JavaEE6的JPA2.0查询

package com.snailteam.reporting.query;

import java.util.ArrayList;
import java.util.List;

import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.TypedQuery;
import javax.persistence.criteria.CriteriaBuilder;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.ParameterExpression;
import javax.persistence.criteria.Path;
import javax.persistence.criteria.Predicate;
import javax.persistence.criteria.Root;

import com.snailteam.reporting.domain.Product;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import org.springframework.transaction.annotation.Transactional;

import com.snailteam.reporting.domain.Users;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration( { "/META-INF/spring/applicationContext*" })
@Transactional
/**
 * 
 * @author xiaofancn
 * 
 */
public class TestJPAQuery {
	@PersistenceContext
	EntityManager em;

	@Test
	public void testGetUsers(){
		String name="jQuery";
		
		 //创建条件构建对象  
        CriteriaBuilder criteriaBuilder = em.getCriteriaBuilder();  
        //针对Product实体的条件查询  
        CriteriaQuery<Product>  criteriaQuery = criteriaBuilder.createQuery(Product.class);  
        //获取实体Product的属性集 Product.id Product.name  
        Root<Product> productRoot = criteriaQuery.from(Product.class); //HQL
        //获取实体属性
        Path<String> product_name = productRoot.get("name");
        //条件构造
        criteriaQuery.where(criteriaBuilder.equal(product_name,name));//HQL
        
        TypedQuery<Product> queryResult = em.createQuery(criteriaQuery);
        
        System.out.println(queryResult.getResultList());
	}
	@Test
	public void testJpaQuery() {// from Users user where user.name like
								// '%"+name+"'
		// 创建条件查询Builder对象
		CriteriaBuilder queryBuilder = em.getCriteriaBuilder();
		// 针对Users实体的查询
		CriteriaQuery<Users> usersQuery = queryBuilder.createQuery(Users.class);
		// 获取实体Users的属性集 Users.id Users.name
		Root<Users> userRoot = usersQuery.from(Users.class);
		// 条件查询条件List对象
		List<Predicate> criteria = new ArrayList<Predicate>();

		String name = "xiaofancn";
		// 设置查询的属性 select ....
		usersQuery.select(userRoot);//
		if (name != null && !"".equals(name)) {
			// 相当于拼写HQL的Where属性 where a=1 and b=1
			ParameterExpression<String> parameters = queryBuilder.parameter(
					String.class, "name");
			criteria.add(queryBuilder.like(userRoot.<String> get("name"),
					parameters));
			usersQuery.where(criteria.get(0));// 只有一个查询 条件 like name
		}

		// 上面构建一个hql空语句，下面填充属性，如果下面没有填充属性，关于属性的查询就不构造

		TypedQuery<Users> queryResult = em.createQuery(usersQuery);
		if (name != null && !"".equals(name)) {
			// 具体的参数和值
			queryResult.setParameter("name", name + "%");
		}
		queryResult.setFirstResult(0);
		queryResult.setMaxResults(10);
		System.out.println(queryResult.getResultList());

	}

	@Test
	public void testJpaCount() {// from count(*) Users user where user.name like
								// '%"+name+"'
		CriteriaBuilder queryBuilder = em.getCriteriaBuilder();
		CriteriaQuery<Long> usersQuery = queryBuilder.createQuery(Long.class);
		Root<Users> userRoot = usersQuery.from(Users.class);
		List<Predicate> criteria = new ArrayList<Predicate>();
		String name = "1";

		usersQuery.select(queryBuilder.count(userRoot));
		if (name != null && !"".equals(name)) {
			ParameterExpression<String> parameters = queryBuilder.parameter(
					String.class, "name");
			criteria.add(queryBuilder.like(userRoot.<String> get("name"),
					parameters));
			usersQuery.where(criteria.get(0));
		}
		TypedQuery<Long> queryResult = em.createQuery(usersQuery);
		if (name != null && !"".equals(name)) {
			queryResult.setParameter("name", name + "%");
		}
		System.out.println(queryResult.getSingleResult());

	}

	@Test
	public void testJpaIn() {
		String sql = "from Resources r where r.id in :array";
		List<Long> list = new ArrayList<Long>();
		list.add(1l);
		System.out.println(em.createQuery(sql).setParameter("array", list)
				.getResultList());

	}
	

}

http://download.oracle.com/javaee/6/tutorial/doc/gjivm.html

评论

1 楼 qianli 2012-02-07  

为什么entityManager.getCriteriaBuilder()为null呢？获取不到啊。