使用动态调用作为jpa调用的条件

Question

In the following code we get the data from specific entity (Pet). Can I use this code to get dynamically any entity (instead of pet use customer ,order etc)

CriteriaQuery<Pet> cq = cb.createQuery(Pet.class);
Root<Pet> pet = cq.from(Pet.class);
cq.where(cb.equal(pet.get("name"), "Fido"));
TypedQuery<Pet> q = em.createQuery(cq);
List<Pet> results = q.getResultList();

Answer 1

Yes, of course:

public <T> List<T> getEntitiesNamedFido(Class<T> clazz) {
    CriteriaQuery<T> cq = cb.createQuery(clazz);
    Root<T> root = cq.from(clazz);
    cq.where(cb.equal(root.get("name"), "Fido"));
    TypedQuery<T> q = em.createQuery(cq);
    List<T> results = q.getResultList();
}

Now pass any entity class having a persistent "name" property, and you'll get a list of the entity instances named Fido.

Answer 2

在函数上使用模板并通过参数传递类类型，参数名称和值。