boot.java

swing编写的库存管理程序。毕业设计类

/**
 * ========================================
 * JFreeReport : a free Java report library
 * ========================================
 *
 * Project Info:  http://www.jfree.org/jfreereport/index.html
 * Project Lead:  Thomas Morgner ([e-mail]);
 *
 * (C) Copyright 2000-2003, by Simba Management Limited and Contributors.
 *
 * This library is free software; you can redistribute it and/or modify it under the terms
 * of the GNU Lesser General Public License as published by the Free Software Foundation;
 * either version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
 * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License along with this
 * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
 * Boston, MA 02111-1307, USA.
 *
 * ------------------------------
 * Boot.java
 * ------------------------------
 * (C)opyright 2003, by Thomas Morgner and Contributors.
 *
 * Original Author:  Thomas Morgner;
 * Contributor(s):   David Gilbert (for Simba Management Limited);
 *
 * $Id: Boot.java,v 1.6 2003/11/23 16:50:45 taqua Exp $
 *
 * Changes 
 * -------------------------
 * 01-Sep-2003 : Initial version
 *  
 */

package org.jfree.report;

import org.jfree.report.modules.PackageManager;
import org.jfree.report.util.CSVTokenizer;
import org.jfree.report.util.Log;

/**
 * An utility class to safely boot and initialize the JFreeReport library.
 * This class should be called before using the JFreeReport classes, to
 * make sure that all subsystems are initialized correctly and in the correct
 * order.
 * <p>
 * Application developers should make sure, that the booting is done, before
 * JFreeReport objects are used. Although the boot process will be started
 * automaticly if needed, this automated start may no longer guarantee the 
 * module initialization order.  
 * <p>
 * Additional modules can be specified by defining the system property
 * "org.jfree.report.boot.Modules". The property expects a comma-separated
 * list of Module implementations.
 * 
 * @author Thomas Morgner
 */
public final class Boot
{
  /** A flag indicating whether the booting is currenly in progress. */ 
  private static boolean bootInProgress;
  /** A flag indicating whether the booting is complete. */
  private static boolean bootDone;

  /**
   * Hidden default constructor.
   */
  private Boot ()
  {
  }
  
  /**
   * Checks, whether the booting of JFreeReport is in progress.
   * 
   * @return true, if the booting is in progress, false otherwise.
   */
  public static boolean isBootInProgress()
  {
    return bootInProgress;
  }

  /**
   * Checks, whether the booting of JFreeReport is complete.
   * 
   * @return true, if the booting is complete, false otherwise.
   */
  public static boolean isBootDone()
  {
    return bootDone;
  }

  /**
   * Starts the boot process. This method does nothing, if the booting
   * is currently in progress or already done.
   */
  public static void start()
  {
    if (isBootInProgress() || isBootDone())
    {
      return;
    }
    bootInProgress = true;

    final JFreeReportInfo info = new JFreeReportInfo();
    Log.info (info.getName() + " " + info.getVersion());

    if (isStrictFP() == false)
    {
      Log.warn ("The used VM seems to use a non-strict floating point arithmetics");
      Log.warn ("Layouts computed with this Java Virtual Maschine may be invalid.");
      Log.warn ("JFreeReport and the library 'iText' depend on the strict floating point rules");
      Log.warn ("of Java1.1 as implemented by the Sun Virtual Maschines.");
      Log.warn ("If you are using the BEA JRockit VM, start the Java VM with the option");
      Log.warn ("'-Xstrictfp' to restore the default behaviour."); 
    }

    final PackageManager mgr = PackageManager.getInstance();

    mgr.addModule(JFreeReportCoreModule.class.getName());
    mgr.addModule(DefaultLogModule.class.getName());
    mgr.load("org.jfree.report.modules.");
    mgr.load("org.jfree.report.ext.modules.");
    try
    {
      final String bootModules = System.getProperty("org.jfree.report.boot.Modules");
      if (bootModules != null)
      {
        final CSVTokenizer csvToken = new CSVTokenizer(bootModules, ",");
        while (csvToken.hasMoreTokens())
        {
          final String token = csvToken.nextToken();
          mgr.load(token);
        }
      }
    }
    catch (SecurityException se)
    {
      Log.info ("Security settings forbid to check the system properties for extension modules.");
    }
    catch (Exception se)
    {
      Log.error 
        ("An error occured while checking the system properties for extension modules.", se);
    }

    mgr.initializeModules();
    bootDone = true;
  }

  /**
   * This method returns true on non-strict floating point systems.
   * <p>
   * Since Java1.2 VMs may implement the floating point arithmetics
   * in a more performant way, which does not put the old strict constraints
   * on the floating point types <code>float</code> and <code>double</code>
   * <p>
   * As iText and this library requires strict (in the sense of Java1.1)
   * floating point operations, we have to test for that feature here.
   * <p>
   * The only known VM that seems to implement that feature is the
   * JRockit VM. The strict mode can be restored on that VM by adding
   * the "-Xstrictfp" VM parameter.
   *
   * @return true, if the VM uses strict floating points by default,
   * false otherwise.
   */
  public static boolean isStrictFP ()
  {
    final double d = 8e+307;
    final double result1 = 4.0 * d * 0.5;
    final double result2 = 2.0 * d;
    return (result1 != result2 && (result1 == Double.POSITIVE_INFINITY));
  }
}