Java tutorial
/* This file is part of Subsonic. Subsonic is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. Subsonic is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with Subsonic. If not, see <http://www.gnu.org/licenses/>. Copyright 2009 (C) Sindre Mehus */ package net.sourceforge.subsonic.dao; import java.util.Date; import java.util.List; import java.util.Map; import java.util.concurrent.TimeUnit; import org.springframework.jdbc.core.*; import org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate; import net.sourceforge.subsonic.Logger; /** * Abstract superclass for all DAO's. * * @author Sindre Mehus */ public class AbstractDao { private static final Logger LOG = Logger.getLogger(AbstractDao.class); private DaoHelper daoHelper; /** * Returns a JDBC template for performing database operations. * @return A JDBC template. */ public JdbcTemplate getJdbcTemplate() { return daoHelper.getJdbcTemplate(); } /** * Similar to {@link #getJdbcTemplate()}, but with named parameters. */ public NamedParameterJdbcTemplate getNamedParameterJdbcTemplate() { return daoHelper.getNamedParameterJdbcTemplate(); } protected String questionMarks(String columns) { int count = columns.split(", ").length; StringBuilder builder = new StringBuilder(); for (int i = 0; i < count; i++) { builder.append('?'); if (i < count - 1) { builder.append(", "); } } return builder.toString(); } protected String prefix(String columns, String prefix) { StringBuilder builder = new StringBuilder(); for (String s : columns.split(", ")) { builder.append(prefix).append(".").append(s).append(","); } if (builder.length() > 0) { builder.setLength(builder.length() - 1); } return builder.toString(); } protected int update(String sql, Object... args) { long t = System.nanoTime(); int result = getJdbcTemplate().update(sql, args); log(sql, t); return result; } private void log(String sql, long startTimeNano) { long millis = (System.nanoTime() - startTimeNano) / 1000000L; // Log queries that take more than 2 seconds. if (millis > TimeUnit.SECONDS.toMillis(2L)) { LOG.debug(millis + " ms: " + sql); } } protected <T> List<T> query(String sql, RowMapper rowMapper, Object... args) { long t = System.nanoTime(); List<T> result = getJdbcTemplate().query(sql, args, rowMapper); log(sql, t); return result; } protected <T> List<T> namedQuery(String sql, RowMapper rowMapper, Map<String, Object> args) { long t = System.nanoTime(); List<T> result = getNamedParameterJdbcTemplate().query(sql, args, rowMapper); log(sql, t); return result; } protected List<String> queryForStrings(String sql, Object... args) { long t = System.nanoTime(); List<String> result = getJdbcTemplate().queryForList(sql, args, String.class); log(sql, t); return result; } protected List<Integer> queryForInts(String sql, Object... args) { long t = System.nanoTime(); List<Integer> result = getJdbcTemplate().queryForList(sql, args, Integer.class); log(sql, t); return result; } protected List<String> namedQueryForStrings(String sql, Map<String, Object> args) { long t = System.nanoTime(); List<String> result = getNamedParameterJdbcTemplate().queryForList(sql, args, String.class); log(sql, t); return result; } protected Integer queryForInt(String sql, Integer defaultValue, Object... args) { long t = System.nanoTime(); List<Integer> list = getJdbcTemplate().queryForList(sql, args, Integer.class); Integer result = list.isEmpty() ? defaultValue : list.get(0) == null ? defaultValue : list.get(0); log(sql, t); return result; } protected Integer namedQueryForInt(String sql, Integer defaultValue, Map<String, Object> args) { long t = System.nanoTime(); List<Integer> list = getNamedParameterJdbcTemplate().queryForList(sql, args, Integer.class); Integer result = list.isEmpty() ? defaultValue : list.get(0) == null ? defaultValue : list.get(0); log(sql, t); return result; } protected Date queryForDate(String sql, Date defaultValue, Object... args) { long t = System.nanoTime(); List<Date> list = getJdbcTemplate().queryForList(sql, args, Date.class); Date result = list.isEmpty() ? defaultValue : list.get(0) == null ? defaultValue : list.get(0); log(sql, t); return result; } protected Long queryForLong(String sql, Long defaultValue, Object... args) { long t = System.nanoTime(); List<Long> list = getJdbcTemplate().queryForList(sql, args, Long.class); Long result = list.isEmpty() ? defaultValue : list.get(0) == null ? defaultValue : list.get(0); log(sql, t); return result; } protected <T> T queryOne(String sql, RowMapper rowMapper, Object... args) { List<T> list = query(sql, rowMapper, args); return list.isEmpty() ? null : list.get(0); } protected <T> T namedQueryOne(String sql, RowMapper rowMapper, Map<String, Object> args) { List<T> list = namedQuery(sql, rowMapper, args); return list.isEmpty() ? null : list.get(0); } public void setDaoHelper(DaoHelper daoHelper) { this.daoHelper = daoHelper; } }