Java tutorial
/* ==================================================================== * * The ObjectStyle Group Software License, version 1.1 * ObjectStyle Group - http://objectstyle.org/ * * Copyright (c) 2002-2004, Andrei (Andrus) Adamchik and individual authors * of the software. 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. 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For more * information on the ObjectStyle Group, please see * <http://objectstyle.org/>. */ package org.objectstyle.cayenne.query; import java.util.ArrayList; import java.util.Collection; import java.util.Collections; import java.util.Iterator; import java.util.List; import java.util.Map; import org.apache.commons.collections.IteratorUtils; import org.objectstyle.cayenne.map.DbAttribute; import org.objectstyle.cayenne.map.DbEntity; /** * Batched UPDATE query. * * @author Andriy Shapochka */ public class UpdateBatchQuery extends BatchQuery { private List qualifierSnapshots; private List updateSnapshots; private List updatedAttributes; private List qualifierAttributes; private Collection nullQualifierNames; private List dbAttributes; private Iterator qualifierIterator = IteratorUtils.EMPTY_ITERATOR; private Iterator updateIterator = IteratorUtils.EMPTY_ITERATOR; private Map currentUpdate = Collections.EMPTY_MAP; private Map currentQualifier = Collections.EMPTY_MAP; private boolean usingOptimisticLocking; /** * Creates new UpdateBatchQuery. * * @param dbEntity Table or view to update. * @param qualifierAttributes DbAttributes used in the WHERE clause. * @param nullQualifierNames DbAttribute names in the WHERE clause that have null values. * @param updatedAttribute DbAttributes describing updated columns. * @param batchCapacity Estimated size of the batch. */ public UpdateBatchQuery(DbEntity dbEntity, List qualifierAttributes, List updatedAttribute, Collection nullQualifierNames, int batchCapacity) { super(dbEntity); this.updatedAttributes = updatedAttribute; this.qualifierAttributes = qualifierAttributes; this.nullQualifierNames = nullQualifierNames != null ? nullQualifierNames : Collections.EMPTY_SET; qualifierSnapshots = new ArrayList(batchCapacity); updateSnapshots = new ArrayList(batchCapacity); dbAttributes = new ArrayList(updatedAttributes.size() + qualifierAttributes.size()); dbAttributes.addAll(updatedAttributes); dbAttributes.addAll(qualifierAttributes); } /** * Returns true if a given attribute always has a null value * in the batch. * * @since 1.1 */ public boolean isNull(DbAttribute attribute) { return nullQualifierNames.contains(attribute.getName()); } /** * Returns true if the batch query uses optimistic locking. * * @since 1.1 */ public boolean isUsingOptimisticLocking() { return usingOptimisticLocking; } /** * @since 1.1 */ public void setUsingOptimisticLocking(boolean usingOptimisticLocking) { this.usingOptimisticLocking = usingOptimisticLocking; } public void reset() { qualifierIterator = qualifierSnapshots.iterator(); updateIterator = updateSnapshots.iterator(); currentQualifier = Collections.EMPTY_MAP; currentUpdate = Collections.EMPTY_MAP; } public boolean next() { if (!qualifierIterator.hasNext()) { return false; } currentQualifier = (Map) qualifierIterator.next(); currentQualifier = (currentQualifier != null) ? currentQualifier : Collections.EMPTY_MAP; currentUpdate = (Map) updateIterator.next(); currentUpdate = (currentUpdate != null) ? currentUpdate : Collections.EMPTY_MAP; return true; } public Object getObject(int dbAttributeIndex) { DbAttribute attribute = (DbAttribute) dbAttributes.get(dbAttributeIndex); String name = attribute.getName(); // take value either from updated values or id's, // depending on the index return (dbAttributeIndex < updatedAttributes.size()) ? currentUpdate.get(name) : currentQualifier.get(name); } /** * Adds a parameter row to the batch. * * @param qualifierSnapshot describes WHERE clause of the update; includes PK values and * any attributes used in optimistic locking. * @param updateSnapshot describes updated columns. */ public void add(Map qualifierSnapshot, Map updateSnapshot) { qualifierSnapshots.add(qualifierSnapshot); updateSnapshots.add(updateSnapshot); } public int size() { return qualifierSnapshots.size(); } public List getDbAttributes() { return Collections.unmodifiableList(dbAttributes); } /** * @deprecated Since 1.1 use getQualifierAttributes() that include attributes * used in optimistic locking. */ public List getIdDbAttributes() { return getQualifierAttributes(); } /** * @since 1.1 */ public List getUpdatedAttributes() { return Collections.unmodifiableList(updatedAttributes); } /** * @deprecated Since 1.1 use getUpdatedAttributes(). */ public List getUpdatedDbAttributes() { return Collections.unmodifiableList(updatedAttributes); } /** * @since 1.1 */ public List getQualifierAttributes() { return Collections.unmodifiableList(qualifierAttributes); } /** * Returns a snapshot of the current qualifier values. * * @since 1.1 */ public Map getCurrentQualifier() { return currentQualifier; } }