hibernate-criteria查询(二)

 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-1)*pageSize);//从第几条查询
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();
}
}
}