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	git-svn-id: https://svn.alfresco.com/repos/alfresco-enterprise/alfresco/HEAD/root@18931 c4b6b30b-aa2e-2d43-bbcb-ca4b014f7261
		
			
				
	
	
		
			303 lines
		
	
	
		
			13 KiB
		
	
	
	
		
			Java
		
	
	
	
	
	
			
		
		
	
	
			303 lines
		
	
	
		
			13 KiB
		
	
	
	
		
			Java
		
	
	
	
	
	
| /*
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|  * Copyright (C) 2005 Jesper Steen Møller
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|  *
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|  * This file is part of Alfresco
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|  *
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|  * Alfresco is free software: you can redistribute it and/or modify
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|  * it under the terms of the GNU Lesser General Public License as published by
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|  * the Free Software Foundation, either version 3 of the License, or
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|  * (at your option) any later version.
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|  *
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|  * Alfresco is distributed in the hope that it will be useful,
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|  * but WITHOUT ANY WARRANTY; without even the implied warranty of
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|  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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|  * GNU Lesser General Public License for more details.
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|  *
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|  * You should have received a copy of the GNU Lesser General Public License
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|  * along with Alfresco. If not, see <http://www.gnu.org/licenses/>.
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|  */
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| package org.alfresco.repo.content.metadata;
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| 
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| import java.io.Serializable;
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| import java.util.HashMap;
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| import java.util.Map;
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| import java.util.Set;
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| 
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| import org.alfresco.repo.content.ContentWorker;
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| import org.alfresco.service.cmr.repository.ContentIOException;
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| import org.alfresco.service.cmr.repository.ContentReader;
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| import org.alfresco.service.namespace.QName;
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| 
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| /**
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|  * Interface for document property extracters.
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|  * <p>
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|  * Please pardon the incorrect spelling of <i>extractor</i>.
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|  * 
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|  * @author Jesper Steen Møller
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|  * @author Derek Hulley
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|  */
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| public interface MetadataExtracter extends ContentWorker
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| {
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|     /**
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|      * A enumeration of functional property overwrite policies.  These determine whether extracted properties are
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|      * written into the property map or not.
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|      * 
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|      * @author Derek Hulley
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|      * @author Jesper Steen Møller
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|      */
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|     public enum OverwritePolicy
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|     {
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|         /**
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|          * This policy puts the new value if:
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|          * <ul>
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|          *   <li>the extracted property is not null</li>
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|          * </ul>
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|          */
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|         EAGER
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|         {
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|             @Override
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|             public Map<QName, Serializable> applyProperties(Map<QName, Serializable> extractedProperties, Map<QName, Serializable> targetProperties)
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|             {
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|                 Map<QName, Serializable> modifiedProperties = new HashMap<QName, Serializable>(7);
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|                 for (Map.Entry<QName, Serializable> entry : extractedProperties.entrySet())
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|                 {
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|                     QName propertyQName = entry.getKey();
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|                     Serializable extractedValue = entry.getValue();
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|                     // Ignore null extracted value
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|                     if (extractedValue == null)
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|                     {
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|                         continue;
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|                     }
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|                     targetProperties.put(propertyQName, extractedValue);
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|                     modifiedProperties.put(propertyQName, extractedValue);
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|                 }
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|                 return modifiedProperties;
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|             }
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|         },
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|         /**
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|          * This policy puts the new value if:
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|          * <ul>
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|          *   <li>the extracted property is not null</li>
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|          *   <li>there is no target key for the property</li>
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|          *   <li>the target value is null</li>
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|          *   <li>the string representation of the target value is an empty string</li>
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|          * </ul>
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|          */
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|         PRAGMATIC
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|         {
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|             @Override
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|             public Map<QName, Serializable> applyProperties(Map<QName, Serializable> extractedProperties, Map<QName, Serializable> targetProperties)
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|             {
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|                 /*
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|                  * Negative and positive checks are mixed in the loop.
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|                  */
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|                 Map<QName, Serializable> modifiedProperties = new HashMap<QName, Serializable>(7);
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|                 for (Map.Entry<QName, Serializable> entry : extractedProperties.entrySet())
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|                 {
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|                     QName propertyQName = entry.getKey();
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|                     Serializable extractedValue = entry.getValue();
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|                     // Ignore null extracted value
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|                     if (extractedValue == null)
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|                     {
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|                         continue;
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|                     }
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|                     // Handle the shortcut cases where the target value is missing or null
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|                     if (!targetProperties.containsKey(propertyQName))
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|                     {
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|                         // There is nothing currently
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|                         targetProperties.put(propertyQName, extractedValue);
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|                         modifiedProperties.put(propertyQName, extractedValue);
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|                         continue;
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|                     }
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|                     Serializable originalValue = targetProperties.get(propertyQName);
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|                     if (originalValue == null)
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|                     {
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|                         // The current value is null
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|                         targetProperties.put(propertyQName, extractedValue);
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|                         modifiedProperties.put(propertyQName, extractedValue);
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|                         continue;
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|                     }
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|                     // Check the string representation
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|                     if (originalValue instanceof String)
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|                     {
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|                         String originalValueStr = (String) originalValue;
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|                         if (originalValueStr != null && originalValueStr.length() > 0)
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|                         {
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|                             // The original value is non-trivial
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|                             continue;
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|                         }
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|                         else
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|                         {
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|                             // The original string is trivial
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|                             targetProperties.put(propertyQName, extractedValue);
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|                             modifiedProperties.put(propertyQName, extractedValue);
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|                             continue;
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|                         }
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|                     }
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|                     // We have some other object as the original value, so keep it
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|                 }
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|                 return modifiedProperties;
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|             }
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|         },
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|         /**
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|          * This policy only puts the extracted value if there is no value (null or otherwise) in the properties map.
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|          * It is assumed that the mere presence of a property key is enough to inidicate that the target property
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|          * is as intented.
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|          * This policy puts the new value if:
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|          * <ul>
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|          *   <li>the extracted property is not null</li>
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|          *   <li>there is no target key for the property</li>
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|          * </ul>
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|          */
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|         CAUTIOUS
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|         {
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|             @Override
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|             public Map<QName, Serializable> applyProperties(Map<QName, Serializable> extractedProperties, Map<QName, Serializable> targetProperties)
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|             {
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|                 Map<QName, Serializable> modifiedProperties = new HashMap<QName, Serializable>(7);
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|                 for (Map.Entry<QName, Serializable> entry : extractedProperties.entrySet())
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|                 {
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|                     QName propertyQName = entry.getKey();
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|                     Serializable extractedValue = entry.getValue();
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|                     // Ignore null extracted value
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|                     if (extractedValue == null)
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|                     {
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|                         continue;
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|                     }
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|                     // Is the key present in the target values
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|                     if (targetProperties.containsKey(propertyQName))
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|                     {
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|                         // Cautiously bypass the value as there is one already
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|                         continue;
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|                     }
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|                     targetProperties.put(propertyQName, extractedValue);
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|                     modifiedProperties.put(propertyQName, extractedValue);
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|                 }
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|                 return modifiedProperties;
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|             }
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|         };
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| 
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|         /**
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|          * Apply the overwrite policy for the extracted properties.
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|          * 
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|          * @return
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|          *          Returns a map of all properties that were applied to the target map.  If the result is
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|          *          an empty map, then the target map remains unchanged.
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|          */
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|         public Map<QName, Serializable> applyProperties(Map<QName, Serializable> extractedProperties, Map<QName, Serializable> targetProperties)
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|         {
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|             throw new UnsupportedOperationException("Override this method");
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|         }
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|     };
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|     
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|     /**
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|      * Get an estimate of the extracter's reliability on a scale from 0.0 to 1.0.
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|      * 
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|      * @param mimetype      the mimetype to check
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|      * @return              Returns a reliability indicator from 0.0 to 1.0
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|      * 
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|      * @deprecated  This method is replaced by {@link #isSupported(String)}
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|      */
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|     public double getReliability(String mimetype);
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|     
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|     /**
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|      * Determines if the extracter works against the given mimetype.
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|      * 
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|      * @param mimetype      the document mimetype
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|      * @return Returns      <tt>true</tt> if the mimetype is supported, otherwise <tt>false</tt>.
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|      */
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|     public boolean isSupported(String mimetype);
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| 
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|     /**
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|      * Provides an estimate, usually a worst case guess, of how long an
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|      * extraction will take.
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|      * <p>
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|      * This method is used to determine, up front, which of a set of equally
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|      * reliant transformers will be used for a specific extraction.
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|      * 
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|      * @return Returns the approximate number of milliseconds per transformation
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|      * 
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|      * @deprecated          Generally not useful or used.  Extraction is normally specifically configured.
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|      */
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|     public long getExtractionTime();
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| 
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|     /**
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|      * Extracts the metadata values from the content provided by the reader and source
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|      * mimetype to the supplied map.  The internal mapping and {@link OverwritePolicy overwrite policy}
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|      * between document metadata and system metadata will be used.
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|      * <p>
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|      * The extraction viability can be determined by an up front call to {@link #isSupported(String)}.
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|      * <p>
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|      * The source mimetype <b>must</b> be available on the
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|      * {@link org.alfresco.service.cmr.repository.ContentAccessor#getMimetype()} method
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|      * of the reader.
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|      * 
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|      * @param reader                the source of the content
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|      * @param destination           the map of properties to populate (essentially a return value)
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|      * @return                      Returns a map of all properties on the destination map that were
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|      *                              added or modified.  If the return map is empty, then no properties
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|      *                              were modified.
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|      * @throws ContentIOException   if a detectable error occurs
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|      * 
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|      * @see #extract(ContentReader, OverwritePolicy, Map, Map)
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|      */
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|     public Map<QName, Serializable> extract(ContentReader reader, Map<QName, Serializable> destination);
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| 
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|     /**
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|      * Extracts the metadata values from the content provided by the reader and source
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|      * mimetype to the supplied map.
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|      * <p>
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|      * The extraction viability can be determined by an up front call to {@link #isSupported(String)}.
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|      * <p>
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|      * The source mimetype <b>must</b> be available on the
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|      * {@link org.alfresco.service.cmr.repository.ContentAccessor#getMimetype()} method
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|      * of the reader.
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|      * 
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|      * @param reader                the source of the content
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|      * @param overwritePolicy       the policy stipulating how the system properties must be
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|      *                              overwritten if present
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|      * @param destination           the map of properties to populate (essentially a return value)
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|      * @return                      Returns a map of all properties on the destination map that were
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|      *                              added or modified.  If the return map is empty, then no properties
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|      *                              were modified.
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|      * @throws ContentIOException   if a detectable error occurs
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|      * 
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|      * @see #extract(ContentReader, OverwritePolicy, Map, Map)
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|      */
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|     public Map<QName, Serializable> extract(
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|             ContentReader reader,
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|             OverwritePolicy overwritePolicy,
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|             Map<QName, Serializable> destination);
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| 
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|     /**
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|      * Extracts the metadata from the content provided by the reader and source
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|      * mimetype to the supplied map.  The mapping from document metadata to system metadata
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|      * is explicitly provided.  The {@link OverwritePolicy overwrite policy} is also explictly
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|      * set.
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|      * <p>
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|      * The extraction viability can be determined by an up front call to
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|      * {@link #isSupported(String)}.
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|      * <p>
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|      * The source mimetype <b>must</b> be available on the
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|      * {@link org.alfresco.service.cmr.repository.ContentAccessor#getMimetype()} method
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|      * of the reader.
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|      * 
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|      * @param reader                the source of the content
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|      * @param overwritePolicy       the policy stipulating how the system properties must be
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|      *                              overwritten if present
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|      * @param destination           the map of properties to populate (essentially a return value)
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|      * @param mapping               a mapping of document-specific properties to system properties.
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|      * @return                      Returns a map of all properties on the destination map that were
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|      *                              added or modified.  If the return map is empty, then no properties
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|      *                              were modified.
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|      * @throws ContentIOException   if a detectable error occurs
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|      * 
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|      * @see #extract(ContentReader, Map)
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|      */
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|     public Map<QName, Serializable> extract(
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|             ContentReader reader,
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|             OverwritePolicy overwritePolicy,
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|             Map<QName, Serializable> destination,
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|             Map<String, Set<QName>> mapping);
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| }
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