hibernate @Formula

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有时我们如果想要查询某些不在该表的字段，我们可以不用hql来实现，hibernate为我们提供了@Formula这个注解，通过这个注解我们可以达到我们想要的结果，代码如下：
package com.cmh.beans;

import javax.persistence.*;import org.hibernate.annotations.Formula;  /**  * @ClassName: TestFormula.java  *  * @Description: Hibernate @Formula注解  *  * @author GERRARD  *  * @date 2015年1月27日下午2:06:03  *   */  @Entity  @Table(name = "test_formula")  public class TestFormula {      /**      * 用户ID      */      private String userId;      /**      * 性别ID      */      private String sex;      /**      * 虚拟字段：根据userId从user_info表获取中文名      */      private String userName;      /**      * 虚拟字段：根据sex从code_list表获取对应汉字值      */      private String sexValue;      public TestFormula() {      }      public TestFormula(String userId, String sex) {          this.userId = userId;          this.sex = sex;      }      public int id;    @Column(name = "user_id", length = 25)      public String getUserId() {          return userId;      }      public void setUserId(String userId) {          this.userId = userId;      }      @Column(name = "sex", length = 3)      public String getSex() {          return sex;      }      public void setSex(String sex) {          this.sex = sex;      }      @Formula("(select t.user_name from user_info t where t.user_id = user_id)")      public String getUserName() {          return userName;      }      public void setUserName(String userName) {          this.userName = userName;      }      public String getSexValue() {          return sexValue;      }    @Id    @GeneratedValue    public int getId() {        return id;    }    public void setId(int id) {        this.id = id;    }    public void setSexValue(String sexValue) {        this.sexValue = sexValue;      }  }

我们的junit如下：

package com.cmh.test;import com.cmh.Application;import com.cmh.beans.Girls;import com.cmh.beans.TestFormula;import com.cmh.dao.UserDao;import org.hibernate.SessionFactory;import org.hibernate.cfg.Configuration;import org.hibernate.service.ServiceRegistry;import org.junit.Test;import org.junit.runner.RunWith;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.boot.test.SpringApplicationConfiguration;import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;import javax.persistence.EntityManager;import org.springframework.transaction.annotation.Transactional;import java.util.Iterator;import java.util.List;import java.util.Set;/** * Created by mianhai on 2017/2/15. */@RunWith(SpringJUnit4ClassRunner.class) // SpringJUnit支持，由此引入Spring-Test框架支持！@SpringApplicationConfiguration(classes = Application.class)public class MyTest {    @Autowired    private UserDao userDao;    @Autowired    private EntityManager en;    @Test    @Transactional    public void mytest(){        List< TestFormula> girl = (List< TestFormula>)en.createQuery("select t from TestFormula t").getResultList();        Iterator it = girl.iterator();        while (it.hasNext()){            it.next();        }    }}

运行结果

Hibernate: select testformul0_.id as id1_3_, testformul0_.sex as sex2_3_, testformul0_.sex_value as sex_valu3_3_, testformul0_.user_id as user_id4_3_, (select t.user_name from user_info t where t.user_id = testformul0_.user_id) as formula0_ from test_formula testformul0_

注意，这里面@Formula中的为sql，非hql

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