SCM-Manager/scm-webapp/src/main/java/sonia/scm/security/DefaultKeyGenerator.java

/**
 * Copyright (c) 2010, Sebastian Sdorra All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer. 2. 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. 3. Neither the name of SCM-Manager;
 * nor the 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 THE REGENTS OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * http://bitbucket.org/sdorra/scm-manager
 *
 */



package sonia.scm.security;

//~--- non-JDK imports --------------------------------------------------------

import com.google.inject.Singleton;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

//~--- JDK imports ------------------------------------------------------------

import java.util.Random;
import java.util.concurrent.atomic.AtomicLong;

/**
 *
 * @author Sebastian Sdorra
 */
@Singleton
public class DefaultKeyGenerator implements KeyGenerator
{

  /** Field description */
  private static final int RANDOM_MAX = 999;

  /** Field description */
  private static final int RANDOM_MIN = 100;

  /**
   * the logger for DefaultKeyGenerator
   */
  private static final Logger logger =
    LoggerFactory.getLogger(DefaultKeyGenerator.class);

  //~--- methods --------------------------------------------------------------

  /**
   * Method description
   *
   *
   * @return
   */
  @Override
  public String createKey()
  {
    StringBuilder buffer = new StringBuilder();

    buffer.append(Long.toHexString(System.currentTimeMillis()));
    buffer.append(Long.toHexString(sessionKey.incrementAndGet()));
    buffer.append(Integer.toHexString(createRandom()));

    String key = buffer.toString();

    if (logger.isTraceEnabled())
    {
      logger.trace("create new key {}", key);
    }

    return key;
  }

  /**
   * Create a random int between {@link #RANDOM_MIN} and {@link #RANDOM_MAX}.
   * This method is package visible for testing.
   *
   * @return a random int between the min and max value
   */
  int createRandom()
  {
    return random.nextInt(RANDOM_MAX - RANDOM_MIN + 1) + RANDOM_MIN;
  }

  //~--- fields ---------------------------------------------------------------

  /** Field description */
  private AtomicLong sessionKey = new AtomicLong();

  /** Field description */
  private Random random = new Random();
}