ScalarHandler.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work
 * for additional information regarding copyright ownership. The ASF licenses this file to You 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 org.apache.commons.dbutils.handlers;

import java.sql.ResultSet;
import java.sql.SQLException;

import org.apache.commons.dbutils.ResultSetHandler;

import com.lizard.fastdb.jdbc.JdbcUtil;

/**
 * <code>ResultSetHandler</code> implementation that converts one <code>ResultSet</code> column into an Object. This class is thread safe.
 * 
 * @see org.apache.commons.dbutils.ResultSetHandler
 */
public class ScalarHandler implements ResultSetHandler<Object>
{

	/**
	 * The column number to retrieve.
	 */
	private final int		columnIndex;

	/**
	 * The column name to retrieve. Either columnName or columnIndex will be used but never both.
	 */
	private final String	columnName;

	/**
	 * Creates a new instance of ScalarHandler. The first column will be returned from <code>handle()</code>.
	 */
	public ScalarHandler()
	{
		this(1, null);
	}

	/**
	 * Creates a new instance of ScalarHandler.
	 * 
	 * @param columnIndex The index of the column to retrieve from the <code>ResultSet</code>.
	 */
	public ScalarHandler(int columnIndex)
	{
		this(columnIndex, null);
	}

	/**
	 * Creates a new instance of ScalarHandler.
	 * 
	 * @param columnName The name of the column to retrieve from the <code>ResultSet</code>.
	 */
	public ScalarHandler(String columnName)
	{
		this(1, columnName);
	}

	/**
	 * Helper constructor
	 * 
	 * @param columnIndex The index of the column to retrieve from the <code>ResultSet</code>.
	 * @param columnName The name of the column to retrieve from the <code>ResultSet</code>.
	 */
	private ScalarHandler(int columnIndex, String columnName)
	{
		this.columnIndex = columnIndex;
		this.columnName = columnName;
	}

	/**
	 * Returns one <code>ResultSet</code> column as an object via the <code>ResultSet.getObject()</code> method that performs type conversions.
	 * 
	 * @param rs <code>ResultSet</code> to process.
	 * @return The column or <code>null</code> if there are no rows in the <code>ResultSet</code>.
	 * @throws SQLException if a database access error occurs
	 * @see org.apache.commons.dbutils.ResultSetHandler#handle(java.sql.ResultSet)
	 */
	public Object handle(ResultSet rs) throws SQLException
	{
		/*
		 * if (rs.next()) { if (this.columnName == null) { return rs.getObject(this.columnIndex); } else { return rs.getObject(this.columnName); } }
		 * else { return null; }
		 */

		// SHEN.GANG 增加是否为浮点数判断
		// 判断数值精度，看是否是浮点数
		if (rs.next())
		{
			Object obj = null;

			if (this.columnName == null)
			{
				obj = rs.getObject(this.columnIndex);
			}
			else
			{
				obj = rs.getObject(this.columnName);
			}

			obj = JdbcUtil.processBigDecimal(obj, rs, this.columnIndex);

			return obj;
		}
		else
		{
			return null;
		}
	}
}