DataExtractor.java

public abstract class DataExtractor implements RowMapper<DataEventMessage> {

    protected ObjectMapper objectMapper;

    private String sql;

    private String schema;

    private JdbcTemplate jdbcTemplate;

    public DataEventMessage extract(final long uniqueId) {
        return jdbcTemplate.query(sql, this, uniqueId);
    }

    public abstract String getPrimaryTable();

    public abstract String getSql();

    @PostConstruct
    public void postConstruct() {
        this.objectMapper = new ObjectMapper().setSerializationInclusion(JsonInclude.Include.NON_NULL);
        this.sql = getSql().replace("<schema>", schema);
    }

    @Autowired
    public DataExtractor setJdbcTemplate(final JdbcTemplate jdbcTemplate) {
        this.jdbcTemplate = jdbcTemplate;
        return this;
    }

    @Autowired
    public DataExtractor setSchema(@Value("${database.schema}") final String schema) {
        this.schema = schema;
        return this;
    }

    public boolean shouldExport() {
        return true;
    }
}

FooExtractor.java

public class FooExtractor extends DataExtractor {

    private static final String SQL = ""
            + " SELECT bar.baz  AS baz,"
            + "        foo.qux  AS qux,"
            + "        foo.quux AS quux"
            + " FROM <schema>.foo foo"
            + "          JOIN <schema>.bar bar ON foo.id = bar.foo_id"
            + " WHERE foo.id = ?";

    @Override
    public String getPrimaryTable() {
        return "foo";
    }

    @Override
    public String getSql() {
        return SQL;
    }

    @Override
    public DataEventMessage mapRow(final ResultSet rs, final int rowNum) throws SQLException {
        var message = new DataEventMessage();
        message.setBaz(rs.getString("baz"))
               .setQux(rs.getString("qux"))
               .setQuux(rs.getString("quux"));

        return message;
    }
}