jdbcutils.java

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/*
 * Copyright 2002-2008 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 org.springframework.jdbc.support;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.math.BigDecimal;
import java.sql.Blob;
import java.sql.Clob;
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
import java.sql.Types;

import javax.sql.DataSource;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.jdbc.CannotGetJdbcConnectionException;
import org.springframework.jdbc.datasource.DataSourceUtils;

/**
 * Generic utility methods for working with JDBC. Mainly for internal use
 * within the framework, but also useful for custom JDBC access code.
 *
 * @author Thomas Risberg
 * @author Juergen Hoeller
 */
public abstract class JdbcUtils {

	/**
	 * Constant that indicates an unknown (or unspecified) SQL type.
	 * @see java.sql.Types
	 */
	public static final int TYPE_UNKNOWN = Integer.MIN_VALUE;


	private static final Log logger = LogFactory.getLog(JdbcUtils.class);


	/**
	 * Close the given JDBC Connection and ignore any thrown exception.
	 * This is useful for typical finally blocks in manual JDBC code.
	 * @param con the JDBC Connection to close (may be <code>null</code>)
	 */
	public static void closeConnection(Connection con) {
		if (con != null) {
			try {
				con.close();
			}
			catch (SQLException ex) {
				logger.debug("Could not close JDBC Connection", ex);
			}
			catch (Throwable ex) {
				// We don't trust the JDBC driver: It might throw RuntimeException or Error.
				logger.debug("Unexpected exception on closing JDBC Connection", ex);
			}
		}
	}

	/**
	 * Close the given JDBC Statement and ignore any thrown exception.
	 * This is useful for typical finally blocks in manual JDBC code.
	 * @param stmt the JDBC Statement to close (may be <code>null</code>)
	 */
	public static void closeStatement(Statement stmt) {
		if (stmt != null) {
			try {
				stmt.close();
			}
			catch (SQLException ex) {
				logger.debug("Could not close JDBC Statement", ex);
			}
			catch (Throwable ex) {
				// We don't trust the JDBC driver: It might throw RuntimeException or Error.
				logger.debug("Unexpected exception on closing JDBC Statement", ex);
			}
		}
	}

	/**
	 * Close the given JDBC ResultSet and ignore any thrown exception.
	 * This is useful for typical finally blocks in manual JDBC code.
	 * @param rs the JDBC ResultSet to close (may be <code>null</code>)
	 */
	public static void closeResultSet(ResultSet rs) {
		if (rs != null) {
			try {
				rs.close();
			}
			catch (SQLException ex) {
				logger.debug("Could not close JDBC ResultSet", ex);
			}
			catch (Throwable ex) {
				// We don't trust the JDBC driver: It might throw RuntimeException or Error.
				logger.debug("Unexpected exception on closing JDBC ResultSet", ex);
			}
		}
	}

	/**
	 * Retrieve a JDBC column value from a ResultSet, using the specified value type.
	 * <p>Uses the specifically typed ResultSet accessor methods, falling back to
	 * {@link #getResultSetValue(java.sql.ResultSet, int)} for unknown types.
	 * <p>Note that the returned value may not be assignable to the specified
	 * required type, in case of an unknown type. Calling code needs to deal
	 * with this case appropriately, e.g. throwing a corresponding exception.
	 * @param rs is the ResultSet holding the data
	 * @param index is the column index
	 * @param requiredType the required value type (may be <code>null</code>)
	 * @return the value object
	 * @throws SQLException if thrown by the JDBC API
	 */
	public static Object getResultSetValue(ResultSet rs, int index, Class requiredType) throws SQLException {
		if (requiredType == null) {
			return getResultSetValue(rs, index);
		}

		Object value = null;
		boolean wasNullCheck = false;

		// Explicitly extract typed value, as far as possible.
		if (String.class.equals(requiredType)) {
			value = rs.getString(index);
		}
		else if (boolean.class.equals(requiredType) || Boolean.class.equals(requiredType)) {
			value = Boolean.valueOf(rs.getBoolean(index));
			wasNullCheck = true;
		}
		else if (byte.class.equals(requiredType) || Byte.class.equals(requiredType)) {
			value = new Byte(rs.getByte(index));
			wasNullCheck = true;
		}
		else if (short.class.equals(requiredType) || Short.class.equals(requiredType)) {
			value = new Short(rs.getShort(index));
			wasNullCheck = true;
		}
		else if (int.class.equals(requiredType) || Integer.class.equals(requiredType)) {
			value = new Integer(rs.getInt(index));
			wasNullCheck = true;
		}
		else if (long.class.equals(requiredType) || Long.class.equals(requiredType)) {
			value = new Long(rs.getLong(index));
			wasNullCheck = true;
		}
		else if (float.class.equals(requiredType) || Float.class.equals(requiredType)) {
			value = new Float(rs.getFloat(index));
			wasNullCheck = true;
		}
		else if (double.class.equals(requiredType) || Double.class.equals(requiredType) ||
				Number.class.equals(requiredType)) {
			value = new Double(rs.getDouble(index));
			wasNullCheck = true;
		}
		else if (byte[].class.equals(requiredType)) {
			value = rs.getBytes(index);
		}
		else if (java.sql.Date.class.equals(requiredType)) {
			value = rs.getDate(index);
		}
		else if (java.sql.Time.class.equals(requiredType)) {
			value = rs.getTime(index);
		}
		else if (java.sql.Timestamp.class.equals(requiredType) || java.util.Date.class.equals(requiredType)) {
			value = rs.getTimestamp(index);
		}
		else if (BigDecimal.class.equals(requiredType)) {
			value = rs.getBigDecimal(index);
		}
		else if (Blob.class.equals(requiredType)) {
			value = rs.getBlob(index);
		}
		else if (Clob.class.equals(requiredType)) {
			value = rs.getClob(index);
		}
		else {
			// Some unknown type desired -> rely on getObject.
			value = getResultSetValue(rs, index);
		}

		// Perform was-null check if demanded (for results that the
		// JDBC driver returns as primitives).
		if (wasNullCheck && value != null && rs.wasNull()) {
			value = null;
		}
		return value;
	}

	/**
	 * Retrieve a JDBC column value from a ResultSet, using the most appropriate
	 * value type. The returned value should be a detached value object, not having
	 * any ties to the active ResultSet: in particular, it should not be a Blob or
	 * Clob object but rather a byte array respectively String representation.
	 * <p>Uses the <code>getObject(index)</code> method, but includes additional "hacks"
	 * to get around Oracle 10g returning a non-standard object for its TIMESTAMP
	 * datatype and a <code>java.sql.Date</code> for DATE columns leaving out the
	 * time portion: These columns will explicitly be extracted as standard
	 * <code>java.sql.Timestamp</code> object.
	 * @param rs is the ResultSet holding the data
	 * @param index is the column index
	 * @return the value object
	 * @throws SQLException if thrown by the JDBC API
	 * @see java.sql.Blob
	 * @see java.sql.Clob
	 * @see java.sql.Timestamp
	 */
	public static Object getResultSetValue(ResultSet rs, int index) throws SQLException {
		Object obj = rs.getObject(index);
		if (obj instanceof Blob) {
			obj = rs.getBytes(index);
		}