Spring provides a simpler RowCallbackHandler interface when there is no return object. It is used to stream rows to a file, converting the rows to XML, and filtering them before adding to a collection. But filtering in SQL is much more efficient, and is faster than the JPA equivalent for big queries. Let's look at the following example:

    public interface RowCallbackHandler { 
      void processRow(ResultSet rs) throws SQLException; 
    } 

Example for using a RowCallbackHandler

The following code is an example of a RowCallbackHandler in the application:

    package com.packt.patterninspring.chapter7.bankapp.callbacks; 
    import java.sql.ResultSet; 
    import java.sql.SQLException; 
    import org.springframework.jdbc.core.RowCallbackHandler; 
    public class AccountReportWriter implements RowCallbackHandler { 
      public void processRow(ResultSet resultSet) throws SQLException { 
        // parse current row from ResultSet and stream to output 
        //write flat file, XML 
      } 
    } 

In preceding code, we have created a RowCallbackHandler implementation; the AccountReportWriter class implements this interface to process the result set returned from the database. Let's see the following code how to use AccountReportWriter call back class:

    @Override 
    public void generateReport(Writer out, String branchName) { 
      String sql = "SELECT * FROM Account WHERE branchName = "+
       branchName; 
      jdbcTemplate.query(sql, new AccountReportWriter()); 
    } 

RowCallbackHandler is the best choice when no value should be returned from the callback method for each row, especially for large queries.