cvs commit: jakarta-velocity/src/java/org/apache/velocity/runtime CachedTemplate.java

[da...@locus.apache.org]

daveb       00/08/30 06:04:27

  Added:       src/java/org/apache/velocity/runtime CachedTemplate.java
  Log:
  Intial add.
  
  Revision  Changes    Path
  1.1                  jakarta-velocity/src/java/org/apache/velocity/runtime/CachedTemplate.java
  
  Index: CachedTemplate.java
  ===================================================================
  package org.apache.velocity.runtime;
  
  /*
   * The Apache Software License, Version 1.1
   *
   * Copyright (c) 2000 The Apache Software Foundation.  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. The end-user documentation included with the redistribution, if
   *    any, must include the following acknowlegement:
   *       "This product includes software developed by the
   *        Apache Software Foundation (http://www.apache.org/)."
   *    Alternately, this acknowlegement may appear in the software itself,
   *    if and wherever such third-party acknowlegements normally appear.
   *
   * 4. The names "The Jakarta Project", "Tomcat", and "Apache Software
   *    Foundation" must not be used to endorse or promote products derived
   *    from this software without prior written permission. For written
   *    permission, please contact apache@apache.org.
   *
   * 5. Products derived from this software may not be called "Apache"
   *    nor may "Apache" appear in their names without prior written
   *    permission of the Apache Group.
   *
   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED 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 APACHE SOFTWARE FOUNDATION OR
   * ITS 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.
   * ====================================================================
   *
   * This software consists of voluntary contributions made by many
   * individuals on behalf of the Apache Software Foundation.  For more
   * information on the Apache Software Foundation, please see
   * <http://www.apache.org/>.
   */
  
  import java.io.*;
  
  import org.apache.velocity.*;
  
  /**
   * This class is used to wrap a pre-parsed template.
   * It also contains additional logic to help reduce
   * disk I/O while at the same time allowing updates to 
   * templates if desired.
   * 
   * @author Dave Bryson
   * $Revision: 1.1 $
   */
  public class CachedTemplate
  {
      private Template template = null;
      private File file = null;
      private long lastmodified = 0;
      private long checkInterval= 0;
      private long lastcheck = 0;
      private long nextcheck = 0;
      
      /**
       * Constructor
       * @param the template file
       */
      public CachedTemplate( File file )
      {
          this.file=file;
      }
      
      /**
       * Check to see if the template is still valid
       * according to our rules.
       * @return true or false
       */
      public boolean isValid() throws IOException
      {
          // If the file is null, no need
          // to continue. We'll load it again
          if ( file == null )
          {
              return false;
          }
          
          // If the time interval that we defined
          // in the props file has expired, then we need 
          // to do some additional checks on the file.
          if ( lastcheck >= nextcheck )
          {
              // Does the file still exist?
              // if not, no need to continue.
              if ( !file.exists() )
              {
                  return false;
              }
             
              // Check to see if the file has been modified since
              // we last cached it.
              if ( lastmodified != file.lastModified() )
              {
                  // reload since it has changed on disk.
                  reload();
              }
          }
          else
          {
              // update the last check time.
              lastcheck=System.currentTimeMillis(); 
          }
          
          return true;
      }
      
      /**
       * @return the time interval to 
       * check the file.
       */
      public long getInterval()
      {
          return checkInterval;
      }
  
      /**
       * Set the time interval
       * @param the interval
       */
      public void setInterval( long intrval )
      {
          this.checkInterval=intrval;
      }
  
      /**
       * Set the file
       * @param the file for the template
       */
      public void setFile( File f )
      {
          this.file=file;
      }
  
      /**
       * Return the pre-parsed template
       * @return template 
       */
      public Template getTemplate()
      {
          return template;
      }
      
      /**
       * Set the template
       * @param the template
       */
      public void setTemplate( Template t)
      {
          this.template=t;
      }
      
      /**
       * Reload the file from disk.
       */
      private void reload()
      {
          if ( file.canRead() )
          {
              template = new Template( file.getAbsolutePath() );
              template.preParse();
              lastcheck=System.currentTimeMillis();
              nextcheck= lastcheck+checkInterval;
          }
          
      }
  }