Example usage for org.hibernate ScrollableResults previous

Introduction

In this page you can find the example usage for org.hibernate ScrollableResults previous.

Prototype

boolean previous();

Source Link

Document

Retreat to the previous result.

Usage

From source file:com.liferay.jbpm.util.QueryUtil.java

License:Open Source License

public static Comparable<?>[] getPrevAndNext(Query query, int count, OrderByComparator obc,
        Comparable<?> comparable) {

    int pos = count;
    int boundary = 0;

    Comparable<?>[] array = new Comparable[3];

    ScrollableResults sr = query.scroll();

    if (sr.first()) {
        while (true) {
            Object obj = sr.get(0);

            if (obj == null) {
                if (_log.isWarnEnabled()) {
                    _log.warn("Object is null");
                }//from w  ww  . j  a v  a  2  s .  c o  m

                break;
            }

            Comparable<?> curComparable = (Comparable<?>) obj;

            int value = obc.compare(comparable, curComparable);

            if (_log.isDebugEnabled()) {
                _log.debug("Comparison result is " + value);
            }

            if (value == 0) {
                if (!comparable.equals(curComparable)) {
                    break;
                }

                array[1] = curComparable;

                if (sr.previous()) {
                    array[0] = (Comparable<?>) sr.get(0);
                }

                sr.next();

                if (sr.next()) {
                    array[2] = (Comparable<?>) sr.get(0);
                }

                break;
            }

            if (pos == 1) {
                break;
            }

            pos = (int) Math.ceil(pos / 2.0);

            int scrollPos = pos;

            if (value < 0) {
                scrollPos = scrollPos * -1;
            }

            boundary += scrollPos;

            if (boundary < 0) {
                scrollPos = scrollPos + (boundary * -1) + 1;

                boundary = 0;
            }

            if (boundary > count) {
                scrollPos = scrollPos - (boundary - count);

                boundary = scrollPos;
            }

            if (_log.isDebugEnabled()) {
                _log.debug("Scroll " + scrollPos);
            }

            if (!sr.scroll(scrollPos)) {
                if (value < 0) {
                    if (!sr.next()) {
                        break;
                    }
                } else {
                    if (!sr.previous()) {
                        break;
                    }
                }
            }
        }
    }

    return array;
}

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From source file:edu.utah.further.ds.impl.executor.db.hibernate.criteria.HibernateCriteriaScrollableResultsExecutor.java

License:Apache License

/**
 * @param request//  w w  w  .j  a v a2 s  . co  m
 * @return
 * @see edu.utah.further.core.chain.AbstractRequestHandler#process(edu.utah.further.core.api.chain.ChainRequest)
 */
@Override
public boolean process(final ChainRequest request) {
    final QueryExecutionRequest executionRequest = new QueryExecutionRequest(request);
    final GenericCriteria criteria = executionRequest.getResult();
    final ScrollableResults results = getResultListFromHibernate(criteria);
    executionRequest.setResult(results);
    executionRequest.setStatus("Executed query @ " + TimeService.getDate());
    // Hibernate's ScrollableResults interface has no hasNext() or peek(), so go one
    // row forward (if exists) and then back all the way so that we don't miss the
    // first row in subsequent processors
    final boolean hasNext = results.next();
    if (hasNext) {
        results.previous();
    }
    return hasNext;
}

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