samskivert
1a0c3cc241
of a checked exception. Invariably, we don't do anything with our PersistenceExceptions except let them percolate all the way to the top and then log a warning. We can probably automate the process of logging a warning with useful information and save ourselves the trouble of doing it manually everywhere. git-svn-id: https://samskivert.googlecode.com/svn/trunk@2376 6335cc39-0255-0410-8fd6-9bcaacd3b74c
111 lines
3.5 KiB
Java
111 lines
3.5 KiB
Java
//
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// $Id$
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//
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// samskivert library - useful routines for java programs
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// Copyright (C) 2006-2007 Michael Bayne, Pär Winzell
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//
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// This library is free software; you can redistribute it and/or modify it
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// under the terms of the GNU Lesser General Public License as published
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// by the Free Software Foundation; either version 2.1 of the License, or
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// (at your option) any later version.
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//
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// This library 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 GNU
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// 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
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// License along with this library; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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package com.samskivert.jdbc.depot;
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import java.sql.Connection;
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import java.sql.PreparedStatement;
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import java.sql.ResultSet;
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import java.sql.SQLException;
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import com.samskivert.jdbc.DatabaseLiaison;
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import com.samskivert.jdbc.JDBCUtil;
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import com.samskivert.jdbc.depot.clause.QueryClause;
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import com.samskivert.jdbc.depot.clause.SelectClause;
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/**
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* The implementation of {@link DepotRepository#find) functionality.
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*/
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public class FindOneQuery<T extends PersistentRecord>
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implements Query<T>
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{
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public FindOneQuery (PersistenceContext ctx, Class<T> type, QueryClause[] clauses)
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throws DatabaseException
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{
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_marsh = ctx.getMarshaller(type);
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_select = new SelectClause<T>(type, _marsh.getFieldNames(), clauses);
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WhereClause where = _select.getWhereClause();
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if (where != null) {
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_select.getWhereClause().validateQueryType(type); // sanity check
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}
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_builder = ctx.getSQLBuilder(DepotTypes.getDepotTypes(ctx, _select));
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_builder.newQuery(_select);
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}
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// from Query
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public CacheKey getCacheKey ()
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{
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WhereClause where = _select.getWhereClause();
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if (where != null && where instanceof CacheKey) {
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return (CacheKey) where;
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}
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return null;
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}
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// from Query
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public T invoke (Connection conn, DatabaseLiaison liaison) throws SQLException
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{
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PreparedStatement stmt = _builder.prepare(conn);
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try {
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T result = null;
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ResultSet rs = stmt.executeQuery();
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if (rs.next()) {
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result = _marsh.createObject(rs);
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}
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// TODO: if (rs.next()) issue warning?
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rs.close();
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return result;
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} finally {
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JDBCUtil.close(stmt);
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}
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}
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// from Query
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public void updateCache (PersistenceContext ctx, T result)
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{
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CacheKey key = getCacheKey();
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if (key == null) {
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// no row-specific cache key was given
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if (result == null || !_marsh.hasPrimaryKey()) {
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return;
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}
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// if we can, create a key from what was actually returned
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key = _marsh.getPrimaryKey(result);
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}
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ctx.cacheStore(key, (result != null) ? result.clone() : null);
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}
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// from Query
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public T transformCacheHit (CacheKey key, T value)
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{
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if (value == null) {
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return null;
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}
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// we do not want to return a reference to the actual cached entity so we clone it
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@SuppressWarnings("unchecked") T cvalue = (T) value.clone();
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return cvalue;
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}
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protected DepotMarshaller<T> _marsh;
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protected SelectClause<T> _select;
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protected SQLBuilder _builder;
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}
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