/*
* 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.beanutils;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Iterator;
/**
* <p>Implementation of <code>DynaClass</code> for DynaBeans that wrap the
* <code>java.sql.Row</code> objects of a <code>java.sql.ResultSet</code>.
* The normal usage pattern is something like:</p>
* <pre>
* ResultSet rs = ...;
* ResultSetDynaClass rsdc = new ResultSetDynaClass(rs);
* Iterator rows = rsdc.iterator();
* while (rows.hasNext()) {
* DynaBean row = (DynaBean) rows.next();
* ... process this row ...
* }
* rs.close();
* </pre>
*
* <p>Each column in the result set will be represented as a DynaBean
* property of the corresponding name (optionally forced to lower case
* for portability).</p>
*
* <p><strong>WARNING</strong> - Any {@link DynaBean} instance returned by
* this class, or from the <code>Iterator</code> returned by the
* <code>iterator()</code> method, is directly linked to the row that the
* underlying result set is currently positioned at. This has the following
* implications:</p>
* <ul>
* <li>Once you retrieve a different {@link DynaBean} instance, you should
* no longer use any previous instance.</li>
* <li>Changing the position of the underlying result set will change the
* data that the {@link DynaBean} references.</li>
* <li>Once the underlying result set is closed, the {@link DynaBean}
* instance may no longer be used.</li>
* </ul>
*
* <p>Any database data that you wish to utilize outside the context of the
* current row of an open result set must be copied. For example, you could
* use the following code to create standalone copies of the information in
* a result set:</p>
* <pre>
* ArrayList results = new ArrayList(); // To hold copied list
* ResultSetDynaClass rsdc = ...;
* DynaProperty[] properties = rsdc.getDynaProperties();
* BasicDynaClass bdc =
* new BasicDynaClass("foo", BasicDynaBean.class,
* rsdc.getDynaProperties());
* Iterator rows = rsdc.iterator();
* while (rows.hasNext()) {
* DynaBean oldRow = (DynaBean) rows.next();
* DynaBean newRow = bdc.newInstance();
* PropertyUtils.copyProperties(newRow, oldRow);
* results.add(newRow);
* }
* </pre>
*
* @author Craig R. McClanahan
* @version $Revision: 926685 $ $Date: 2010-03-23 17:59:08 +0000 (Tue, 23 Mar 2010) $
*/
public class ResultSetDynaClass extends JDBCDynaClass implements DynaClass {
// ----------------------------------------------------------- Constructors
/**
* <p>Construct a new ResultSetDynaClass for the specified
* <code>ResultSet</code>. The property names corresponding
* to column names in the result set will be lower cased.</p>
*
* @param resultSet The result set to be wrapped
*
* @exception NullPointerException if <code>resultSet</code>
* is <code>null</code>
* @exception SQLException if the metadata for this result set
* cannot be introspected
*/
public ResultSetDynaClass(ResultSet resultSet) throws SQLException {
this(resultSet, true);
}
/**
* <p>Construct a new ResultSetDynaClass for the specified
* <code>ResultSet</code>. The property names corresponding
* to the column names in the result set will be lower cased or not,
* depending on the specified <code>lowerCase</code> value.</p>
*
* <p><strong>WARNING</strong> - If you specify <code>false</code>
* for <code>lowerCase</code>, the returned property names will
* exactly match the column names returned by your JDBC driver.
* Because different drivers might return column names in different
* cases, the property names seen by your application will vary
* depending on which JDBC driver you are using.</p>
*
* @param resultSet The result set to be wrapped
* @param lowerCase Should property names be lower cased?
*
* @exception NullPointerException if <code>resultSet</code>
* is <code>null</code>
* @exception SQLException if the metadata for this result set
* cannot be introspected
*/
public ResultSetDynaClass(ResultSet resultSet, boolean lowerCase)
throws SQLException {
this(resultSet, lowerCase, false);
}
/**
* <p>Construct a new ResultSetDynaClass for the specified
* <code>ResultSet</code>. The property names corresponding
* to the column names in the result set will be lower cased or not,
* depending on the specified <code>lowerCase</code> value.</p>
*
* <p><strong>WARNING</strong> - If you specify <code>false</code>
* for <code>lowerCase</code>, the returned property names will
* exactly match the column names returned by your JDBC driver.
* Because different drivers might return column names in different
* cases, the property names seen by your application will vary
* depending on which JDBC driver you are using.</p>
*
* @param resultSet The result set to be wrapped
* @param lowerCase Should property names be lower cased?
* @param useColumnLabel true if the column label should be used, otherwise false
*
* @exception NullPointerException if <code>resultSet</code>
* is <code>null</code>
* @exception SQLException if the metadata for this result set
* cannot be introspected
* @since 1.8.3
*/
public ResultSetDynaClass(ResultSet resultSet, boolean lowerCase, boolean useColumnLabel)
throws SQLException {
if (resultSet == null) {
throw new NullPointerException();
}
this.resultSet = resultSet;
this.lowerCase = lowerCase;
setUseColumnLabel(useColumnLabel);
introspect(resultSet);
}
// ----------------------------------------------------- Instance Variables
/**
* <p>The <code>ResultSet</code> we are wrapping.</p>
*/
protected ResultSet resultSet = null;
// --------------------------------------------------------- Public Methods
/**
* <p>Return an <code>Iterator</code> of {@link DynaBean} instances for
* each row of the wrapped <code>ResultSet</code>, in "forward" order.
* Unless the underlying result set supports scrolling, this method
* should be called only once.</p>
* @return An <code>Iterator</code> of {@link DynaBean} instances
*/
public Iterator iterator() {
return (new ResultSetIterator(this));
}
/**
* Get a value from the {@link ResultSet} for the specified
* property name.
*
* @param name The property name
* @return The value
* @throws SQLException if an error occurs
* @since 1.8.0
*/
public Object getObjectFromResultSet(String name) throws SQLException {
return getObject(getResultSet(), name);
}
// -------------------------------------------------------- Package Methods
/**
* <p>Return the result set we are wrapping.</p>
*/
ResultSet getResultSet() {
return (this.resultSet);
}
// ------------------------------------------------------ Protected Methods
/**
* <p>Loads the class of the given name which by default uses the class loader used
* to load this library.
* Dervations of this class could implement alternative class loading policies such as
* using custom ClassLoader or using the Threads's context class loader etc.
* </p>
* @param className The name of the class to load
* @return The loaded class
* @throws SQLException if the class cannot be loaded
*/
protected Class loadClass(String className) throws SQLException {
try {
return getClass().getClassLoader().loadClass(className);
}
catch (Exception e) {
throw new SQLException("Cannot load column class '" +
className + "': " + e);
}
}
}