ResultSetDynaClass.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.beanutils2.sql;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Iterator;
import java.util.Objects;
import org.apache.commons.beanutils2.DynaBean;
import org.apache.commons.beanutils2.DynaClass;
/**
* <p>
* Implements {@link DynaClass} for DynaBeans that wrap the {@code java.sql.Row</code> objects of a <code>java.sql.ResultSet}. 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} returned by the {@code iterator()} 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>
* List 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>
*/
public class ResultSetDynaClass extends AbstractJdbcDynaClass {
private static final long serialVersionUID = 1L;
/**
* <p>
* The {@code ResultSet} we are wrapping.
* </p>
*/
protected ResultSet resultSet;
/**
* <p>
* Constructs a new ResultSetDynaClass for the specified {@code ResultSet}. The property names corresponding to column names in the result set will be lower
* cased.
* </p>
*
* @param resultSet The result set to be wrapped
* @throws NullPointerException if {@code resultSet} is {@code null}
* @throws SQLException if the metadata for this result set cannot be introspected
*/
public ResultSetDynaClass(final ResultSet resultSet) throws SQLException {
this(resultSet, true);
}
/**
* <p>
* Constructs a new ResultSetDynaClass for the specified {@code ResultSet}. The property names corresponding to the column names in the result set will be
* lower cased or not, depending on the specified {@code lowerCase} value.
* </p>
*
* <p>
* <strong>WARNING</strong> - If you specify {@code false} for {@code lowerCase}, 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?
* @throws NullPointerException if {@code resultSet} is {@code null}
* @throws SQLException if the metadata for this result set cannot be introspected
*/
public ResultSetDynaClass(final ResultSet resultSet, final boolean lowerCase) throws SQLException {
this(resultSet, lowerCase, false);
}
/**
* <p>
* Constructs a new ResultSetDynaClass for the specified {@code ResultSet}. The property names corresponding to the column names in the result set will be
* lower cased or not, depending on the specified {@code lowerCase} value.
* </p>
*
* <p>
* <strong>WARNING</strong> - If you specify {@code false} for {@code lowerCase}, 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
* @throws NullPointerException if {@code resultSet} is {@code null}
* @throws SQLException if the metadata for this result set cannot be introspected
* @since 1.8.3
*/
public ResultSetDynaClass(final ResultSet resultSet, final boolean lowerCase, final boolean useColumnLabel) throws SQLException {
this.resultSet = Objects.requireNonNull(resultSet, "resultSet");
this.lowerCase = lowerCase;
setUseColumnLabel(useColumnLabel);
introspect(resultSet);
}
/**
* Gets 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
*/
@SuppressWarnings("resource") // getResultSet() does not allocate.
public Object getObjectFromResultSet(final String name) throws SQLException {
return getObject(getResultSet(), name);
}
/**
* <p>
* Gets the result set we are wrapping.
* </p>
*/
ResultSet getResultSet() {
return this.resultSet;
}
/**
* <p>
* Return an {@code Iterator} of {@link DynaBean} instances for each row of the wrapped {@code ResultSet}, in "forward" order. Unless the underlying result
* set supports scrolling, this method should be called only once.
* </p>
*
* @return An {@code Iterator} of {@link DynaBean} instances
*/
public Iterator<DynaBean> iterator() {
return new ResultSetIterator(this);
}
/**
* <p>
* Loads the class of the given name which by default uses the class loader used to load this library. Derivations 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
*/
@Override
protected Class<?> loadClass(final String className) throws SQLException {
try {
return getClass().getClassLoader().loadClass(className);
} catch (final Exception e) {
throw new SQLException("Cannot load column class '" + className + "': " + e);
}
}
}