SSH与SSM学习之hibernate21——离线查询

一、离线查询说明

我们在使用查询的时候，都是Service通过传递参数调用Dao相应的查询方法。这样有个问题就是我们的查询方法都是固定的。比如我们通过id查询用户，那么就只能通过id查询用户，不能再通过其他方式查询。这样这个方法写的方法就比较多啦。那么我们想要是实现的就是，Dao 内部只做有一个简单的查询，Service等来指定查询的方法等这样的方式怎么做呢？
这就是我们要使用的离线查询了（DetachedCriteria）。

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二、非离线查询和离线查询示意图

非离线查询

离线查询

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三、代码实例

package com.qwm.hibernate03.c_dc;import com.qwm.hibernate03.domain.Customer;import com.qwm.hibernate03.utils.HibernateUtils;import org.hibernate.Criteria;import org.hibernate.Session;import org.hibernate.Transaction;import org.hibernate.criterion.DetachedCriteria;import org.hibernate.criterion.Restrictions;import org.junit.Test;import java.util.List;/** * @author：qiwenming * @date：2017/9/20 0020   23:28 * @description： * 离线查询实例 */public class Demo {    @Test    public void test1(){        //代表service/web层过来的        DetachedCriteria dc = DetachedCriteria.forClass(Customer.class);        dc.add(Restrictions.eq("id",1L));        //查询        query(dc);    }    /**     * 查询方法     * @param dc     */    public void query(DetachedCriteria dc){        Session session = HibernateUtils.openSession();        Transaction t = session.beginTransaction();        Criteria c = dc.getExecutableCriteria(session);        List list = c.list();        System.out.println(list);        t.commit();        session.close();    }}

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四、结果

Hibernate:     alter table cst_linkman        add constraint FKh9yp1nql5227xxcopuxqx2e7q        foreign key (lkm_cust_id)        references cst_customer (cust_id)Hibernate:     alter table sys_user_role        add constraint FKhh52n8vd4ny9ff4x9fb8v65qx        foreign key (role_id)        references sys_role (role_id)Hibernate:     alter table sys_user_role        add constraint FKb40xxfch70f5qnyfw8yme1n1s        foreign key (user_id)        references sys_user (user_id)Hibernate:     select        this_.cust_id as cust_id1_0_0_,        this_.cust_name as cust_nam2_0_0_,        this_.cust_source as cust_sou3_0_0_,        this_.cust_industry as cust_ind4_0_0_,        this_.cust_level as cust_lev5_0_0_,        this_.cust_linkman as cust_lin6_0_0_,        this_.cust_phone as cust_pho7_0_0_,        this_.cust_mobile as cust_mob8_0_0_     from        cst_customer this_     where        this_.cust_id=?Hibernate:     select        linkmens0_.lkm_cust_id as lkm_cus10_1_0_,        linkmens0_.lkm_id as lkm_id1_1_0_,        linkmens0_.lkm_id as lkm_id1_1_1_,        linkmens0_.lkm_gender as lkm_gend2_1_1_,        linkmens0_.lkm_name as lkm_name3_1_1_,        linkmens0_.lkm_phone as lkm_phon4_1_1_,        linkmens0_.lkm_email as lkm_emai5_1_1_,        linkmens0_.lkm_qq as lkm_qq6_1_1_,        linkmens0_.lkm_mobile as lkm_mobi7_1_1_,        linkmens0_.lkm_memo as lkm_memo8_1_1_,        linkmens0_.lkm_position as lkm_posi9_1_1_,        linkmens0_.lkm_cust_id as lkm_cus10_1_1_     from        cst_linkman linkmens0_     where        linkmens0_.lkm_cust_id=?[Customer{cust_id=1, cust_name='吊毛公司', cust_source='null', cust_industry='null', cust_level='null', cust_linkman='null', cust_phone='null', cust_mobile='null', linkMens=[com.qwm.hibernate03.domain.LinkMan@6034e75d, com.qwm.hibernate03.domain.LinkMan@5e63cad]}]