标签：between birt 注解 ble object lis hda executor type
当Repository接口继承了JpaSpecificationExecutor后，我们就可以使用如下接口进行分页查询：
/** * Returns a {@link Page} of entities matching the given {@link Specification}. * * @param spec can be {@literal null}. * @param pageable must not be {@literal null}. * @return never {@literal null}. */ Page<T> findAll(@Nullable Specification<T> spec, Pageable pageable);
结合jpa-spec可以很容易构造出Specification:
jpa-spec github地址:https://github.com/wenhao/jpa-spec
public Page<Person> findAll(SearchRequest request) { Specification<Person> specification = Specifications.<Person>and() .eq(StringUtils.isNotBlank(request.getName()), "name", request.getName()) .gt(Objects.nonNull(request.getAge()), "age", 18) .between("birthday", new Date(), new Date()) .like("nickName", "%og%", "%me") .build(); return personRepository.findAll(specification, new PageRequest(0, 15)); }
单表查询确实很简单，但对复杂查询，就复杂上些了：
public List<Phone> findAll(SearchRequest request) { Specification<Phone> specification = Specifications.<Phone>and() .eq(StringUtils.isNotBlank(request.getBrand()), "brand", "HuaWei") .eq(StringUtils.isNotBlank(request.getPersonName()), "person.name", "Jack") .build(); return phoneRepository.findAll(specification); }
这里主表是phone，使用了person的name做条件,使用方法是person.name。
jpa-spec内部会分析person.name，如下代码：
public From getRoot(String property, Root<T> root) { if (property.contains(".")) { String joinProperty = StringUtils.split(property, ".")[0]; return root.join(joinProperty, JoinType.LEFT); } else { return root; } }
就可看到它用了root.join，那就有一个问题，如果有两个person字段的条件，那就要再join一次，就会生成这样的sql:
select * from phone left outer join person on XX=XX left outer join person XX=XX.
这样肯定不满足需求。这应该也是jpa-spec的一个bug吧
为了解决这个问题，可以使用它提供的另一种方式查询：
public List<Phone> findAll(SearchRequest request) { Specification<Person> specification = Specifications.<Person>and() .between("age", 10, 35) .predicate(StringUtils.isNotBlank(jack.getName()), ((root, query, cb) -> { Join address = root.join("addresses", JoinType.LEFT); return cb.equal(address.get("street"), "Chengdu"); })) .build(); return phoneRepository.findAll(specification); }
这要就可以解决大多数情况了，除了分页
看下正常的单表分页+排序查询：
public Page<Person> findAll(SearchRequest request) { Specification<Person> specification = Specifications.<Person>and() .eq(StringUtils.isNotBlank(request.getName()), "name", request.getName()) .gt("age", 18) .between("birthday", new Date(), new Date()) .like("nickName", "%og%") .build(); Sort sort = Sorts.builder() .desc(StringUtils.isNotBlank(request.getName()), "name") .asc("birthday") .build(); return personRepository.findAll(specification, new PageRequest(0, 15, sort)); }
如果在此基础上增加关联，如下代码：
public Page<Person> findAll(SearchRequest request) { Specification<Person> specification = Specifications.<Person>and() .predicate(StringUtils.isNotBlank(jack.getName()), ((root, query, cb) -> { Join address = root.join("addresses", JoinType.LEFT); return cb.equal(address.get("street"), "Chengdu"); })) .eq(StringUtils.isNotBlank(request.getName()), "name", request.getName()) .gt("age", 18) .between("birthday", new Date(), new Date()) .like("nickName", "%og%") .build(); Sort sort = Sorts.builder() .desc(StringUtils.isNotBlank(request.getName()), "name") .asc("birthday") .build(); return personRepository.findAll(specification, new PageRequest(0, 15, sort)); }
就会发现addresses的延迟加载失效，生成很多查询addresses的语句，解决方案如下：
public Page<Person> findAll(SearchRequest request) { Specification<Person> specification = Specifications.<Person>and() .predicate(StringUtils.isNotBlank(jack.getName()), ((root, query, cb) -> { Join address; if (Long.class != query.getResultType()) { address = (Join) root.fetch("addresses", JoinType.LEFT); } else { address = root.join("addresses", JoinType.LEFT); } return cb.equal(address.get("street"), "Chengdu"); })) .eq(StringUtils.isNotBlank(request.getName()), "name", request.getName()) .gt("age", 18) .between("birthday", new Date(), new Date()) .like("nickName", "%og%") .build(); Sort sort = Sorts.builder() .desc(StringUtils.isNotBlank(request.getName()), "name") .asc("birthday") .build(); return personRepository.findAll(specification, new PageRequest(0, 15, sort)); }
至此，用Specification查询就应该够用了，再配合JpaRepository （SimpleJpaRepository）提供的方法 和@Query注解方法，和criteria api查询，这四种JPA查询就可以解决大多数应用问题了。
spring data jpa Specification 复杂查询+分页查询
标签：between birt 注解 ble object lis hda executor type
原文地址：https://www.cnblogs.com/hankuikui/p/11414316.html
