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RowCountCallbackHandler (Spring Framework API 2.1) - Spring Framework 2.1.0 API 文档英文版

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org.springframework.jdbc.core
Class RowCountCallbackHandler

java.lang.Object
  org.springframework.jdbc.core.RowCountCallbackHandler

All Implemented Interfaces:

RowCallbackHandler

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public class RowCountCallbackHandler
extends 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

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Constructor Summary
RowCountCallbackHandler()

 

Method Summary
int	getColumnCount()           Return the number of columns in this result set.
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(ResultSet rs)           Implementation of ResultSetCallbackHandler.
protected  void	processRow(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

 

Constructor Detail

RowCountCallbackHandler

public RowCountCallbackHandler()

Method Detail

processRow

public final void processRow(ResultSet rs)
                      throws 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:

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)

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processRow

protected void processRow(ResultSet rs,
                          int rowNum)
                   throws 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:

SQLException

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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.

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getColumnNames

public final 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.

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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

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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

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