Spring批处理读取器中sql查询内部的java调用方法

Question

我有一个枚举，它从性别字符返回性别：

public enum Gender {
        FEMALE('F'), MALE('M');
        private char gender;

        Gender(char gender) {
            this.gender = gender;
        }

        public static Gender getSex(char gender) {
            return Arrays.stream(Gender.values())
                    .filter(s -> s.gender == gender)
                    .findFirst()
                    .orElseThrow(NoSuchElementException::new);
        }
    }

在一份工作中，我有一个带有queryprovider的阅读器，可以从DB中选择sex列（值为F或M）

 ItemReader<UserDTO> userDatabaseReader() {
        JdbcPagingItemReader<UserDTO> reader = new JdbcPagingItemReader<>();
        reader.setDataSource(dataSource);
        reader.setPageSize(100);
        reader.setRowMapper(new BeanPropertyRowMapper<>(UserDTO.class));
        MySqlPagingQueryProvider queryProvider = new MySqlPagingQueryProvider();

        queryProvider.setSelectClause("SELECT u.id, " +
                "u.firstname as firstName, " +
                "u.sex as gender, " +
                "u.eliminated ^ 1 as active");

        queryProvider.setFromClause("FROM users u");
        HashMap<String, Order> sortKeys = new HashMap<>();
        sortKeys.put("u.id", Order.DESCENDING);
        queryProvider.setSortKeys(sortKeys);

        reader.setQueryProvider(queryProvider);
        return reader;

    }

我有性别枚举字段的UserDTO。 如何从调用getSex()方法的列char中获取性别枚举，并将其作为枚举传递给UserDTO

Answer 1

可以手动实现行映射器

差不多

class UserDTORowMapper implements RowMapper<UserDTO> {

    @Override
    public UserDTO mapRow(ResultSet rs, int rowNum) throws SQLException {

        return new UserDTO(rs.getString("id"), 
                           rs.getString("firstName"), 
                           GenderEnum.valueOf(rs.getString("gender")));
    }
}

而不是你的读者

 ItemReader<UserDTO> userDatabaseReader() {
        JdbcPagingItemReader<UserDTO> reader = new JdbcPagingItemReader<>();
        reader.setDataSource(dataSource);
        reader.setPageSize(100);
        reader.setRowMapper(new UserDTORowMapper());
        MySqlPagingQueryProvider queryProvider = new MySqlPagingQueryProvider();

        queryProvider.setSelectClause("SELECT u.id, " +
                "u.firstname as firstName, " +
                "u.sex as gender, " +
                "u.eliminated ^ 1 as active");

        queryProvider.setFromClause("FROM users u");
        HashMap<String, Order> sortKeys = new HashMap<>();
        sortKeys.put("u.id", Order.DESCENDING);
        queryProvider.setSortKeys(sortKeys);

        reader.setQueryProvider(queryProvider);
        return reader;

    }

代码多一点，但你有更多的灵活性