cvs commit: xml-cocoon2/src/org/apache/cocoon/servlet ParanoidClassLoader.java

[bl...@apache.org]

bloritsch    01/05/23 07:05:04

  Added:       src/org/apache/cocoon/servlet ParanoidClassLoader.java
  Log:
  Add new classloader to reverse the order of classloading.  Hopefully this will
  sufficiently isolate Cocoon from the parent classloaders while still allowing for
  using the Servlet Engine's other jars.
  
  Revision  Changes    Path
  1.1                  xml-cocoon2/src/org/apache/cocoon/servlet/ParanoidClassLoader.java
  
  Index: ParanoidClassLoader.java
  ===================================================================
  /*****************************************************************************
   * Copyright (C) The Apache Software Foundation. All rights reserved.        *
   * ------------------------------------------------------------------------- *
   * This software is published under the terms of the Apache Software License *
   * version 1.1, a copy of which has been included  with this distribution in *
   * the LICENSE file.                                                         *
   *****************************************************************************/
  package org.apache.cocoon.servlet;
  
  import java.net.URL;
  import java.net.URLClassLoader;
  import java.net.URLStreamHandlerFactory;
  
  /**
   * The <code>ParanoidClassLoader</code> reverses the search order for
   * classes.  It checks this classloader before it checks its parent.
   *
   * @author <a href="mailto:bloritsch@apache.org">Berin Loritsch</a>
   * @version CVS $Revision: 1.1 $ $Date: 2001/05/23 14:05:01 $
   */
  
  public class ParanoidClassLoader extends URLClassLoader {
      /**
       * The parent <code>ClassLoader</code>.
       */
      private final ClassLoader parent;
  
      /**
       * Default constructor has no parents or initial <code>URL</code>s.
       */
      public ParanoidClassLoader() {
          this(null, null, null);
      }
  
      /**
       * Alternate constructor to define a parent.
       */
      public ParanoidClassLoader(final ClassLoader parent) {
          this(null, parent, null);
      }
  
      /**
       * Alternate constructor to define initial <code>URL</code>s.
       */
      public ParanoidClassLoader(final URL[] urls) {
          this(urls, null, null);
      }
  
      /**
       * Alternate constructor to define a parent and initial
       * <code>URL</code>s.
       */
      public ParanoidClassLoader(final URL[] urls, final ClassLoader parent) {
          this(urls, parent, null);
      }
  
      /**
       * Alternate constructor to define a parent, initial
       * <code>URL</code>s, and a default
       * <code>URLStreamHandlerFactory</code>.
       */
      public ParanoidClassLoader(final URL[] urls, final ClassLoader parent, final URLStreamHandlerFactory factory) {
          super(urls, null, factory);
          this.parent = parent;
      }
  
      /**
       * Extends <code>URLClassLoader</code>'s initialization methods so
       * we return a <code>ParanoidClassLoad</code> instead.
       */
      public static final URLClassLoader newInstance(final URL[] urls) {
          return new ParanoidClassLoader(urls);
      }
  
      /**
       * Extends <code>URLClassLoader</code>'s initialization methods so
       * we return a <code>ParanoidClassLoad</code> instead.
       */
      public static final URLClassLoader newInstance(final URL[] urls, final ClassLoader parent) {
          return new ParanoidClassLoader(urls, parent);
      }
  
      /**
       * Loads the class from this <code>ClassLoader</class>.  If the
       * class does not exist in this one, we check the parent.  Please
       * note that this is the exact opposite of the
       * <code>ClassLoader</code> spec.  We use it to work around
       * inconsistent class loaders from third party vendors.
       */
      public final Class loadClass(final String name) throws ClassNotFoundException {
          Class resource = null;
  
          try {
              resource = super.loadClass(name);
          } catch (ClassNotFoundException t) {
              if (this.parent != null) {
                  this.parent.loadClass(name);
              } else {
                  throw t;
              }
          }
  
          return resource;
      }
  
      /**
       * Gets a resource from this <code>ClassLoader</class>.  If the
       * resource does not exist in this one, we check the parent.
       * Please note that this is the exact opposite of the
       * <code>ClassLoader</code> spec.  We use it to work around
       * inconsistent class loaders from third party vendors.
       */
      public final URL getResource(final String name) {
          URL resource = super.getResource(name);
  
          if (this.parent != null && resource == null) {
              resource = this.parent.getResource(name);
          }
  
          return resource;
      }
  }
  
  
  

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