具有多个参数的JPA Criteria API

概念是构造javax.persistence.Predicate数组，该数组仅包含我们要使用的谓词：

要查询的示例实体：

@Entitypublic class A {    @Id private Long id;        String someAttribute;    String someOtherAttribute;    ...}

查询本身：

    //some parameters to your method    String param1 = "1";    String paramNull = null;    CriteriaBuilder qb = em.getCriteriaBuilder();    CriteriaQuery cq = qb.createQuery();    Root<A> customer = cq.from(A.class);    //Constructing list of parameters    List<Predicate> predicates = new ArrayList<Predicate>();    //Adding predicates in case of parameter not being null    if (param1 != null) {        predicates.add(     qb.equal(customer.get("someAttribute"), param1));    }    if (paramNull != null) {        predicates.add(     qb.equal(customer.get("someOtherAttribute"), paramNull));    }    //query itself    cq.select(customer) .where(predicates.toArray(new Predicate[]{}));    //execute query and do something with result    em.createQuery(cq).getResultList();