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/*
* Copyright 2002-2012 the original author or authors.
*
* 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 org.springframework.jdbc.core;
import org.springframework.jdbc.support.JdbcUtils;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
/**
* Implementation of RowCallbackHandler. Convenient superclass for callback handlers.
* An instance can only be used once.
*
* <p>We can either use this on its own (for example, in a test case, to ensure
* that our result sets have valid dimensions), or use it as a superclass
* for callback handlers that actually do something, and will benefit
* from the dimension information it provides.
*
* <p>A usage example with JdbcTemplate:
*
* <pre class="code">JdbcTemplate jdbcTemplate = new JdbcTemplate(dataSource); // reusable object
*
* RowCountCallbackHandler countCallback = new RowCountCallbackHandler(); // not reusable
* jdbcTemplate.query("select * from user", countCallback);
* int rowCount = countCallback.getRowCount();</pre>
*
* @author Rod Johnson
* @since May 3, 2001
*/
public class RowCountCallbackHandler implements RowCallbackHandler {
/** Rows we've seen so far */
private int rowCount;
/** Columns we've seen so far */
private int columnCount;
/**
* Indexed from 0. Type (as in java.sql.Types) for the columns
* as returned by ResultSetMetaData object.
*/
private int[] columnTypes;
/**
* Indexed from 0. Column name as returned by ResultSetMetaData object.
*/
private String[] columnNames;
/**
* Implementation of ResultSetCallbackHandler.
* Work out column size if this is the first row, otherwise just count rows.
* <p>Subclasses can perform custom extraction or processing
* by overriding the {@code processRow(ResultSet, int)} method.
* @see #processRow(java.sql.ResultSet, int)
*/
public final void processRow(ResultSet rs) throws SQLException {
if (this.rowCount == 0) {
ResultSetMetaData rsmd = rs.getMetaData();
this.columnCount = rsmd.getColumnCount();
this.columnTypes = new int[this.columnCount];
this.columnNames = new String[this.columnCount];
for (int i = 0; i < this.columnCount; i++) {
this.columnTypes[i] = rsmd.getColumnType(i + 1);
this.columnNames[i] = JdbcUtils.lookupColumnName(rsmd, i + 1);
}
// could also get column names
}
processRow(rs, this.rowCount++);
}
/**
* Subclasses may override this to perform custom extraction
* or processing. This class's implementation does nothing.
* @param rs ResultSet to extract data from. This method is
* invoked for each row
* @param rowNum number of the current row (starting from 0)
*/
protected void processRow(ResultSet rs, int rowNum) throws SQLException {
}
/**
* Return the types of the columns as java.sql.Types constants
* Valid after processRow is invoked the first time.
* @return the types of the columns as java.sql.Types constants.
* <b>Indexed from 0 to n-1.</b>
*/
public final int[] getColumnTypes() {
return columnTypes;
}
/**
* Return the names of the columns.
* Valid after processRow is invoked the first time.
* @return the names of the columns.
* <b>Indexed from 0 to n-1.</b>
*/
public final String[] getColumnNames() {
return columnNames;
}
/**
* Return the row count of this ResultSet
* Only valid after processing is complete
* @return the number of rows in this ResultSet
*/
public final int getRowCount() {
return rowCount;
}
/**
* Return the number of columns in this result set.
* Valid once we've seen the first row,
* so subclasses can use it during processing
* @return the number of columns in this result set
*/
public final int getColumnCount() {
return columnCount;
}
}
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