spring data jpa 代码实现 增删改查

package cn.kgc.test;

import cn.kgc.pojo.Customer;
import org.junit.*;

import javax.persistence.*;
import java.util.List;

public class CustomerTest {

    private EntityManager entityManager;

    @Before
    public void init(){
        EntityManagerFactory factory = Persistence.createEntityManagerFactory("myjpa");
        entityManager=factory.createEntityManager();
    }
    //添加信息      persist
    @Test
    public void addFirst(){
        EntityTransaction transaction = entityManager.getTransaction();
        transaction.begin();
        for(int i=0;i<10;i++){
            Customer customer = new Customer();
            customer.setCstName("大神"+i);
            customer.setCstAddress("懒人中心"+i);
            customer.setCstLevel("vip");
            entityManager.persist(customer);
        }
        transaction.commit();
        entityManager.close();
    }

    //删除信息        remove
    @Test
    public void deleteTest(){
        EntityTransaction transaction = entityManager.getTransaction();
        transaction.begin();
        Customer customer = entityManager.find(Customer.class, 2l);
        entityManager.remove(customer);
        transaction.commit();
        entityManager.close();
    }

    //修改信息           merge
    @Test
    public void updateTest(){
        EntityTransaction transaction = entityManager.getTransaction();
        transaction.begin();
        Customer customer = entityManager.find(Customer.class, 3l);
        customer.setCstName("小小");
        customer.setCstAddress("北京");
        customer.setCstLevel("svip");
        entityManager.merge(customer);
        transaction.commit();
        entityManager.close();
    }

    //根据ID查询   find  getReference
    @Test
    public void findByIdTest(){
        EntityTransaction transaction = entityManager.getTransaction();
        transaction.begin();
        Customer customer = entityManager.find(Customer.class, 3l);
        System.out.println(customer);
        transaction.commit();
        entityManager.close();
    }
    @Test
    public void findByIdTest2(){
        EntityTransaction transaction = entityManager.getTransaction();
        transaction.begin();
        Customer customer = entityManager.getReference(Customer.class, 3l);
        System.out.println(customer);
        transaction.commit();
        entityManager.close();
    }

    //查询所有
    @Test
    public void findAllTest(){
        EntityTransaction transaction = entityManager.getTransaction();
        transaction.begin();
        Query query = entityManager.createQuery("from Customer");
        List<Customer> resultList = query.getResultList();
        for(Customer customer:resultList){
            System.out.println(customer);
        }
        entityManager.close();
    }

    //分页查询
    @Test
    public void findPageTest(){
        EntityTransaction transaction = entityManager.getTransaction();
        transaction.begin();
        Query query = entityManager.createQuery("from Customer");
        query.setFirstResult(0);
        query.setMaxResults(5);
        List<Customer> resultList = query.getResultList();
        for(Customer customer:resultList){
            System.out.println(customer);
        }
        entityManager.close();
    }

    //jpql按ID查询
    @Test
    public void jpqlFindByIdTest(){
        EntityTransaction transaction = entityManager.getTransaction();
        transaction.begin();
        Query query = entityManager.createQuery("from Customer where cstId=?");
        query.setParameter(1,3l);
        Customer singleResult =(Customer) query.getSingleResult();
        System.out.println(singleResult);
        entityManager.close();
    }

    //模糊查询
    @Test
    public void jpqlLikeFind(){
        Query query = entityManager.createQuery("from Customer where  cstName like ? and cstAddress like ?");
        query.setParameter(1,"%神%");
        query.setParameter(2,"%中%");
        List<Customer> resultList = query.getResultList();
        for(Customer customer:resultList){
            System.out.println(customer);
        }
        entityManager.close();
    }

    //排序
    @Test
    public void findByOrder(){
        Query query = entityManager.createQuery("from Customer order by cstId asc");
        List<Customer> resultList = query.getResultList();
        for(Customer customer:resultList){
            System.out.println(customer);
        }
        entityManager.close();
    }

    //函数
    @Test
    public void mathTest(){
        Query query = entityManager.createQuery("select count(*) from Customer");
        Object singleResult = query.getSingleResult();
        System.out.println(singleResult);
        entityManager.close();
    }
}