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MapPersistence |
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1 /* 2 * Copyright (c) 1998-2001, The University of Sheffield. 3 * 4 * This file is part of GATE (see http://gate.ac.uk/), and is free 5 * software, licenced under the GNU Library General Public License, 6 * Version 2, June 1991 (in the distribution as file licence.html, 7 * and also available at http://gate.ac.uk/gate/licence.html). 8 * 9 * Valentin Tablan 26/10/2001 10 * 11 * $Id: MapPersistence.java,v 1.2 2001/10/29 17:11:26 valyt Exp $ 12 * 13 */ 14 package gate.util.persistence; 15 16 import java.util.*; 17 import java.io.*; 18 19 import gate.persist.PersistenceException; 20 import gate.creole.ResourceInstantiationException; 21 22 public class MapPersistence implements Persistence { 23 /** 24 * Populates this Persistence with the data that needs to be stored from the 25 * original source object. 26 */ 27 public void extractDataFromSource(Object source)throws PersistenceException{ 28 if(! (source instanceof Map)){ 29 throw new UnsupportedOperationException( 30 getClass().getName() + " can only be used for " + 31 Map.class.getName() + 32 " objects!\n" + source.getClass().getName() + 33 " is not a " + Map.class.getName()); 34 } 35 mapType = source.getClass(); 36 37 Map map = (Map)source; 38 List keysList = new ArrayList(); 39 List valuesList = new ArrayList(); 40 localMap = new HashMap(map.size()); 41 //collect the keys in the order given by the entrySet().iterator(); 42 Iterator keyIter = map.keySet().iterator(); 43 while(keyIter.hasNext()){ 44 Object key = keyIter.next(); 45 Object value = map.get(key); 46 47 key = PersistenceManager.getPersistentRepresentation(key); 48 value = PersistenceManager.getPersistentRepresentation(value); 49 localMap.put(key, value); 50 } 51 } 52 53 /** 54 * Creates a new object from the data contained. This new object is supposed 55 * to be a copy for the original object used as source for data extraction. 56 */ 57 public Object createObject()throws PersistenceException, 58 ResourceInstantiationException{ 59 //let's try to create a map of the same type as the original 60 Map result = null; 61 try{ 62 result = (Map)mapType.newInstance(); 63 }catch(Exception e){ 64 } 65 if(result == null) result = new HashMap(localMap.size()); 66 67 //now we have a map let's populate it 68 Iterator keyIter = localMap.keySet().iterator(); 69 while(keyIter.hasNext()){ 70 Object key = keyIter.next(); 71 Object value = localMap.get(key); 72 73 key = PersistenceManager.getTransientRepresentation(key); 74 value = PersistenceManager.getTransientRepresentation(value); 75 result.put(key, value); 76 } 77 78 return result; 79 } 80 81 protected Class mapType; 82 protected HashMap localMap; 83 static final long serialVersionUID = 1835776085941379996L; 84 }
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