JPA2.0 条件查询

 

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