systemclock.java

一个完整的XACML工程,学习XACML技术的好例子!

/*
* Copyright (c) 2000-2005, University of Salford
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without 
* modification, are permitted provided that the following conditions are met:
*
* 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. 
*
* Neither the name of the University of Salford 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 COPYRIGHT OWNER 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 
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
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*/

package issrg.pba.rbac;

import java.util.Calendar;

/**
 * This class is the simplest implementation of the Clock interface and returns 
 * just system time
 * to the caller. Note that this might not be secure enough for certain 
 * applications.
 */
public class SystemClock extends Clock{
  private java.util.Date lastTime = null;

  public SystemClock() {}

  /**
   * This method returns the time that was at the last call to latch() method.
   * If latch() wasn't called at all, it is called at this time.
   */
  public java.util.Date getTime(){
    return (lastTime==null)? latch(): lastTime;
  }

  /**
   * Sets the time for the next calls to getTime and returns the current system time.
   *
   * @return the time as set on the local conputer
   */
  public java.util.Date latch(){
    return lastTime = new java.util.GregorianCalendar().getTime();
  }
}