com.hs.mail.imap.dao.AbstractDao.java Source code

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/*
 * Copyright 2010 the original author or authors.
 * 
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
package com.hs.mail.imap.dao;

import org.apache.commons.lang.StringUtils;
import org.springframework.dao.DataAccessException;
import org.springframework.dao.EmptyResultDataAccessException;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.jdbc.core.support.JdbcDaoSupport;

/**
 * Convenient super class for JDBC-based data access objects.
 * 
 * @author Won Chul Doh
 * @since Feb 11, 2010
 *
 */
public abstract class AbstractDao extends JdbcDaoSupport {

    /**
     * Query given SQL to create a prepared statement from SQL and a list of
     * arguments to bind to the query, mapping a single result row to a Java
     * object via a RowMapper.
     * 
     * @param sql
     *            SQL query to execute
     * @param args
     *            arguments to bind to the query (leaving it to the
     *            PreparedStatement to guess the corresponding SQL type)
     * @param rowMapper
     *            object that will map one object per row
     * @return the single mapped object or null if the query does not return any
     *         row
     * @throws DataAccessException
     *             if the query fails
     */
    protected Object queryForObject(String sql, Object[] args, RowMapper rowMapper) throws DataAccessException {
        try {
            return getJdbcTemplate().queryForObject(sql, args, rowMapper);
        } catch (EmptyResultDataAccessException ex) {
            return null;
        }
    }

    /**
     * Query given SQL to create a prepared statement from SQL and a list of
     * arguments to bind to the query, resulting in a long value. The query is
     * expected to be a single row/single column query that results in a long
     * value.
     * 
     * @param sql
     *            SQL query to execute
     * @param args
     *            arguments to bind to the query (leaving it to the
     *            PreparedStatement to guess the corresponding SQL type)
     * @return the long value, or 0 in case of SQL NULL or if the query does not
     *         return any row
     * @throws DataAccessException
     *             if query fails
     */
    protected long queryForLong(String sql, Object[] args) throws DataAccessException {
        try {
            return getJdbcTemplate().queryForLong(sql, args);
        } catch (EmptyResultDataAccessException ex) {
            return 0;
        }
    }

    /**
     * Query given SQL to create a prepared statement from SQL and a list of
     * arguments to bind to the query, resulting in an int value. The query is
     * expected to be a single row/single column query that results in an int
     * value.
     * 
     * @param sql
     *            SQL query to execute
     * @param args
     *            arguments to bind to the query (leaving it to the
     *            PreparedStatement to guess the corresponding SQL type)
     * @return the int value, or 0 in case of SQL NULL or if the query does not
     * @throws DataAccessException
     *             if query fails
     */
    protected int queryForInt(String sql, Object[] args) throws DataAccessException {
        try {
            return getJdbcTemplate().queryForInt(sql, args);
        } catch (EmptyResultDataAccessException ex) {
            return 0;
        }
    }

    protected static String escape(String param) {
        return StringUtils.replace(StringUtils.replace(param, "_", "\\_"), "%", "\\%");
    }

    protected static String duplicate(String[] fields, Object[] params, int start) {
        StringBuffer buffer = new StringBuffer("(");
        for (int i = 0; i < fields.length; i++) {
            if (i > 0)
                buffer.append(",");
            buffer.append("?");
            params[i + start] = fields[i];
        }
        buffer.append(")");
        return buffer.toString();
    }

}