详解Spring Data JPA动态条件查询的写法

JpaSpecificationExecutor

public interface CustomerRepository extends CrudRepository<Customer, Long>, JpaSpecificationExecutor { …}

public interface JpaSpecificationExecutor<T> { T findOne(Specification<T> var1); List<T> findAll(Specification<T> var1); Page<T> findAll(Specification<T> var1, Pageable var2); List<T> findAll(Specification<T> var1, Sort var2); long count(Specification<T> var1);}

List<T> findAll(Specification<T> var1);

org.springframework.data.jpa.domain.Specification

Specification specification = new Specification() {   @Override   public Predicate toPredicate(Root root, CriteriaQuery criteriaQuery, CriteriaBuilder criteriaBuilder) {    return null;   }  }

/** * A root type in the from clause. * Query roots always reference entities. * * @param <X> the entity type referenced by the root * @since Java Persistence 2.0 */public interface Root<X> extends From<X, X> {...}

/** * Used to construct criteria queries, compound selections, * expressions, predicates, orderings. * * <p> Note that <code>Predicate</code> is used instead of <code>Expression<Boolean></code> * in this API in order to work around the fact that Java * generics are not compatible with varags. * * @since Java Persistence 2.0 */public interface CriteriaBuilder {...}

criteriaBuilder.lessThan(root.get("createDate"), today)

/**  * Create a conjunction of the given restriction predicates.  * A conjunction of zero predicates is true.  *  * @param restrictions zero or more restriction predicates  *  * @return and predicate  */ Predicate and(Predicate... restrictions);

/**  * Create a disjunction of the given restriction predicates.  * A disjunction of zero predicates is false.  *  * @param restrictions zero or more restriction predicates  *  * @return or predicate  */ Predicate or(Predicate... restrictions);

public List<WeChatGzUserInfoEntity> findByCondition(Date minDate, Date maxDate, String nickname){  List<WeChatGzUserInfoEntity> resultList = null;  Specification querySpecifi = new Specification<WeChatGzUserInfoEntity>() {   @Override   public Predicate toPredicate(Root<WeChatGzUserInfoEntity> root, CriteriaQuery<?> criteriaQuery, CriteriaBuilder criteriaBuilder) {    List<Predicate> predicates = new ArrayList<>();    if(null != minDate){     predicates.add(criteriaBuilder.greaterThan(root.get("subscribeTime"), minDate));    }    if(null != maxDate){     predicates.add(criteriaBuilder.lessThan(root.get("subscribeTime"), maxDate));    }    if(null != nickname){     predicates.add(criteriaBuilder.like(root.get("nickname"), "%"+nickname+"%"));    }    return criteriaBuilder.and(predicates.toArray(new Predicate[predicates.size()]));   }  };  resultList = this.weChatGzUserInfoRepository.findAll(querySpecifi);  return resultList; }