Hibernate内存排序

内存排序
内存排序和数据库排序唯一的不同就是在配置文件中使用sort属性而不是order-by属性
他有三个属性值(unsorted,natural),其中natural指的是按照自然的升序排序，第三个
属性值是我们自己定义 的排序规则类，该规则类通过实现Comparator接口，并且实现
该接口中的Compare方法,在该方法中定义排序规则即可。然后将该自定义的排序规则
的类名作为sort的属性值即可.

具体参考:

Team.java

 

package com.fgh.hibernate;
import java.util.Set;
public class Team {
	private String id;
	private String teamName;
	private Set<Student> students;
	public String getId() {
		return id;
	}
	public void setId(String id) {
		this.id = id;
	}
	public String getTeamName() {
		return teamName;
	}
	public void setTeamName(String teamName) {
		this.teamName = teamName;
	}
	public Set<Student> getStudents() {
		return students;
	}
	public void setStudents(Set<Student> students) {
		this.students = students;
	}
}

Student.java

 

 

package com.fgh.hibernate;
/**
 * 一对一双向关联
 * 
 * @author fgh
 * 
 */
public class Student {
	private String id;
	private String name;
	private String idCard;
	private int age;
	private Team team;
	public Team getTeam() {
		return team;
	}
	public void setTeam(Team team) {
		this.team = team;
	}
	public String getId() {
		return id;
	}
	public void setId(String id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getIdCard() {
		return idCard;
	}
	public void setIdCard(String idCard) {
		this.idCard = idCard;
	}
	public int getAge() {
		return age;
	}
	public void setAge(int age) {
		this.age = age;
	}
}

Team.hbm.xml

 

 

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
	<class name="com.fgh.hibernate.Team" table="team">
		<id name="id" column="id" type="string">
			<generator class="uuid"></generator>
		</id>
		<property name="teamName" column="teamName" type="string"></property>
		<!-- 这里sort属性设置我们自己的排序规则 -->
		<set name="students" lazy="false" cascade="all" inverse="true"
			fetch="select" sort="com.fgh.hibernate.MyComparator">
			<key column="team_id"></key>
			<one-to-many class="com.fgh.hibernate.Student" />
		</set>
	</class>
</hibernate-mapping>

Student.hbm.xml

 

 

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
	<class name="com.fgh.hibernate.Student" table="student">
		<id name="id" column="id" type="string">
			<generator class="uuid"></generator>
			
		</id>
		<property name="name" column="name" type="string"></property>
		<property name="idCard" column="idcard" type="string"></property>
		<property name="age" column="age" type="integer"></property>
		<many-to-one name="team" class="com.fgh.hibernate.Team"
			column="team_id">
		</many-to-one>
	</class>
</hibernate-mapping>

自定义排序规则类：

MyComparator.java

 

package com.fgh.hibernate;
import java.util.Comparator;
/**
 * 自定义排序规则类
 * 
 * @author fgh
 *
 */
public class MyComparator implements Comparator<Student> {
	public int compare(Student s1, Student s2) {
		//如果两个对象相同，不排序
		if (s1 == s2) {
			return 0;
		}
		int result = s1.getIdCard().compareToIgnoreCase(s2.getIdCard());
		//如果cardId不同，按照cardId排序
		if (result != 0) {
			//如果降序 return -result;
			return result;
		}
		//如果cardId相同，按照name排序
		//如果降序 返回负值
		return s1.getName().compareToIgnoreCase(s2.getName());
	}
}

测试类：

 

HIbernateTest.java

 

package com.fgh.hibernate;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
public class HibernateTest {
	private static SessionFactory sessionFactory;
	static {
		try {
			sessionFactory = new Configuration().configure()
					.buildSessionFactory();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
	public static void main(String[] args) {
		// 先执行插入操作 有了数据才可以查询哦
		// ------------begin--------------
		Team team = new Team();
		team.setTeamName("team1");
		team.setStudents(new HashSet<Student>());
		Student student = new Student();
		student.setName("zhangsan");
		student.setIdCard("aa");
		student.setAge(20);
		Student student1 = new Student();
		student1.setName("lisi");
		student1.setIdCard("aa");
		student1.setAge(21);
		Student student2 = new Student();
		student2.setName("wangwu");
		student2.setIdCard("ba");
		student2.setAge(22);
		Student student3 = new Student();
		student3.setName("xiaoqiang");
		student3.setIdCard("bb");
		student3.setAge(23);
		Student student4 = new Student();
		student4.setName("xiaohong");
		student4.setIdCard("dc");
		student4.setAge(24);
		team.getStudents().add(student);
		team.getStudents().add(student1);
		team.getStudents().add(student2);
		team.getStudents().add(student3);
		team.getStudents().add(student4);
		student.setTeam(team);
		student1.setTeam(team);
		student2.setTeam(team);
		student3.setTeam(team);
		student4.setTeam(team);
		// -------------end------------
		Session session = sessionFactory.openSession();
		Transaction tx = null;
		try {
			tx = session.beginTransaction();
			// 查询----bein--------
			Team team2 = (Team) session.get(Team.class,
					"8a8ae4d934b2bfa10134b2bfa4a30001");
			Set<Student> set = team2.getStudents();
			for (Iterator<Student> iterator = set.iterator(); iterator
					.hasNext();) {
				System.out.println(iterator.next().getName());
			}
			// --------------end----------
			// 保存
			// session.save(team);
			tx.commit();
		} catch (Exception e) {
			e.printStackTrace();
			if (null != tx) {
				tx.rollback();
			}
		} finally {
			session.close();
		}
	}
}

打印sql：

 

 

Hibernate: select team0_.id as id1_0_, team0_.teamName as teamName1_0_ from team team0_ where team0_.id=?
Hibernate: select students0_.team_id as team5_1_, students0_.id as id1_, students0_.id as id0_0_, students0_.name as name0_0_, students0_.idcard as idcard0_0_, students0_.age as age0_0_, students0_.team_id as team5_0_0_ from student students0_ where students0_.team_id=?
lisi
zhangsan
wangwu
xiaoqiang
xiaohong

哦也，完成