java - 在 Spring Batch Reader 中的 sql 查询中调用方法

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);
        }
    }

在作业中，我有一个带有查询提供程序的读取器，它从数据库中选择列性别(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;

    }

我有带性别枚举字段的 UserDTO。 如何从调用 getSex() 方法的字符列中获取性别枚举，并将其作为枚举传递给 UserDTO？

Answer 1

该方法是在 Job Processor 中处理读取器结果的每一项。我必须在 DTO 中创建名为 sex 的新属性来存储数据库中的 char sex 列，并使用该属性值获取性别枚举列。这里处理器:

@Bean
ItemProcessor<UserDTO, UserDTO> userProcessor() {
    return item -> {
        try {
            item.setGender(UserDTO.Gender.getGender(item.getSex()));
        } catch (Exception ex) {
            log.error("Error trying to process user '{}'", item.getId());
        }
        return item;
    };
}

在查询中:

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