001    /*
002     * Sonar, open source software quality management tool.
003     * Copyright (C) 2008-2012 SonarSource
004     * mailto:contact AT sonarsource DOT com
005     *
006     * Sonar is free software; you can redistribute it and/or
007     * modify it under the terms of the GNU Lesser General Public
008     * License as published by the Free Software Foundation; either
009     * version 3 of the License, or (at your option) any later version.
010     *
011     * Sonar is distributed in the hope that it will be useful,
012     * but WITHOUT ANY WARRANTY; without even the implied warranty of
013     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014     * Lesser General Public License for more details.
015     *
016     * You should have received a copy of the GNU Lesser General Public
017     * License along with Sonar; if not, write to the Free Software
018     * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02
019     */
020    package org.sonar.batch.bootstrapper;
021    
022    import java.io.IOException;
023    import java.net.URL;
024    import java.net.URLClassLoader;
025    import java.util.Enumeration;
026    
027    /**
028     * Special {@link URLClassLoader} to execute Sonar, which restricts loading from parent.
029     */
030    public class BootstrapClassLoader extends URLClassLoader {
031    
032      private String[] unmaskedPackages;
033    
034      public BootstrapClassLoader(ClassLoader parent, String... unmaskedPackages) {
035        super(new URL[0], parent);
036        this.unmaskedPackages = unmaskedPackages;
037      }
038    
039      /**
040       * {@inheritDoc} Visibility of a method has been relaxed to public.
041       */
042      @Override
043      public void addURL(URL url) {
044        super.addURL(url);
045      }
046    
047      /**
048       * {@inheritDoc} Visibility of a method has been relaxed to public.
049       */
050      @Override
051      public Class<?> findClass(String name) throws ClassNotFoundException {
052        return super.findClass(name);
053      }
054    
055      /**
056       * @return true, if class can be loaded from parent ClassLoader
057       */
058      boolean canLoadFromParent(String name) {
059        for (String pkg : unmaskedPackages) {
060          if (name.startsWith(pkg + ".")) {
061            return true;
062          }
063        }
064        return false;
065      }
066    
067      /**
068       * Same behavior as in {@link URLClassLoader#loadClass(String, boolean)}, except loading from parent.
069       */
070      @Override
071      protected synchronized Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException {
072        // First, check if the class has already been loaded
073        Class<?> c = findLoadedClass(name);
074        if (c == null) {
075          try {
076            // Load from parent
077            if ((getParent() != null) && canLoadFromParent(name)) {
078              c = getParent().loadClass(name);
079            } else {
080              // Load from system
081              c = getSystemClassLoader().loadClass(name);
082            }
083          } catch (ClassNotFoundException e) {
084            // If still not found, then invoke findClass in order
085            // to find the class.
086            c = findClass(name);
087          }
088        }
089        if (resolve) {
090          resolveClass(c);
091        }
092        return c;
093      }
094    
095      /**
096       * Unlike {@link URLClassLoader#getResource(String)} don't return resource from parent.
097       * See http://jira.codehaus.org/browse/SONAR-2276
098       */
099      @Override
100      public URL getResource(String name) {
101        return findResource(name);
102      }
103    
104      /**
105       * Unlike {@link URLClassLoader#getResources(String)} don't return resources from parent.
106       * See http://jira.codehaus.org/browse/SONAR-2276
107       */
108      @Override
109      public Enumeration<URL> getResources(String name) throws IOException {
110        return findResources(name);
111      }
112    
113    }