ClasspathUrlResourceLoader.java

/*
 * Copyright © 2017, Salesforce.com, Inc
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 *
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 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
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 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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package com.salesforce.apt.graph.model.storage.classpath;

import java.io.File;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.List;

import com.salesforce.apt.graph.model.storage.Resource;
import com.salesforce.apt.graph.model.storage.ResourceLoader;

public class ClasspathUrlResourceLoader implements ResourceLoader {

  private ClassLoader classloader;
  
  public ClasspathUrlResourceLoader() {
    classloader = Thread.currentThread().getContextClassLoader();
  }

  public ClasspathUrlResourceLoader(ClassLoader classLoader) {
    classloader = classLoader;
  }

  /**
   * If the file exists, use it a root of the UrlClassLoader.
   * 
   * @param root file system directory to include as part of the classloader.
   */
  public ClasspathUrlResourceLoader(File root) {
    AccessController.doPrivileged(new PrivilegedAction<Void>() {
      public Void run() {
        try {
          classloader = new URLClassLoader(new URL[] {
              root.toURI().toURL()},
              Thread.currentThread().getContextClassLoader());
          return null;
        } catch (MalformedURLException | NullPointerException ex) {
          throw new IllegalArgumentException("Invalide File, it's not a url.", ex);
        }
      }
    });
  }
  
  /**
   * Finds all possible resources that match the name of the DefinitionMode we wish to find.
   * 
   * @param name the resources to search for with in the class loader.
   * @return the list of found resources in class loader.
   */
  public List<Resource> getEntries(String name) {
    List<Resource> output  = new ArrayList<>();
    try {
      Enumeration<URL> resources = classloader.getResources(FileStore.STANDARD.getPath() + "/" 
          + name + ".json");
      while (resources.hasMoreElements()) {
        output.add(new UrlResource(resources.nextElement()));
      }
    } catch (IOException ioe) {
      throw new IllegalStateException("Could not read classpath while looking for ForceInject models of name: " + name, ioe);
    }
    return output;
  }

}