com.phloc.schematron.xslt.SchematronResourceXSLTCache Maven / Gradle / Ivy

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Library for validating XML documents with Schematron
There is a newer version: 2.7.1
/**
 * Copyright (C) 2014 phloc systems
 * http://www.phloc.com
 * office[at]phloc[dot]com
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.phloc.schematron.xslt;

import java.util.HashMap;
import java.util.Locale;
import java.util.Map;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import javax.annotation.concurrent.ThreadSafe;

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

import com.phloc.commons.GlobalDebug;
import com.phloc.commons.ValueEnforcer;
import com.phloc.commons.error.IResourceError;
import com.phloc.commons.io.IReadableResource;
import com.phloc.commons.xml.transform.CollectingTransformErrorListener;
import com.phloc.commons.xml.transform.LoggingTransformErrorListener;

/**
 * Factory for creating {@link ISchematronXSLTProvider} objects.
 *
 * @author PEPPOL.AT, BRZ, Philip Helger
 */
@ThreadSafe
public final class SchematronResourceXSLTCache
{
  private static final Logger s_aLogger = LoggerFactory.getLogger (SchematronResourceXSLTCache.class);
  private static final Lock s_aLock = new ReentrantLock ();
  private static final Map  s_aCache = new HashMap  ();

  private SchematronResourceXSLTCache ()
  {}

  @Nullable
  public static ISchematronXSLTProvider createSchematronXSLTProvider (@Nonnull final IReadableResource aXSLTResource)
  {
    if (GlobalDebug.isDebugMode () && s_aLogger.isInfoEnabled ())
      s_aLogger.info ("Compiling XSLT instance " + aXSLTResource.toString ());

    final CollectingTransformErrorListener aCEH = new CollectingTransformErrorListener (GlobalDebug.isDebugMode () ? new LoggingTransformErrorListener (Locale.US)
                                                                                                                  : null);
    final SchematronProviderXSLTPrebuild aXSLTPreprocessor = new SchematronProviderXSLTPrebuild (aXSLTResource, aCEH);
    if (!aXSLTPreprocessor.isValidSchematron ())
    {
      // Schematron is invalid -> parsing failed
      s_aLogger.warn ("The XSLT resource '" + aXSLTResource.getResourceID () + "' is invalid!");
      for (final IResourceError aError : aCEH.getResourceErrors ())
        s_aLogger.warn ("  " + aError.getAsString (Locale.US));
      return null;
    }

    // If it is a valid schematron, there must be a result XSLT present!
    if (aXSLTPreprocessor.getXSLTDocument () == null)
    {
      // Note: this should never occur, as it is in the Prebuild implementation
      // the same as "isValidSchematron" but to be implementation agnostic, we
      // leave the check anyway.
      throw new IllegalStateException ("No XSLT document retrieved from XSLT resource '" +
                                       aXSLTResource.getResourceID () +
                                       "'!");
    }

    // Create the main validator for the schematron
    return aXSLTPreprocessor;
  }

  /**
   * Create a new Schematron validator for the passed resource.
   *
   * @param aXSLTResource
   *        The resource of the Schematron rules. May not be null.
   * @return null if the passed Schematron resource does not exist.
   */
  @Nullable
  public static ISchematronXSLTProvider getSchematronXSLTProvider (@Nonnull final IReadableResource aXSLTResource)
  {
    ValueEnforcer.notNull (aXSLTResource, "resource");

    if (!aXSLTResource.exists ())
    {
      s_aLogger.warn ("XSLT resource " + aXSLTResource + " does not exist!");
      return null;
    }

    s_aLock.lock ();
    try
    {
      // Determine the unique resource ID for caching
      final String sResourceID = aXSLTResource.getResourceID ();

      // Validator already in the cache?
      ISchematronXSLTProvider aProvider = s_aCache.get (sResourceID);
      if (aProvider == null)
      {
        // Create new object and put in cache
        aProvider = createSchematronXSLTProvider (aXSLTResource);
        if (aProvider != null)
          s_aCache.put (sResourceID, aProvider);
      }
      return aProvider;
    }
    finally
    {
      s_aLock.unlock ();
    }
  }
}