? Restrictions 类的作用是什么?
? Criteria 接口没有 iterate() 方法。
? Criteria 查询如何对查询结果排序、分页?
? Criteria 查询如何实现关联?
? Criteria 查询如何实现分组聚合?
? DetachedCriteria 有什么作用?
用代码告诉你:
package Test; import java.text.SimpleDateFormat; import java.util.Iterator; import java.util.List; import org.hibernate.Criteria; import org.hibernate.Session; import org.hibernate.criterion.DetachedCriteria; import org.hibernate.criterion.MatchMode; import org.hibernate.criterion.Order; import org.hibernate.criterion.ProjectionList; import org.hibernate.criterion.Projections; import org.hibernate.criterion.Property; import org.hibernate.criterion.Restrictions; import org.junit.Test; import entity.Dept; import entity.Emp; import entity.QueryCondition; import util.HibernateSessionFactory; //criteria查询 public class TestCriteria { @Test public void Test1(){ Session session =HibernateSessionFactory.getSession(); try { Criteria criteria = session.createCriteria(Emp.class); Iterator<Emp> iter = criteria.list().iterator(); while(iter.hasNext()){ Emp emp=iter.next(); System.out.println(emp.getEname()); } } catch (Exception e) { // TODO: handle exception } } /* 职位是工程师,如:job = ‘engineer’ ?工资大于2000元,如:salary > 2000 ?入职时间在2006年12月31日至2008年12月31日之间 模糊查询的时候可以使用 criteria动态查询 */ @Test public void Test2(){ Session session =HibernateSessionFactory.getSession(); try { Criteria criteria = session.createCriteria(Emp.class); QueryCondition queryCondition=new QueryCondition(); queryCondition.setStartdate(new SimpleDateFormat("yyyy-MM-dd").parse("1980-12-17")); queryCondition.setEnddate(new SimpleDateFormat("yyyy-MM-dd").parse("1987-12-32")); Emp emp =new Emp(); emp.setSal(2000D); //emp.setJob("SALESMAN"); if(queryCondition.getStartdate()!=null){ criteria.add(Restrictions.gt("hiredate",queryCondition.getStartdate() )); } if(queryCondition.getEnddate()!=null){ criteria.add(Restrictions.lt("hiredate",queryCondition.getEnddate() )); } if(emp.getSal()!=null){ criteria.add(Restrictions.gt("sal", 2000D)); } if(emp.getJob()!=null){ criteria.add(Restrictions.eq("job", "SALESMAN")); } List<Emp> emplist = criteria.list(); for (Emp emp1 : emplist) { System.out.println(emp1.getJob()+"\t"+emp1.getSal()+"\t"+emp1.getHiredate()); } } catch (Exception e) { // TODO: handle exception } } /* 职位是工程师,如:job = ‘engineer’ ?工资大于2000元,如:salary > 2000 ?入职时间在2006年12月31日至2008年12月31日之间 模糊查询的时候可以使用,加上分页 */ @Test public void Test3(){ Session session =HibernateSessionFactory.getSession(); try { Criteria criteria = session.createCriteria(Emp.class); QueryCondition queryCondition=new QueryCondition(); queryCondition.setStartdate(new SimpleDateFormat("yyyy-MM-dd").parse("1980-12-17")); queryCondition.setEnddate(new SimpleDateFormat("yyyy-MM-dd").parse("1987-12-32")); Emp emp =new Emp(); emp.setSal(2000D); //emp.setJob("SALESMAN"); if(queryCondition.getStartdate()!=null){ criteria.add(Restrictions.gt("hiredate",queryCondition.getStartdate() )); } if(queryCondition.getEnddate()!=null){ criteria.add(Restrictions.lt("hiredate",queryCondition.getEnddate() )); } if(emp.getSal()!=null){ criteria.add(Restrictions.gt("sal", 2000D)); } if(emp.getJob()!=null){ criteria.add(Restrictions.eq("job", "SALESMAN")); } //设置每页显示多少条 int pageSize=2; int pageNo=2;//当前第几页 //得出总页数 int totalCount =(Integer) criteria.setProjection(Projections.rowCount()).uniqueResult(); int totalPage = totalCount%pageSize==0?totalCount/pageSize:totalCount/pageSize+1; criteria.setProjection(null); criteria.setFirstResult(pageNo);//第几页的查询 criteria.setMaxResults(pageSize);//最多显示几条 List<Emp> emplist = criteria.list(); for (Emp emp1 : emplist) { System.out.println(emp1.getJob()+"\t"+emp1.getSal()+"\t"+emp1.getHiredate()); } } catch (Exception e) { // TODO: handle exception } } /*criteria排序 * 按员工工资降序排列 * */ @Test public void test4(){ Session session =HibernateSessionFactory.getSession(); try { Criteria criteria = session.createCriteria(Emp.class,"e"); criteria.add(Restrictions.gt("sal", 2000D)); //criteria.addOrder(Order.asc("sal"));//按工资升序 criteria.addOrder(Order.desc("empno"));//按工号降序 List<Emp> emplist = criteria.list(); for (Emp emp : emplist) { System.out.println(emp.getEmpno()+"\t"+emp.getEname()+"\t"+emp.getSal()); } } catch (Exception e) { e.printStackTrace(); } } /*查询工资最高的员工*/ @Test public void test5(){ Session session =HibernateSessionFactory.getSession(); try { Object obj=session.createCriteria(Emp.class,"e") .add(Restrictions.isNotEmpty("e.sal")) .addOrder(Order.desc("e.sal")) .setMaxResults(1) .uniqueResult(); System.out.println(obj.toString()); } catch (Exception e) { e.printStackTrace(); } } /*联合查询 * * MatchMode.START:字符串在最前面的位置.相当于"like ‘key%‘" MatchMode.END:字符串在最后面的位置.相当于"like ‘%key‘" MatchMode.ANYWHERE:字符串在中间匹配.相当于"like ‘%key%‘" MatchMode.EXACT:字符串精确匹配.相当于"like ‘key‘" * */ @SuppressWarnings("unchecked") @Test public void test6(){ Session session =HibernateSessionFactory.getSession(); try { List<Emp> emplist=session.createCriteria(Emp.class,"e") .add(Restrictions.ilike("e.ename", "A",MatchMode.ANYWHERE)) .createAlias("dept", "d").add(Restrictions.eq("d.dname", "SALES")).list(); for (Emp emp : emplist) { System.out.println(emp.getEname()+"\t"+emp.getDept().getDname()); } } catch (Exception e) { e.printStackTrace(); } } /** * 查询部门名称 * 投影查询:属性查询 */ @SuppressWarnings("unchecked") @Test public void test7(){ Session session =HibernateSessionFactory.getSession(); try { List<String> deptlist = session.createCriteria(Dept.class).setProjection(Property.forName("dname")).list(); for (String string : deptlist) { System.out.println(string); } } catch (Exception e) { e.printStackTrace(); } } /** * 查询部门名称 * 投影查询:查询员工姓名、工资和部门 */ @SuppressWarnings("unchecked") @Test public void test8(){ Session session =HibernateSessionFactory.getSession(); try { List<Object[]> deptlist = session.createCriteria(Emp.class,"e") .createAlias("e.dept", "d") .setProjection(Projections.projectionList() .add(Property.forName("e.ename")) .add(Property.forName("e.sal")) .add(Property.forName("d.dname"))).list(); System.out.println(deptlist.size()); for (Object[] obj : deptlist) { System.out.println(obj[0] + ","+obj[1]+","+obj[2]); } } catch (Exception e) { e.printStackTrace(); } } /** * 统计各个部门的平均工资、最高工资、最低工资 */ @SuppressWarnings("unchecked") @Test public void test9(){ Session session =HibernateSessionFactory.getSession(); try { List<Object[]> deptlist = session.createCriteria(Emp.class,"e") .createAlias("e.dept", "d") .setProjection(Projections.projectionList() .add(Projections.groupProperty("d.dname")) .add(Projections.avg("e.sal")) .add(Projections.max("e.sal")) .add(Projections.min("e.sal"))).list(); System.out.println("各部门平均工资、最高工资、最低工资是:============"); for (Object[] obj : deptlist) { System.out.println(obj[0] + ","+obj[1]+","+obj[2]); } } catch (Exception e) { e.printStackTrace(); } } /** * 使用DetachedCriteria查询财务部的姓名包括“a”的员工 * DetachedCriteria 和 Criteria 功能类似 ?Criteria是由Session对象创建的, DetachedCriteria创建时不需要Session对象 ?可以把DetachedCriteria作为方法参数传递来构造查 询条件 */ @SuppressWarnings("unchecked") @Test public void test10(){ Session session =HibernateSessionFactory.getSession(); try { DetachedCriteria detachedCriteria=DetachedCriteria.forClass(Emp.class,"e") .createAlias("e.dept", "d") .add(Restrictions.eq("d.dname", "SALES")) .add(Restrictions.ilike("e.ename", "a",MatchMode.ANYWHERE)); List<Emp> list = detachedCriteria.getExecutableCriteria(session).list(); System.out.println("使用DetachedCriteria查询财务部的姓名包括“a”的员工=============="); for (Emp emp : list) { System.out.println(emp.getEname()+"\t"+emp.getDept().getDname()); } } catch (Exception e) { e.printStackTrace(); } } /** * 使用DetachedCriteria作为查询条件,查询工资高于平均工资的员工 */ @SuppressWarnings("unchecked") @Test public void test11(){ Session session =HibernateSessionFactory.getSession(); try { DetachedCriteria avgsal=DetachedCriteria.forClass(Emp.class,"e") .setProjection(Projections.avg("e.sal")); List<Emp> list = session.createCriteria(Emp.class,"e") .createAlias("e.dept", "d") .add(Property.forName("e.sal").gt(avgsal)).list(); for (Emp emp : list) { System.out.println(emp.getEname()+"\t"+emp.getSal()); } } catch (Exception e) { e.printStackTrace(); } } }
时间: 2024-10-07 05:22:11