这里列出了和普通hibernate框架query查询不同的地方的方法，其他的查询方式和query查询一致

package test;

import java.util.List;

import javax.persistence.EntityManager;
import javax.persistence.EntityTransaction;
import javax.persistence.Query;

import org.junit.Test;

import bean.Customer;
import utils.JPAUtils;

public class demo2 {
//jpa的查询   JPA方式: 类似query的方式
	@Test
	//全查
	public void t1() {
		EntityManager en = JPAUtils.getEntityManager();
		EntityTransaction tr = en.getTransaction();
		tr.begin();
		Query qr = en.createQuery("from Customer");
		List<Customer> list = qr.getResultList();//类似于query方式的list（）
		for (Customer customer : list) {
			System.out.println(customer);
		}
		tr.commit();
		en.close();
	}
	
	// 条件查
	@Test
	public void t2() {
		EntityManager en = JPAUtils.getEntityManager();
		EntityTransaction tr = en.getTransaction();
		tr.begin();
		Query qr = en.createQuery("from Customer where cust_name like ?");
		qr.setParameter(1, "a%");// hibernate对于占位符?是从0开始 JPA是从1开始
		List<Customer> list = qr.getResultList();
		for (Customer customer : list) {
			System.out.println(customer);
		}
		tr.commit();
		en.close();
	
	}
	// 聚合查
	@Test
	public void t3() {
		EntityManager en = JPAUtils.getEntityManager();
		EntityTransaction tr = en.getTransaction();
		tr.begin();
		Query qr = en.createQuery("select count(*) from Customer where cust_name like ?");
		qr.setParameter(1, "a%");
		Object obj = qr.getSingleResult();// hibernate query中 的 uniqueResult()
		System.out.println(obj);
		
		tr.commit();
		en.close();
	}
	
	
}