java - 可选的 Spring 分页

Question

我是 java 和 spring 的新手。

我想要实现的是带有分页和排序的 api 端点 /tickets。我做到了并且有效。但我还想做的是，如果查询参数中未指定 size 和 page，则返回所有票证的普通列表，因此在 FE 中我可以使用该列表在选择框中。

我尝试做的是在服务外观上实现 getTickets 并返回所有票证列表。但是我没有找到一种方法来检查是否设置了 Pageable，因为它总是返回默认值 (size=20, page=0)

// Controller

@RequestMapping(method = RequestMethod.GET)
public ResponseEntity<Page<TicketListItemResponseModel>> getTickets(Pageable pageable) {
    logger.info("> getTickets");
    Page<TicketListItemResponseModel> tickets = ticketServiceFacade.getTickets(pageable);
    logger.info("< getTickets");
    return new ResponseEntity<>(tickets, HttpStatus.OK);
}

//TicketServiceFacade

public Page<TicketListItemResponseModel> getTickets(Pageable pageable) {
    Page<Ticket> tickets = ticketService.findAll(pageable);
    return tickets.map(new ConverterFromPagesToListItem());
}

public List<TicketListItemResponseModel> getTickets() {
    List<Ticket> tickets = ticketService.findAll();
    return tickets.stream()
            .map(t -> modelMapper.map(t, TicketListItemResponseModel.class))
            .collect(Collectors.toList());
}

也许我完全错了？

Answer 1

如果你像这样构建你的 Controller 方法，你可以通过检查请求参数来管理是否要实现分页:

@Override
public ResponseEntity<Page<TicketListItemResponseModel>> getTickets(
        @RequestParam(value = "page", defaultValue = "0", required = false) int page,
        @RequestParam(value = "count", defaultValue = "10", required = false) int size,
        @RequestParam(value = "order", defaultValue = "ASC", required = false) Sort.Direction direction,
        @RequestParam(value = "sort", defaultValue = "name", required = false) String sortProperty) {
    // here you would check your request params and decide whether or not to do paging and then return what you need to return
}

如果您需要构建一个 PageRequest 以传递到您的服务方法中，您可以像这样手动执行此操作:

new PageRequest(page, size, new Sort(direction, sortProperty));