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
   *
   *     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.ambari.server.view;
  
  import java.io.IOException;
  import java.net.URL;
  
  import org.apache.ambari.server.view.configuration.ViewConfig;
  import org.eclipse.jetty.webapp.WebAppClassLoader;
  import org.eclipse.jetty.webapp.WebAppContext;
  
  
  /**
   * Class loader used to load classes and resources from a search path of URLs referring to both JAR files
   * and directories.  The URLs will be searched in the order specified for classes and resources before
   * searching the parent class loader.
   */
  public class ViewClassLoader extends WebAppClassLoader {
  
    // ----- Constructors ------------------------------------------------------
  
    /**
     * Constructs a new ViewClassLoader for the given URLs using a default parent class loader.
     * The URLs will be searched in the order specified for classes and resources before searching
     * the parent class loader.
     *
     * @param viewConfig  the view configuration
     * @param urls        the URLs from which to load classes and resources
     */
    public ViewClassLoader(ViewConfig viewConfig, URL[] urls) throws IOException {
      this(viewConfig, null, urls);
    }
  
    /**
     * Constructs a new ViewClassLoader for the given URLs.
     * The URLs will be searched in the order specified for classes and resources before searching the specified
     * parent class loader.
     *
     * @param viewConfig  the view configuration
     * @param parent      the parent class loader
     * @param urls        the URLs from which to load classes and resources
     */
    public ViewClassLoader(ViewConfig viewConfig, ClassLoader parent, URL[] urls) throws IOException {
      super(parent, getInitContext(viewConfig));
  
      for (URL url : urls) {
        addURL(url);
      }
    }
  
  
    // ----- helper methods ----------------------------------------------------
  
    // Get a context to initialize the class loader.
    private static WebAppContext getInitContext(ViewConfig viewConfig) throws IOException {
  
      WebAppContext webAppContext = new WebAppContext();
  
      // add ambari classes as system classes
      webAppContext.getSystemClassMatcher().add("org.apache.ambari.server.");
      webAppContext.getSystemClassMatcher().add("org.apache.ambari.view.");
  
      // add com.google.inject as system classes to allow for injection in view components using the google annotation
      webAppContext.getSystemClassMatcher().add("com.google.inject.");
  
      // add as system classes to avoid conflicts and linkage errors
      webAppContext.getSystemClassMatcher().add("org.slf4j.");
      webAppContext.getSystemClassMatcher().add("com.sun.jersey.");
      webAppContext.getSystemClassMatcher().add("org.apache.velocity.");
  
      // set the class loader settings from the configuration
      if (viewConfig != null) {
        String extraClasspath = viewConfig.getExtraClasspath();
        if (extraClasspath != null) {
          webAppContext.setExtraClasspath(extraClasspath);
        }
      }
      return webAppContext;
    }
  
    @Override
    public Class<?> loadClass(String name) throws ClassNotFoundException {
      System.out.println("Attempting to load class: " + name);
      try {
        // First, try to load the class using the current class loader
        Class<?> loadedClass = super.loadClass(name);
        System.out.println("Class loaded successfully: " + name + " by " + this);
        return loadedClass;
      } catch (ClassNotFoundException e) {
        System.out.println("Class not found in current loader: " + name + ", delegating to parent.");
        // If not found, delegate to the parent class loader
        if (getParent() != null) {
          Class<?> parentLoadedClass = getParent().loadClass(name);
          System.out.println("Class loaded successfully by parent: " + name);
          return parentLoadedClass;
        } else {
          System.out.println("Class not found: " + name + " in both current and parent class loaders.");
          throw e;
        }
      }
    }
  }
  