abstractexportplugin.java

Java的Web报表库

/**
 * ========================================
 * JFreeReport : a free Java report library
 * ========================================
 *
 * Project Info:  http://www.jfree.org/jfreereport/index.html
 * Project Lead:  Thomas Morgner;
 *
 * (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.
 *
 * ------------------------------
 * AbstractExportPlugin.java
 * ------------------------------
 * (C)opyright 2003, by Thomas Morgner and Contributors.
 *
 * Original Author:  Thomas Morgner;
 * Contributor(s):   David Gilbert (for Simba Management Limited);
 *
 * $Id: AbstractExportPlugin.java,v 1.4.2.2 2003/08/24 14:18:11 taqua Exp $
 *
 * Changes
 * -------------------------
 * 18-Jun-2003 : Initial version
 *
 */

package com.jrefinery.report.preview;

import com.jrefinery.report.util.Worker;

/**
 * The AbstractExportPlugin provides a basic implementation of the ExportPlugin
 * interface.
 *
 * @author Thomas Morgner
 */
public abstract class AbstractExportPlugin implements ExportPlugin
{
  /** The backend to perform post or preprocessing. */
  private PreviewProxyBase base;

  /** The preview proxy used to display the preview component. */
  private PreviewProxy proxy;

  /** The worker instance from the main dialog. */
  private Worker worker;

  /**
   * DefaultConstructor.
   */
  public AbstractExportPlugin()
  {
  }

  /**
   * Returns true if the action is separated, and false otherwise. A separated
   * action starts a new action group and will be spearated from previous actions
   * on the menu and toolbar.
   *
   * @return true, if the action should be separated from previous actions,
   * false otherwise.
   */
  public boolean isSeparated()
  {
    return false;
  }

  /**
   * Returns an error description for the last operation. This implementation
   * provides a basic default failure description text and should be overriden
   * to give a more detailed explaination.
   *
   * @return returns a error description.
   */
  public String getFailureDescription()
  {
    return getDisplayName() + " failed on export.";
  }

  /**
   * Returns true, when this export plugin is used to configure the report or an other
   * plugin.
   *
   * @return true if this is a control plugin, false otherwise.
   */
  public boolean isControlPlugin()
  {
    return false;
  }

  /**
   * Initializes the plugin to work with the given PreviewProxy.
   *
   * @param proxy the preview proxy that created this plugin.
   * @throws NullPointerException if the proxy or the proxy's basecomponent
   * is null.
   */
  public void init(final PreviewProxy proxy)
  {
    if (proxy == null)
    {
      throw new NullPointerException("Proxy must not be null.");
    }
    if (proxy.getBase() == null)
    {
      throw new NullPointerException("Proxy must be initialized.");
    }
    this.base = proxy.getBase();
    this.proxy = proxy;
  }

  /**
   * Returns the preview proxy base. This is the same as
   * calling <code>getProxy().getBase()</code>.
   *
   * @return the preview proxy base.
   */
  public PreviewProxyBase getBase()
  {
    return base;
  }

  /**
   * Returns the preview proxy used to create the export plugin.
   *
   * @return the preview proxy.
   */
  public PreviewProxy getProxy()
  {
    return proxy;
  }

  /**
   * Returns true if the action should be added to the toolbar, and false otherwise.
   *
   * @return true, if the plugin should be added to the toolbar, false otherwise.
   */
  public boolean isAddToToolbar()
  {
    return false;
  }

  /**
   * Updates the status text of the base component.
   *
   * @param text the new status line text.
   */
  protected void updateStatusText(final String text)
  {
    getBase().setStatusText(text);
  }

  /**
   * Provides a default implementation to handle export errors.
   * This implementation updates the status line of the preview component.
   *
   * @param result the result of the export operation.
   * @return the value of result unmodified.
   */
  protected boolean handleExportResult(final boolean result)
  {
    if (isControlPlugin() == false && result == false)
    {
      updateStatusText("Export failed: " + getFailureDescription());
    }
    return result;
  }

  /**
   * Defines the worker instance for that export plugin. Workers can
   * be used to delegate tasks to an other thread. The workers are shared
   * among all export plugins of an dialog instance.
   *
   * @param worker the worker.
   */
  public void defineWorker(Worker worker)
  {
    this.worker = worker;
  }

  /**
   * Delegates the task to a worker. If no worker is defined,
   * the runnable is executed directly.
   *
   * @param runnable the task that should be executed.
   */
  public void delegateTask (Runnable runnable)
  {
    if (worker != null)
    {
      synchronized (worker)
      {
        while (worker.isAvailable() == false)
        {
          try
          {
            worker.wait();
          }
          catch (InterruptedException ie)
          {
            // ignored.
          }
        }
        worker.setWorkload(runnable);
      }
    }
    else
    {
      runnable.run();
    }
  }
}