ExpansionDirectory.java

/**********************************************************************
 * Copyright (c) 2005-2009 ant4eclipse project team.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     Nils Hartmann, Daniel Kasmeroglu, Gerd Wuetherich, Christoph Läubrich
 **********************************************************************/
package org.ant4eclipse.lib.pde.internal.tools;

import java.io.File;
import java.util.UUID;

import org.ant4eclipse.lib.core.util.Utilities;

/**
 * <p>
 * Helper class to fetch the expansion directory. The expansion directory is used to extract files from bundles or
 * features during the runtime of ant4eclipse.
 * </p>
 * 
 * @author Gerd Wütherich (gerd@gerd-wuetherich.de)
 */
public class ExpansionDirectory {

  /** the default expansion directory **/
  public static final String DEFAULT_EXPANSION_DIRECTORY                           = System
                                                                                       .getProperty("java.io.tmpdir")
                                                                                       + File.separatorChar
                                                                                       + "a4e_expand_dir_"
                                                                                       + UUID.randomUUID();

  /** the name of the expansion directory property **/
  public static final String EXPANSION_DIRECTORY_PROPERTY_NAME                     = "a4e.expansion.directory";

  /** skip removal of expansion dir when ant4eclipse ends */
  public static final String EXPANSION_DIRECTORY_DONOTREMOVE_ON_EXIT_PROPERTY_NAME = "a4e.expansion.directory.do-not-remove-on-exit";

  /** the expansion directory */
  private static File        expansionDir                                          = null;

  /**
   * <p>
   * Returns the expansion directory.
   * </p>
   * 
   * @return the expansion directory.
   */
  public static synchronized File getExpansionDir() {

    // if the expansion directory is not set, create it...
    if (expansionDir == null) {

      // get the directory name
      String expansionDirectory = System.getProperty(ExpansionDirectory.EXPANSION_DIRECTORY_PROPERTY_NAME,
          ExpansionDirectory.DEFAULT_EXPANSION_DIRECTORY);

      // create the directory
      expansionDir = new File(expansionDirectory);

      // delete expansion directory if is exists. This is necessary to prevent invalid bundle content if
      // the same version number is used in several builds
      if (expansionDir.exists()) {
        Utilities.delete(expansionDir);
      }

      // create if not exists
      if (!expansionDir.exists()) {
        boolean created = expansionDir.mkdirs();
        if (!created) {
          throw new RuntimeException("can't create expansion directory " + expansionDirectory);
        }
      }

      if (!Boolean.getBoolean(EXPANSION_DIRECTORY_DONOTREMOVE_ON_EXIT_PROPERTY_NAME)) {
        // delete on exit
        Runtime.getRuntime().addShutdownHook(new Thread(new Runnable() {

          public void run() {
            if (expansionDir.exists()) {
              Utilities.delete(expansionDir);
            }
          }
        }));
      }
    }

    // return the expansion directory
    return expansionDir;
  }
}