Getting Startedwith pureQuery

13.4.1 Writing a ResultHandler implementation
Chapter 13 – Handlers 269
The ResultHandler interface has the method handle, shown in figure Listing
13.9.
RES handle(ResultSet resultSet);
Listing 13.9 - The handle method in the ResultHandler interface
The parameter to the handle method is a java.sql.ResultSet object. This is the
query result of the SQL statement. Your implementation of the handle method must use
resultSet to create and return the object that you want your annotated or inline method
to return.
As an example, imagine that you wanted an annotated or inline method to return a String
describing the query result. Spaces should separate the values of the columns, and line
breaks should separate the rows. This would probably not be a very useful way to return a
query result, but we are using this just as a simple example. Listing 13.10 shows how you
could implement such a handler.
import java.sql.ResultSet;
import java.sql.SQLException;
import com.ibm.pdq.runtime.handlers.ResultHandler;
public class SimpleStringResultHandler implements ResultHandler
{
public String handle (ResultSet resultSet)
{
StringBuilder result = new StringBuilder ();
try {
int columns = resultSet.getMetaData ().getColumnCount ();
while (resultSet.next ()) {
for (int i = 0; i < columns; i++) {
result.append (resultSet.getString (i) + " ");
}
result.append ("\n");
}
}
catch (SQLException e) {
throw new RuntimeException ("An error occurred while processing the
query result.", e);
}
return result.toString ();
}
}
Listing 13.10 - An example implementation of ResultHandler