JPA动态查询之QBE查询

最新推荐文章于 2025-06-11 09:57:40 发布

原创最新推荐文章于 2025-06-11 09:57:40 发布 · 532 阅读

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本文深入探讨了Java Persistence API (JPA) 中的Query By Example (QBE) 动态查询机制。QBE允许开发者通过实例化一个实体类并设置其属性来构建查询，从而实现灵活的数据过滤。通过这种方式，可以轻松地处理不同条件的查询需求，而无需编写复杂的 JPQL 或 Criteria 查询。文中将解释QBE的工作原理，并提供示例展示如何在实际应用中使用QBE进行动态查询。

public Map<String, Object> getAssetInventory(AssetInventoryDto dto, PageableDto pageableDto) {
		Pageable pageable = PageRequest.of(pageableDto.getPage() - 1, pageableDto.getSize(), Sort.Direction.DESC,
				"createTimestamp");
		AssetInventoryModel assetInventoryModel = new AssetInventoryModel();
		UserInfoDto userInfoDto = ((SpringSecureUserInfo) MineSecureUtility.currentUser()).getUserInfo();
		assetInventoryModel.setCreateId(userInfoDto.getId());
		//Sort.Order order = new Sort.Order(Sort.Direction.DESC, "").nullsFirst();//空值放前面
		ExampleMatcher matcher = ExampleMatcher.matching().withIgnorePaths("inventoryLoss").withIgnorePaths("quantity")
				.withIgnorePaths("inventoryProfit")// 忽略属性：是否关注。因为是基本类型，需要忽略掉
				.withMatcher("inventoryRunningNum", GenericPropertyMatchers.contains())// 全部模糊查询，即%{inventoryRunningNum}%
				.withMatcher("inventoryName", GenericPropertyMatchers.contains());

		if (!VGUtility.isEmpty(dto.getInventoryRunningNum())) {
			assetInventoryModel.setInventoryRunningNum(dto.getInventoryRunningNum());
		}
		if (!VGUtility.isEmpty(dto.getInventoryName())) {
			assetInventoryModel.setInventoryName(dto.getInventoryName());
		}
		if (!VGUtility.isEmpty(dto.getInventoryStatusStr())) {
			assetInventoryModel
					.setInventoryStatus(INVENTORY_CHECK.values()[Integer.parseInt(dto.getInventoryStatusStr())]);
		}

		Example<AssetInventoryModel> example = Example.of(assetInventoryModel, matcher);
		Page<AssetInventoryModel> list = assetInventoryDao.findAll(example, pageable);
		List<AssetInventoryDto> dtolist = new ArrayList<AssetInventoryDto>();
		list.getContent().stream().forEach(e -> {
			dtolist.add(convertAssetInventoryModelToDto(e));
		});
		Map<String, java.lang.Object> map = new HashMap<String, java.lang.Object>();
		long total = list.getTotalElements();
		map.put("total", total);
		map.put("rows", dtolist);
		return map;
	}