我想從 Rest API 端點返回 JSON 作為帶有值的鍵。例子： { "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} }如何添加密鑰？我想應該是這樣的：List<String<List<TopTerminalsDTO>>>>你能給我一些代碼示例嗎？清理最終代碼的最新嘗試：@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);}
2 回答
滄海一幻覺
TA貢獻1824條經驗 獲得超5個贊
在您的 JSON 之后，testDate()應該返回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;
當然，將休息方法的響應類型更改為ResponseEntity<Map<String, TopTerminalsDTO>>
慕仙森
TA貢獻1827條經驗 獲得超8個贊
這就是 Javascript 的dictionary樣子。
在 Java 中，正確的表示是Map<String, TopTerminalDto>.
假設您有一個有序列表，并且您想返回一個Map帶有生成的鍵的列表terminal{index}。
final List<TopTerminalDto> list = ...
final Map<String, TopTerminalDto> map =
IntStream.range(0, list.size())
.boxed()
.collect(toMap(i -> "terminal" + i, i -> list.get(i)));
Spring 端點將變為：
@GetMapping("terminals")
Map<String, TopTerminalDto> getTopTerminalVolumes() { ... }
在ResponseEntitySpring 中不是強制性的。
記住盡可能通過Stream(s) 工作，以產生沒有中間臨時狀態的結果。
附加示例：
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
}
對于與終端關聯的多個值：
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;
}
)
));
您可以通過提取收集器來清理代碼。
final Collector<Integer, List<TopTerminalDto>, List<TopTerminalDto>> terminalsCollector =
Collector.of(
ArrayList::new,
(terminals, p) -> terminals.add(toDto(p)),
(accumulator, terminals) -> {
accumulator.addAll(terminals);
return accumulator;
}
)
final Map<Integer, List<TopTerminalDto>> map =
list.stream()
.filter(p -> p.getTerminal() != null)
.collect(groupingBy(p -> p.getTerminal(), terminalsCollector));
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