hibernate 2 ?多对多映射

 1 package cn.gs.wwg.entity; 2 ?3 import java.util.Set; 4 ?5 public class Classes { 6 ????private int cid; 7 ????private String cname; 8 ????private String cdescription; 9 ????private Set<Student> students;10 ????public int getCid() {11 ????????return cid;12 ????}13 ????public void setCid(int cid) {14 ????????this.cid = cid;15 ????}16 ????public String getCname() {17 ????????return cname;18 ????}19 ????public void setCname(String cname) {20 ????????this.cname = cname;21 ????}22 ????public String getCdescription() {23 ????????return cdescription;24 ????}25 ????public void setCdescription(String cdescription) {26 ????????this.cdescription = cdescription;27 ????}28 ????public Set<Student> getStudents() {29 ????????return students;30 ????}31 ????public void setStudents(Set<Student> students) {32 ????????this.students = students;33 ????}34 ????35 }

 1 package cn.gs.wwg.entity; 2 ?3 import java.io.Serializable; 4 import java.util.Set; 5 ?6 public class Student implements Serializable{ 7 ????private int sid; 8 ????private String sname; 9 ????private String sdescription;10 ????private Set<Classes> classes;11 ????12 13 ????public Set<Classes> getClasses() {14 ????????return classes;15 ????}16 ????public void setClasses(Set<Classes> classes) {17 ????????this.classes = classes;18 ????}19 ????public int getSid() {20 ????????return sid;21 ????}22 ????public void setSid(int sid) {23 ????????this.sid = sid;24 ????}25 ????public String getSname() {26 ????????return sname;27 ????}28 ????public void setSname(String sname) {29 ????????this.sname = sname;30 ????}31 ????public String getSdescription() {32 ????????return sdescription;33 ????}34 ????public void setSdescription(String sdescription) {35 ????????this.sdescription = sdescription;36 ????}37 ????38 }

 1 <?xml version="1.0" encoding="UTF-8"?> 2 <!DOCTYPE hibernate-mapping PUBLIC ?3 ????"-//Hibernate/Hibernate Mapping DTD 3.0//EN" 4 ????"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> 5 <hibernate-mapping> 6 ????<!-- ?7 ????????class 用来描述一个持久化类 8 ????????name:持久化类全名 9 ????????table: 表名 可以不写 默认和实体类名一致10 ?????-->11 ????<class name="cn.gs.wwg.entity.Classes" >12 ????????<!-- 13 ????????????标示属性 和数据库中主键对应14 ?????????-->15 ????????<id name="cid" column="cid" type="java.lang.Integer">16 ????????????<!-- 主键产生器 -->17 ????????????<generator class="assigned">18 19 ????????????</generator>20 ????????</id>21 ????????<property name="cname" column="cname" type="java.lang.String"></property>22 ????????<property name="cdescription" column="cdescription" type="java.lang.String"></property>23 ????????<!-- 24 ????????????cascade="save-update"25 ????????????当保存班级的时候对学生进行什么样的操作26 ?????????-->27 ????????<set name="students" table="student_classes" cascade="all">28 ????????????<!-- key用来描述外键29 ????????????????set元素对应了classes类中的集合30 ????????????????通过key是通过外键的形式将两张表建立联系31 ????????????????通过one-to-many让两个类建立关联32 ?????????????-->33 ????????????<key>34 ????????????????<column name="cid"></column>35 ????????????</key>36 ????????????<many-to-many class="cn.gs.wwg.entity.Student" column="sid"></many-to-many>37 ????????</set>38 ????</class>39 </hibernate-mapping>

 1 <?xml version="1.0" encoding="UTF-8"?> 2 <!DOCTYPE hibernate-mapping PUBLIC ?3 ????"-//Hibernate/Hibernate Mapping DTD 3.0//EN" 4 ????"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> 5 <hibernate-mapping> 6 ????<!-- ?7 ????????class 用来描述一个持久化类 8 ????????name:持久化类全名 9 ????????table: 表名 可以不写 默认和实体类名一致10 ?????-->11 ????<class name="cn.gs.wwg.entity.Student" >12 ????????<!-- 13 ????????????标示属性 和数据库中主键对应14 ?????????-->15 ????????<id name="sid" column="sid" type="java.lang.Integer">16 ????????????<!-- 主键产生器 -->17 ????????????<generator class="assigned">18 19 ????????????</generator>20 ????????</id>21 ????????<property name="sname" column="sname" type="java.lang.String"></property>22 ????????<property name="sdescription" column="sdescription" type="java.lang.String"></property>23 ???????????<!-- 24 ???????????????多对一 column 描述外键25 ????????????-->26 ???????????<set name="classes" table="student_classes" cascade="all">27 ????????????<!-- key用来描述外键28 ????????????????set元素对应了classes类中的集合29 ????????????????通过key是通过外键的形式将两张表建立联系30 ????????????????通过one-to-many让两个类建立关联31 ?????????????-->32 ????????????<key>33 ????????????????<column name="sid"></column>34 ????????????</key>35 ????????????<many-to-many class="cn.gs.wwg.entity.Classes" column="cid"></many-to-many>36 ????????</set>37 ????</class>38 </hibernate-mapping>

 1 <?xml version="1.0" encoding="UTF-8"?> 2 <!DOCTYPE hibernate-configuration PUBLIC 3 ????"-//Hibernate/Hibernate Configuration DTD 3.0//EN" 4 ????"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"> 5 ?????6 <hibernate-configuration> 7 ????<!-- 一个session-factory只能链接一个数据库 ?--> 8 ????<session-factory> 9 ????????<!-- 10 ????????进行数据库连接11 ????????????driver:驱动12 ????????????url:地址13 ????????????username:数据库连接用户名14 ????????????password:数据库连接密码15 ????????????数据库方言16 ??????????????????不同的数据库中,sql语法略有区别. 指定方言可以让hibernate框架在生成sql语句时.针对数据库的方言生成.17 ??????????????sql99标准: DDL 定义语言 ?库表的增删改查18 ??????????????????????DCL 控制语言 ?事务 权限19 ??????????????????????DML 操纵语言 ?增删改查20 ?????????????注意: MYSQL在选择方言时,请选择最短的方言. ???????????21 ?????????-->22 ?????????<property name="dialect">org.hibernate.dialect.Oracle10gDialect</property>23 ?????????<property name="connection.driver_class">oracle.jdbc.driver.OracleDriver</property>24 ?????????<property name="connection.url">jdbc:oracle:thin:@localhost:1521:orcl</property>25 ?????????<property name="connection.username">liuyang</property>26 ?????????<property name="connection.password">orcl</property>27 ?????????<!-- 28 ?????????????自动建表 ?29 ???????????????auto schema export ?自动导出表结构. 自动建表30 ???????????????hibernate.hbm2ddl.auto create ?????自动建表.每次框架运行都会创建新的表.以前表将会被覆盖,表数据会丢失.(开发环境中测试使用)31 ???????????????hibernate.hbm2ddl.auto create-drop 自动建表.每次框架运行结束都会将所有表删除.(开发环境中测试使用)32 ???????????????hibernate.hbm2ddl.auto update(推荐使用) 自动生成表.如果已经存在不会再生成.如果表有变动.自动更新表(不会删除任何数据).33 ???????????????hibernate.hbm2ddl.auto validate ???校验.不自动生成表.每次启动会校验数据库中表是否正确.校验失败.34 ?????????-->35 <!-- ?????????<property name="hbm2ddl.auto">update</property> -->36 ?????????<property name="hbm2ddl.auto">update</property>37 ?????????38 ?????????<!-- 将hibernate生成的sql语句打印到控制台 -->39 ?????????<property name="show_sql">true</property> ???40 ?????????<!-- 添加映射文件 --> ???????41 <!-- ?????????<mapping resource="cn/gs/ly/entity/Person.hbm.xml"></mapping> ?????-->42 <!-- ?????????<mapping resource="cn/gs/ly/school/entity/Student.hbm.xml"></mapping> ?????????-->43 <!-- ?????????<mapping resource="cn/gs/ly/school/entity/Classes.hbm.xml"></mapping> ????-->44 ?????????<mapping resource="cn/gs/wwg/entity/Classes.hbm.xml"></mapping> ???45 ?????????<mapping resource="cn/gs/wwg/entity/Student.hbm.xml"></mapping> 46 ????</session-factory>47 </hibernate-configuration>

 ?1 package cn.gs.wwg.entity.test; ?2 ??3 import java.util.HashSet; ?4 import java.util.List; ?5 import java.util.Set; ?6 ??7 import org.hibernate.Session; ?8 import org.hibernate.SessionFactory; ?9 import org.hibernate.Transaction; 10 import org.hibernate.cfg.Configuration; 11 import org.junit.After; 12 import org.junit.Before; 13 import org.junit.Test; 14 ?15 import cn.gs.wwg.entity.Classes; 16 import cn.gs.wwg.entity.Student; 17 ?18 public class ManyToManyTest { 19 ?????20 ????SessionFactory factory =null; 21 ????Session se = null; 22 ????Transaction tr = null; 23 ?????24 ????@Before 25 ????public void beforeStart(){ 26 ????????Configuration con = new Configuration(); 27 ????????con.configure(); 28 ????????factory = con.buildSessionFactory(); 29 ????????se = factory.openSession(); 30 ????????tr = se.beginTransaction(); 31 ????} 32 ????@After 33 ????public void afterClose(){ 34 ????????tr.commit(); 35 ????????se.close(); 36 ????} 37 ?????38 ????//3.新建一个班级的同时新建一个学生 39 ????@Test 40 ????public void testSaveStudent_Cascade_classes_Save(){ 41 ?????????42 ????????Student student = new Student(); 43 ????????student.setSid(1); 44 ????????student.setSname("小明"); 45 ????????student.setSdescription("调皮捣蛋"); 46 ?????????47 ????????Classes classes = new Classes(); 48 ????????classes.setCid(1); 49 ????????classes.setCname("gs01"); 50 ????????classes.setCdescription("有上升空间"); 51 ?????????52 // ???????Set<Classes> cla = new HashSet<Classes>(); 53 // ???????cla.add(classes); 54 // ???????student.setClasses(cla); 55 ????????Set<Student> stu = new HashSet<Student>();//实例化一个Set集合存放学生 56 ????????stu.add(student); //把学生添加到集合中 57 ????????classes.setStudents(stu); 58 ????????se.save(classes); 59 ?60 ????} 61 ?????62 ????// 4.已经存在一个班级，新建一个学生 建立联系 ?inverse (班级) 63 ????@Test 64 ????public void testUpdateclasses_Cascade_Student_Save_R(){ 65 ????????Classes classes = (Classes)se.get(Classes.class, 1); 66 ????????Student student = new Student(); 67 ????????student.setSid(2); 68 ????????student.setSname("萌萌"); 69 ????????student.setSdescription("萌男人"); ????????70 ????????classes.getStudents().add(student); 71 ????????//se.save(student); ?72 ?73 ????} 74 ?????75 ????// 4.已经存在一个班级，新建一个学生 建立联系 ?inverse (学生) 76 ????@Test 77 ????public void testSaveStudent_R(){ 78 ????????Classes classes = (Classes)se.get(Classes.class, 1); 79 ????????Student student = new Student(); 80 ????????student.setSid(3); 81 ????????student.setSname("神秘人"); 82 ????????student.setSdescription("未知"); 83 ????????Set<Classes> cla = new HashSet<Classes>(); 84 ????????cla.add(classes); 85 ????????student.setClasses(cla); 86 ????????se.save(student); 87 ?88 ????} 89 ?????90 ????//5.已经存在一个学生，新建一个班级 ?91 ????@Test 92 ????public void testSaveStudent_CreateClass(){ 93 ????????Student student = (Student)se.get(Student.class, 4); 94 ????????Classes classes = new Classes(); 95 ????????classes.setCid(2); 96 ????????classes.setCname("gs02"); 97 ????????classes.setCdescription("一群学霸"); 98 ????????student.getClasses().add(classes); 99 ????}100 ????101 ????//6.把一个学生从一个班级转到另一个班级。102 ????@Test103 ????public void testTransform(){ ???????104 ????????Student student = (Student) se.get(Student.class, 1);//学生1从1班转到2班105 ????????Classes classes1 = (Classes)se.get(Classes.class, 1);106 ????????Classes classes2 = (Classes)se.get(Classes.class, 2);107 ????????student.getClasses().remove(classes1);108 ????????student.getClasses().add(classes2);109 ????}110 ????111 ????//8.解除一个班级和一些学生的关系112 ????@Test113 ????public void test_Some(){114 ????????Student student = (Student)se.get(Student.class, 1);115 ????????Student student2 = (Student)se.get(Student.class, 2);116 ????????student.setClasses(null);117 ????????student2.setClasses(null);118 ????}119 ????120 ????//11.已经存在了一个班级，也存在许多学生 建立班级与学生的关系。方法一121 ????@Test122 ????public void testR_Some(){123 ????????Classes classes = (Classes)se.get(Classes.class,1);124 ????????Student student = (Student)se.get(Student.class, 1);125 ????????Student student2 = (Student)se.get(Student.class, 2);126 ????????student.getClasses().add(classes);127 ????????student2.getClasses().add(classes);128 // ???????classes.getStudents().add(student2);Ч???129 // ???????classes.getStudents().add(student);130 ????}131 ????132 ????//11.已经存在了一个班级，也存在许多学生 建立班级与学生的关系。方法二133 ????@Test134 ????public void testR_Some_2(){135 ????????Classes classes = (Classes)se.get(Classes.class,1);136 ????????List<Student> studentList = se.createQuery("from Student where sid in(1,2)").list();137 ????????classes.getStudents().addAll(studentList);138 ????}139 ????140 ????//12.已经存在了一些班级，也存在许多学生 建立班级与学生的关系。（每名学生都有多个班级）141 ????@Test142 ????public void testR_Some_3(){143 ????????List<Student> studentList = se.createQuery("from Student where sid in(3,4)").list();144 ????????List<Classes> classesList = se.createQuery("from Classes where cid in(1,2)").list();145 ????????for(Student s:studentList){146 ????????????s.getClasses().addAll(classesList); //学生3、4都关联两个班级1、2147 ????????} ???????148 ????}149 ????150 ????//13.删除班级151 ????@Test152 ????public void testR_Some_5(){153 ????????Classes classes = (Classes)se.get(Classes.class, 2);154 ????????//classes.setStudents(null); ?//解除关系 ??inverse="true"时需此操作155 ????????se.delete(classes); ???156 ????}157 }