From 7c279747beb43c7e88633a6228a155a30e6834f7 Mon Sep 17 00:00:00 2001 From: Benjamin Culkin Date: Mon, 27 May 2024 11:38:33 -0400 Subject: Initial import --- .../foundation/collections/IterableResultSet.java | 132 +++++++++++++++++++++ 1 file changed, 132 insertions(+) create mode 100644 israfil-foundation-collections/src/main/java/net/israfil/foundation/collections/IterableResultSet.java (limited to 'israfil-foundation-collections/src/main/java/net/israfil/foundation/collections/IterableResultSet.java') diff --git a/israfil-foundation-collections/src/main/java/net/israfil/foundation/collections/IterableResultSet.java b/israfil-foundation-collections/src/main/java/net/israfil/foundation/collections/IterableResultSet.java new file mode 100644 index 0000000..9258c6f --- /dev/null +++ b/israfil-foundation-collections/src/main/java/net/israfil/foundation/collections/IterableResultSet.java @@ -0,0 +1,132 @@ +/* + * Copyright (c) 2006 Israfil Consulting Services Corporation + * Copyright (c) 2006 Christian Edward Gruber + * All Rights Reserved + * + * This software is licensed under the Berkeley Standard Distribution license, + * (BSD license), as defined below: + * + * 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. Neither the name of Israfil Consulting Services nor the names of its contributors + * may be used to endorse or promote products derived from this software without + * specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED + * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, + * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, + * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, + * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, + * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY + * OF SUCH DAMAGE. + * + * $Id: IterableResultSet.java 26 2006-02-13 16:35:44Z cgruber $ + */ +package net.israfil.foundation.collections; + +import java.lang.ref.WeakReference; +import java.sql.ResultSet; +import java.sql.SQLException; +import java.util.HashMap; +import java.util.Iterator; +import java.util.Map; +import java.util.WeakHashMap; +import java.util.logging.Level; +import java.util.logging.Logger; + +/** + * A simple wrapper that provides an Iterable implementation back-ended + * by a result-set. Allows a ResultSet to be used in a JDK 5.0 extended + * for-loop syntax. + * + * No result set can have more than one Iterable wrapper around it at a time. + * However, it is impossible for this object to know implicitly when it is + * no longer required (to free the reference). Therefore, when this + * wrapper is concluded, it should be disposed of via the dispose() method. + * + * @author Christian Edward Gruber + */ +public class IterableResultSet implements Iterable> { + + protected static final Map iterables = new WeakHashMap(); + protected final WeakReference resultRef; + + public IterableResultSet(ResultSet result) { + if (iterables.containsKey(result)) throw new RuntimeException("Cannot have two IterableResultSet wrappers around the same resultset."); + this.resultRef = new WeakReference(result); + } + + public Iterator> iterator() { + if (resultRef.get() == null) throw new RuntimeException("ResultSet object not available to iterate."); + return new ResultSetIterator(resultRef.get()); + } + + public void dispose() { + ResultSet rs = resultRef.get(); + if (rs == null) return; + if (iterables.containsKey(rs)) { + iterables.get(rs).dispose(); + } + resultRef.clear(); + } + + public static class ResultSetIterator implements Iterator> { + private static final Logger logger = Logger.getLogger(ResultSetIterator.class.getName()); + protected ResultSet result; + + boolean hasNext = true; + + + public ResultSetIterator(ResultSet result) { + this.result = result; + try { + hasNext = result.first(); + } catch (SQLException e) { + throw new RuntimeException(e); + } + } + + public boolean hasNext() { + return hasNext; + } + + public Map next() { + try { + Map row = new HashMap(); + for(int i = 1; i <= result.getMetaData().getColumnCount(); i++) { + row.put(result.getMetaData().getColumnName(i),result.getObject(i)); + } + hasNext = result.next(); + return row; + } catch (SQLException e) { + logger.log(Level.FINER,"SQLException thrown while iterating across result set.",e); + return null; + } + } + + public void remove() { + throw new UnsupportedOperationException("Removal of records from underlying result set not supported."); + } + + public void dispose() { + if (iterables.containsKey(result)) iterables.remove(result); + result = null; + } + + public void finalize() throws Throwable { + dispose(); + super.finalize(); + } + } +} + + -- cgit v1.2.3