org.springframework.jdbc.core

Class RowCountCallbackHandler

java.lang.Object

org.springframework.jdbc.core.RowCountCallbackHandler

All Implemented Interfaces:

RowCallbackHandler

public class RowCountCallbackHandler
extends java.lang.Object
implements RowCallbackHandler

Implementation of RowCallbackHandler. Convenient superclass for callback handlers. An instance can only be used once.

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.

A usage example with JdbcTemplate:

JdbcTemplate jdbcTemplate = new JdbcTemplate(dataSource);  // reusable object

 RowCountCallbackHandler countCallback = new RowCountCallbackHandler();  // not reusable
 jdbcTemplate.query("select * from user", countCallback);
 int rowCount = countCallback.getRowCount();

Since:

May 3, 2001

Author:

Rod Johnson

Field Summary

Fields

Modifier and Type	Field and Description
private int	columnCount Columns we've seen so far
private java.lang.String[]	columnNames Indexed from 0.
private int[]	columnTypes Indexed from 0.
private int	rowCount Rows we've seen so far

Constructor Summary

Constructors

Constructor and Description
RowCountCallbackHandler()

Method Summary

Modifier and Type	Method and Description
int	getColumnCount() Return the number of columns in this result set.
java.lang.String[]	getColumnNames() Return the names of the columns.
int[]	getColumnTypes() Return the types of the columns as java.sql.Types constants Valid after processRow is invoked the first time.
int	getRowCount() Return the row count of this ResultSet Only valid after processing is complete
void	processRow(java.sql.ResultSet rs) Implementation of ResultSetCallbackHandler.
protected void	processRow(java.sql.ResultSet rs, int rowNum) Subclasses may override this to perform custom extraction or processing.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

rowCount

private int rowCount

Rows we've seen so far

columnCount

private int columnCount

Columns we've seen so far

columnTypes

private int[] columnTypes

Indexed from 0. Type (as in java.sql.Types) for the columns as returned by ResultSetMetaData object.

columnNames

private java.lang.String[] columnNames

Indexed from 0. Column name as returned by ResultSetMetaData object.

Constructor Detail

RowCountCallbackHandler

public RowCountCallbackHandler()

Method Detail

processRow

public final void processRow(java.sql.ResultSet rs)
                      throws java.sql.SQLException

Implementation of ResultSetCallbackHandler. Work out column size if this is the first row, otherwise just count rows.

Subclasses can perform custom extraction or processing by overriding the processRow(ResultSet, int) method.

Specified by:

processRow in interface RowCallbackHandler

Parameters:

rs - the ResultSet to process (pre-initialized for the current row)

Throws:

java.sql.SQLException - if a SQLException is encountered getting column values (that is, there's no need to catch SQLException)

See Also:

processRow(java.sql.ResultSet, int)

processRow

protected void processRow(java.sql.ResultSet rs,
              int rowNum)
                   throws java.sql.SQLException

Subclasses may override this to perform custom extraction or processing. This class's implementation does nothing.

Parameters:

rs - ResultSet to extract data from. This method is invoked for each row

rowNum - number of the current row (starting from 0)

Throws:

java.sql.SQLException

getColumnTypes

public final int[] getColumnTypes()

Return the types of the columns as java.sql.Types constants Valid after processRow is invoked the first time.

Returns:

the types of the columns as java.sql.Types constants. Indexed from 0 to n-1.

getColumnNames

public final java.lang.String[] getColumnNames()

Return the names of the columns. Valid after processRow is invoked the first time.

Returns:

the names of the columns. Indexed from 0 to n-1.

getRowCount

public final int getRowCount()

Return the row count of this ResultSet Only valid after processing is complete

Returns:

the number of rows in this ResultSet

getColumnCount

public final int getColumnCount()

Return the number of columns in this result set. Valid once we've seen the first row, so subclasses can use it during processing

Returns:

the number of columns in this result set