Commons Beanutils example source code file (ResultSetDynaClass.java)

This example Commons Beanutils source code file (ResultSetDynaClass.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Commons Beanutils tags/keywords

cannot, dynaclass, iterator, jdbc, jdbcdynaclass, nullpointerexception, object, object, resultset, resultset, resultsetdynaclass, resultsetdynaclass, resultsetiterator, sql, sqlexception, sqlexception, util

The Commons Beanutils ResultSetDynaClass.java source code

/*
 * 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 DynaClass for DynaBeans that wrap the
 * <code>java.sql.Row objects of a 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>WARNING - 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>
 *   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.  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
     *  is <code>null
     * @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.  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>WARNING - If you specify 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?
     *
     * @exception NullPointerException if <code>resultSet
     *  is <code>null
     * @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.  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>WARNING - If you specify 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
     *
     * @exception NullPointerException if <code>resultSet
     *  is <code>null
     * @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 ResultSet we are wrapping.

     */
    protected ResultSet resultSet = null;


    // --------------------------------------------------------- Public Methods


    /**
     * <p>Return an 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 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.

     */
    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);
        }
    }
}