Hibernate数据库查询

数据库查询排序 常用

Team.java

package com.fgh.hibernate;import java.util.HashMap;import java.util.Map;public class Team { private String id; private String name; private Map students = new HashMap(); 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 Map getStudents() { return students; } public void setStudents(Map students) { this.students = students; }}hibernate.cfg.xml

<?xml version='1.0' encoding='UTF-8'?><!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"><!-- Generated by MyEclipse Hibernate Tools. --><hibernate-configuration> <session-factory> <property name="connection.url"> jdbc:mysql://localhost:3306/hibernate </property> <property name="connection.username">root</property> <property name="connection.password">root</property> <property name="connection.driver_class"> com.mysql.jdbc.Driver </property> <property name="dialect"> org.hibernate.dialect.MySQLDialect </property> <property name="show_sql">true</property> <mapping resource="Team.hbm.xml" /> </session-factory></hibernate-configuration>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_map"> <id name="id" column="id" type="string"> <generator class="uuid"></generator> </id> <property name="name" column="name" type="string"></property> <strong><span style="font-size: 18px; color: #ff6666;" mce_style="font-size: 18px; color: #ff6666;"><!-- order-by 指按数据库排序 属性值是数据库中的字段名 不是属性名 默认是按升序排序--></span></strong> <map name="students" table="student_map"<strong><span style="color: #ff0000;" mce_style="color: #ff0000;"> <span style="font-size: 18px;" mce_style="font-size: 18px;">order-by="name desc"</span></span></strong>> <key column="team_id"></key> <index column="name" type="java.lang.String"></index><!-- 指定的是map中的key --> <element column="value" type="java.lang.String"></element><!-- 指定的是map中的value --> </map> </class></hibernate-mapping>建表类：CreateTable.java

package com.fgh.hibernate;import org.hibernate.cfg.Configuration;import org.hibernate.tool.hbm2ddl.SchemaExport;public class CreateTable { public static void main(String[] args) { SchemaExport export = new SchemaExport(new Configuration().configure()); export.create(true, true); }}测试类:

InsertTest.java

package com.fgh.hibernate;import java.util.Collection;import java.util.Iterator;import java.util.Map;import org.hibernate.Session;import org.hibernate.SessionFactory;import org.hibernate.Transaction;import org.hibernate.cfg.Configuration;public class InsertTest { private static SessionFactory sessionFactory; static { try { sessionFactory = new Configuration().configure() .buildSessionFactory(); } catch (Exception e) { e.printStackTrace(); } } public static void main(String[] args) { Session session = sessionFactory.openSession(); Transaction tx = null; try { // 保存操作 // Team team = new Team(); // team.setName("team1"); // // HashMap map = (HashMap) team.getStudents(); // map.put("aa", "zhangsan"); // map.put("bb", "lisi"); // map.put("ccc", "wangwu"); tx = session.beginTransaction(); // 查询操作 这里使用uniqueResult()方法返回一个唯一的对象 // 而不是返回list 方便 Team 和 name 都是指类里面的属性 Team team = (Team) session.createQuery( "from Team t where t.name = 'team1'").uniqueResult(); Map map = team.getStudents(); Collection collection = map.values(); Iterator iterator = collection.iterator(); while (iterator.hasNext()) { System.out.println(iterator.next()); } tx.commit(); } catch (Exception e) { e.printStackTrace(); if (null != tx) { tx.rollback(); } } finally { session.close(); } }}

后台打印sql：

Hibernate: select team0_.id as id0_, team0_.name as name0_ from team_map team0_ where team0_.name='team1'Hibernate: select students0_.team_id as team1_0_, students0_.value as value0_, students0_.name as name0_ from student_map students0_ where students0_.team_id=? order by students0_.name descwangwulisizhangsan