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/*
* Copyright 2001-2004 The Apache Software Foundation.
*
* 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 net.admin4j.deps.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: 1.9 $ $Date: 2004/02/28 13:18:34 $
*/
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?
*
* @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.
*/
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();
bean.set(name, resultSet.getObject(name));
}
rows.add(bean);
}
}
/**
* Create and return a new {@link DynaBean} instance to be used for
* representing a row in the underlying result set.
*/
protected DynaBean createDynaBean() {
return (new BasicDynaBean(this));
}
}