Question

我想从Rest API端点返回JSON作为带有值的键。示例：

  {
    "terminal 1":
       {"date":"2018-10-06T00:00:00.000+0000","volume":111,"count":1},
    "terminal 2":
       {"date":"2018-11-06T00:00:00.000+0000","volume":122,"count":1}
  }

如何添加密钥？我应该是这样的：

List<String<List<TopTerminalsDTO>>>>

能给我一些代码示例吗？

最新尝试清除最终代码：

@GetMapping("/terminals")
public ResponseEntity<Map<Integer, List<TopTerminalsDTO>>> getTopTerminalsVolumes(
        @RequestParam(value = "start_date", required = true) String start_date,
        @RequestParam(value = "end_date", required = true) String end_date) {

        LocalDateTime start_datel = LocalDateTime.now(Clock.systemUTC());
        LocalDateTime end_datel = LocalDateTime.now(Clock.systemUTC());

        final List<PaymentTransactionsDailyFacts> list = dashboardRepository.top_daily_transactions(start_datel, end_datel);

        final Collector<PaymentTransactionsDailyFacts, List<TopTerminalsDTO>, List<TopTerminalsDTO>> terminalsCollector =
                 Collector.of(
                    ArrayList::new,
                    (terminals, p) -> terminals.add(mapper.toTopTerminalsDTO(p)),
                    (accumulator, terminals) -> {
                       accumulator.addAll(terminals);
                       return accumulator;
                    }
                 );

        final Map<Integer, List<TopTerminalsDTO>> final_map = 
                     list.stream()
                         .filter(p -> p.getTerminal_id() != null)
                         .collect(Collectors.groupingBy(p -> p.getTerminal_id(), terminalsCollector));

    return ResponseEntity.ok(final_map);
}

Answer 1

在您的JSON之后，testDate()应该返回Map<String, TopTerminalsDTO>而不是List。

Map<String, TopTerminalsDTO> result = newHashMap();

for (int i = 0; i <= 10; i++) {

    TopTerminalsDTO ttDto = new TopTerminalsDTO();
    ttDto.setCount(ThreadLocalRandom.current().nextInt(20, 500 + 1));

    LocalDate localDate = LocalDate.now().minus(Period.ofDays((new Random().nextInt(365 * 70))));
    Date date = Date.from(localDate.atStartOfDay(ZoneId.systemDefault()).toInstant());

    ttDto.setDate(date);
    ttDto.setVolume(ThreadLocalRandom.current().nextInt(300, 5000 + 1));

    result.put("terminal "+i, ttDto)
}

return result;

当然，将rest方法的响应类型更改为ResponseEntity<Map<String, TopTerminalsDTO>>

Answer 2

这是Javascript dictionary的样子。
在Java中，正确的表示形式是Map<String, TopTerminalDto>。

假设您有一个已排序列表，并且您想返回包含生成的密钥Map的{{1}}。

terminal{index}

Spring端点将变为：

final List<TopTerminalDto> list = ...
final Map<String, TopTerminalDto> map = 
         IntStream.range(0, list.size())
                  .boxed()
                  .collect(toMap(i -> "terminal" + i, i -> list.get(i)));

@GetMapping("terminals") Map<String, TopTerminalDto> getTopTerminalVolumes() { ... }在春季不是必需的。

请记住通过ResponseEntity（s）尽可能多地工作，以产生没有中间临时状态的结果。

其他示例：

Stream

对于与终端关联的多个值：

final List<PaymentTransactionsDailyFacts> list = 
            dashboardRepository.top_daily_transactions(start_datel, end_datel);

final Map<String, TopTerminalDto> map =
            list.stream()
                .collect(toMap(p -> p.getTerminal(), this::toDto))

// Conversion method
private TopTerminalDto toDto(final PaymentTransactionsDailyFacts p) {
    // Implement conversion to Dto
}

您可以通过提取收集器来清理代码。

final Map<Integer, List<TopTerminalDto>> map = 
             list.stream()
                 .filter(p -> p.getTerminal() != null)
                 .collect(groupingBy(
                     p -> p.getTerminal(),
                     Collector.of(
                            ArrayList::new,
                            (terminals, p) -> terminals.add(toDto(p)),
                            (accumulator, terminals) -> {
                                accumulator.addAll(terminals);
                                return accumulator;
                            }
                     )
             ));

返回带有Rest API中值的键

2 个答案: