org.springframework.jdbc.core
Interface ColumnExtractor

All Known Implementing Classes:

DefaultColumnExtractor

public interface ColumnExtractor

Interface to be implemented by objects that know how to extract columns from a ResultSet and ensure that they are of a given type.

Different drivers and databases may require slightly different implementations.
This is a useful concept, although there is little requirement for it in the framework classes in this package.

Author:

Rod Johnson

Since: May 2, 2001

public Object extractColumn(String columnName, Class requiredType, ResultSet rs)
                      throws java.sql.SQLException

Extract the given column from this row of the given ResultSet, ensuring that the returned object is of the required type. A naive implementation of this might simply call ResultSet.getObject(columnName). Note that if there is a fundamental mismatch between column type and the required Java type, implementing classes are not required to succeed.

Parameters:

columnName - name of the column we want from the ResultSet

requiredType - class of object we must return

rs - ResultSet to extract the column value from

Returns: the value of the specified column in the ResultSet as an instance of the required type

Throws:

SQLException - if there is any problem getting this column value. Implementations of this interface do not need to worry about handling such exceptions; they can assume they will only be called by code that correctly cleans up after any SQLExceptions

public Object extractColumn(int i, Class requiredType, ResultSet rs)
                      throws java.sql.SQLException

Extract the given column from this row of the given ResultSet, ensuring that the returned object is of the required type. Should implement the same conversion as extractColumn(columnName...).

Parameters:

i - index (from 1) of the column we want from the ResultSet

requiredType - class of object we must return

rs - ResultSet to extract the column value from

Returns: the value of the specified column in the ResultSet as an instance of the required type

Throws:

SQLException - if there is any problem getting this column value. Implementations of this interface do not need to worry about handling such exceptions; they can assume they will only be called by code that correctly cleans up after any SQLExceptions