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/*
 * 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.io.Serializable;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;


/**
 * 

Implementation of {@link DynaClass} that creates an in-memory collection * of {@link DynaBean}s representing the results of an SQL query. Once the * {@link DynaClass} instance has been created, the JDBC ResultSet * and Statement on which it is based can be closed, and the * underlying Connection can be returned to its connection pool * (if you are using one).

* *

The normal usage pattern is something like:

*
 *   Connection conn = ...;  // Acquire connection from pool
 *   Statement stmt = conn.createStatement();
 *   ResultSet rs = stmt.executeQuery("SELECT ...");
 *   RowSetDynaClass rsdc = new RowSetDynaClass(rs);
 *   rs.close();
 *   stmt.close();
 *   ...;                    // Return connection to pool
 *   List rows = rsdc.getRows();
 *   ...;                   // Process the rows as desired
 * 
* *

Each column in the result set will be represented as a {@link DynaBean} * property of the corresponding name (optionally forced to lower case * for portability). There will be one {@link DynaBean} in the * List returned by getRows() for each * row in the original ResultSet.

* *

In general, instances of {@link RowSetDynaClass} can be serialized * and deserialized, which will automatically include the list of * {@link DynaBean}s representing the data content. The only exception * to this rule would be when the underlying property values that were * copied from the ResultSet originally cannot themselves * be serialized. Therefore, a {@link RowSetDynaClass} makes a very * convenient mechanism for transporting data sets to remote Java-based * application components.

* * @author Craig R. McClanahan * @version $Revision: 556233 $ $Date: 2007-07-14 07:37:06 +0100 (Sat, 14 Jul 2007) $ */ public class RowSetDynaClass extends JDBCDynaClass implements DynaClass, Serializable { // ----------------------------------------------------- Instance variables /** *

Limits the size of the returned list. The call to * getRows() will return at most limit number of rows. * If less than or equal to 0, does not limit the size of the result. */ protected int limit = -1; /** *

The list of {@link DynaBean}s representing the contents of * the original ResultSet on which this * {@link RowSetDynaClass} was based.

*/ protected List rows = new ArrayList(); // ----------------------------------------------------------- Constructors /** *

Construct a new {@link RowSetDynaClass} for the specified * ResultSet. The property names corresponding * to column names in the result set will be lower cased.

* * @param resultSet The result set to be wrapped * * @exception NullPointerException if resultSet * is null * @exception SQLException if the metadata for this result set * cannot be introspected */ public RowSetDynaClass(ResultSet resultSet) throws SQLException { this(resultSet, true, -1); } /** *

Construct a new {@link RowSetDynaClass} for the specified * ResultSet. The property names corresponding * to column names in the result set will be lower cased.

* * If limit is not less than 0, max limit * number of rows will be copied into the list. * * @param resultSet The result set to be wrapped * @param limit The maximum for the size of the result. * * @exception NullPointerException if resultSet * is null * @exception SQLException if the metadata for this result set * cannot be introspected */ public RowSetDynaClass(ResultSet resultSet, int limit) throws SQLException { this(resultSet, true, limit); } /** *

Construct a new {@link RowSetDynaClass} for the specified * ResultSet. The property names corresponding * to the column names in the result set will be lower cased or not, * depending on the specified lowerCase value.

* * If limit is not less than 0, max limit * number of rows will be copied into the resultset. * * * @param resultSet The result set to be wrapped * @param lowerCase Should property names be lower cased? * * @exception NullPointerException if resultSet * is null * @exception SQLException if the metadata for this result set * cannot be introspected */ public RowSetDynaClass(ResultSet resultSet, boolean lowerCase) throws SQLException { this(resultSet, lowerCase, -1); } /** *

Construct a new {@link RowSetDynaClass} for the specified * ResultSet. The property names corresponding * to the column names in the result set will be lower cased or not, * depending on the specified lowerCase value.

* *

WARNING - If you specify false * for 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.

* * @param resultSet The result set to be wrapped * @param lowerCase Should property names be lower cased? * @param limit Maximum limit for the List of {@link DynaBean} * * @exception NullPointerException if resultSet * is null * @exception SQLException if the metadata for this result set * cannot be introspected */ public RowSetDynaClass(ResultSet resultSet, boolean lowerCase, int limit) throws SQLException { if (resultSet == null) { throw new NullPointerException(); } this.lowerCase = lowerCase; this.limit = limit; introspect(resultSet); copy(resultSet); } /** *

Return a List containing the {@link DynaBean}s that * represent the contents of each Row from the * ResultSet that was the basis of this * {@link RowSetDynaClass} instance. These {@link DynaBean}s are * disconnected from the database itself, so there is no problem with * modifying the contents of the list, or the values of the properties * of these {@link DynaBean}s. However, it is the application's * responsibility to persist any such changes back to the database, * if it so desires.

* * @return A List of {@link DynaBean} instances */ public List getRows() { return (this.rows); } // ------------------------------------------------------ Protected Methods /** *

Copy the column values for each row in the specified * ResultSet into a newly created {@link DynaBean}, and add * this bean to the list of {@link DynaBean}s that will later by * returned by a call to getRows().

* * @param resultSet The ResultSet whose data is to be * copied * * @exception SQLException if an error is encountered copying the data */ protected void copy(ResultSet resultSet) throws SQLException { int cnt = 0; while (resultSet.next() && (limit < 0 || cnt++ < limit) ) { DynaBean bean = createDynaBean(); for (int i = 0; i < properties.length; i++) { String name = properties[i].getName(); Object value = getObject(resultSet, name); bean.set(name, value); } rows.add(bean); } } /** *

Create and return a new {@link DynaBean} instance to be used for * representing a row in the underlying result set.

* * @return A new DynaBean instance */ protected DynaBean createDynaBean() { return (new BasicDynaBean(this)); } }




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