[Hibernate] 通过 properties 类和 hql 语句进行动态查询

Posted 2020-11-20 zZ

//需要保证Emp和EmpProperties中的setter和getter以及属性以及 参数占位符(:eName) 的一致
//动态查询
    @Test
    public void test4(){
        EmpProperties ep=new EmpProperties();
        //set query conditions
        ep.seteName("%A%");
        ep.setStartDate(new Date(383155200000L));
        ep.setEndDate(new Date());
        ep.setJob("CLERK");
        
        //1.obtain org.hibernate.Session object.
        Session ss=HibernateUtil.getSession();
        
        //2.hql statement: s
        StringBuffer hql=new StringBuffer("from Emp e where 1=1 ");
        //3.判断EmpProperties总属性是否为null
        if(ep.geteName()!=null){
            hql.append(" and e.eName like :eName ");//e.eName和Emp中的属性保持一致|:eName和EmpProperties中的属性保持一致
        }
        if(ep.getStartDate()!=null){
            hql.append(" and e.hireDate>=:startDate  ");
        }
        if(ep.getEndDate()!=null){
            hql.append(" and e.hireDate<=:endDate ");
        }
        if(ep.getJob()!=null){
            hql.append(" and e.job=:job");
        }
        
        //执行hql语句,hql转换为String(使用toString()方法)
        Query qr=ss.createQuery(hql.toString());
        //给hql语句中的参数赋值
        qr.setProperties(ep);

        @SuppressWarnings("unchecked")
        List<Emp> el= qr.list();
        for (Emp emp : el) {
            System.out.println(emp.geteName()+"	"+ emp.getEmpNo());
        }
        System.out.println("查询记录数: "+el.size());
        HibernateUtil.closeResource(ss);
    }