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RowMapper

RowMapper maps each row while reading a ResultSet. You do not need to manage the ResultSet flow—just focus on processing each row.

Example

public class UserRowMapper implements RowMapper<User> {
    public User mapRow(ResultSet rs, int rowNum) throws SQLException {
        User user = new User();
        user.setId(rs.getInt("id"));
        user.setName(rs.getString("name"));
        return user;
    }
}

How to Use

Example: Programmatic API

UserRowMapper userRowMapper = ...
List<User> result = jdbc.queryForList("select * from users", userRowMapper);

Example: Declarative API

@SimpleMapper
public interface UserMapper {
    @Query(value = "select * from users where id > #{id}",
           resultRowMapper = UserRowMapper.class)
    List<User> listUsers(@Param("id") long searchId);
}

Example: Builder

List<User> result = adapter.queryByEntity(User.class)
                           .le(User::getId, 100)        // match IDs <= 100
                           .queryForList(userRowMapper); // use RowMapper for result set

Example: Mapper File

<select id="queryListByAge" resultRowMapper="com.example.dto.UserRowMapper">
    select * from users where age = #{age}
</select>

Built-ins

dbVisitor ships 4 RowMapper implementations; you can extend as needed.

ColumnMapRowMapper

// Convert each row to a Map
String querySql = "select * from users where age > 40";
RowMapper rowMapper = new ColumnMapRowMapper();
List<Map<String, Object>> result = jdbcTemplate.queryForList(querySql, rowMapper);

SingleColumnRowMapper

// Use when the query returns a single column
String querySql = "select name from users where age > 40";
RowMapper rowMapper = new SingleColumnRowMapper();
List<String> result = jdbcTemplate.queryForList(querySql, rowMapper);

BeanMappingRowMapper

// Map rows to beans via object mapping
String querySql = "select * from users where age > 40";
RowMapper rowMapper = new MappingRowMapper<>(TestUser.class);
List<TestUser> result = jdbcTemplate.queryForList(querySql, rowMapper);

MapMappingRowMapper

// Map rows to Map via object mapping
String querySql = "select * from users where age > 40";
RowMapper rowMapper = new MapMappingRowMapper<>(TestUser.class);
List<Map<String, Object>> result = jdbcTemplate.queryForList(querySql, rowMapper);

Tip

Both ColumnMapRowMapper and MapMappingRowMapper return Map, but differ as follows:

• ColumnMapRowMapper handles arbitrary column sets, e.g., select *.
• MapMappingRowMapper uses the entity type from its constructor to decide the maximum columns in the result set, regardless of whether select * is used.