************************************
   *   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
   *
   *    https://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.cayenne.modeler;
  
  import java.io.File;
  import java.net.MalformedURLException;
  import java.net.URL;
  import java.net.URLClassLoader;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.List;
  
  /**
   * A default implementation of ClassLoadingService used in CayenneModeler.
   * 
   * @since 1.1
   */
  public class FileClassLoadingService implements ClassLoadingService {
  
      private FileClassLoader classLoader;
      private List<File> pathFiles;
  
      public FileClassLoadingService() {
          this.pathFiles = new ArrayList<>(15);
      }
  
      /**
       * Returns class for a given name, loading it if needed from configured
       * locations.
       */
      @SuppressWarnings("unchecked")
      public <T> Class<T> loadClass(Class<T> interfaceType, String className) throws ClassNotFoundException {
          return (Class<T>) nonNullClassLoader().loadClass(className);
      }
  
      /**
       * Returns a ClassLoader based on the current configured CLASSPATH settings.
       */
      public ClassLoader getClassLoader() {
          return nonNullClassLoader();
      }
  
      /**
       * Returns an unmodifiable list of configured CLASSPATH locations.
       */
      public List<File> getPathFiles() {
          return Collections.unmodifiableList(pathFiles);
      }
  
      public void setPathFiles(Collection<File> files) {
  
          pathFiles.clear();
          classLoader = null;
  
          for (File file : files) {
              addFile(file);
          }
      }
  
      /**
       * Adds a new location to the list of configured locations.
       */
      private void addFile(File file) {
          file = file.getAbsoluteFile();
  
          if (pathFiles.contains(file)) {
              return;
          }
  
          if (classLoader != null) {
              try {
                  classLoader.addURL(file.toURI().toURL());
              } catch (MalformedURLException ex) {
                  return;
              }
          }
  
          pathFiles.add(file);
      }
  
      private FileClassLoader nonNullClassLoader() {
          // init class loader on demand
          if (classLoader == null) {
              classLoader = new FileClassLoader(getClass().getClassLoader(), pathFiles);
          }
  
          return classLoader;
      }
  
      // URLClassLoader with addURL method exposed.
      private static class FileClassLoader extends URLClassLoader {
  
          FileClassLoader(ClassLoader parent) {
              super(new URL[0], parent);
          }
  
          FileClassLoader(ClassLoader parent, List<File> files) {
              this(parent);
  
              for (File file : files) {
                  // I guess here we have to quetly ignore invalid URLs...
                  try {
                      addURL(file.toURI().toURL());
                  } catch (MalformedURLException ignored) {
                  }
              }
          }
  
          public void addURL(URL url) {
              super.addURL(url);
          }
      }
  }
  