本文主要包括以下内容
- 对象的状态
- 一对多的单向关联
- 一对多的双向关联
- 多对多关联
- 一对一关联
对象状态的变化
对象的状态
临时状态
new持久化状态
get,save,update脱管状态
clear close evict
一对多单向操作，以班级表与学生表为例
Classes.java
package cn.itcast.hiberate.sh.domain;import java.io.Serializable;
import java.util.Set;public class Classes implements Serializable{private Long cid;private String cname;private String description;public Long getCid() {return cid;}public void setCid(Long cid) {this.cid = cid;}public String getCname() {return cname;}public void setCname(String cname) {this.cname = cname;}public String getDescription() {return description;}public void setDescription(String description) {this.description = description;}public Set<Student> getStudents() {return students;}public void setStudents(Set<Student> students) {this.students = students;}private Set students;
}
Student.java
package cn.itcast.hiberate.sh.domain;import java.io.Serializable;public class Student implements Serializable{private Long sid;private String sname;public Long getSid() {return sid;}public void setSid(Long sid) {this.sid = sid;}public String getSname() {return sname;}public void setSname(String sname) {this.sname = sname;}public String getDescription() {return description;}public void setDescription(String description) {this.description = description;}private String description;
}class.hbm.xml
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping><class name="cn.itcast.hiberate.sh.domain.Classes"><id name="cid" length="5" type="java.lang.Long"><generator class="increment"></generator></id><property name="cname" length="20" type="java.lang.String"></property><property name="description" length="100" type="java.lang.String"></property><!-- set元素对应类中的set集合通过set元素使classes表与student表建立关联key是通过外键的形式让两张表建立关联one-to-many是通过类的形式让两个类建立关联cascade 级联save-update1、当 保存班级的时候，对学生进行怎么样的操作如果学生对象在数据库中没有对应的值，这个时候会执行save操作如果学生对象在数据库中有对应的值，这个时候会执行update操作delete 删除班级时同时删除学生all save-update与delete都用 inverse 维护关系true 不维护关系 false 维护关系default false--><set name="students" cascade="all" inverse="false"><!-- key是用来描述外键--><key><column name="cid"></column></key><one-to-many class="cn.itcast.hiberate.sh.domain.Student"/></set></class>
</hibernate-mapping>Student.hbm.xml
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping><class name="cn.itcast.hiberate.sh.domain.Student"><id name="sid" length="5"><generator class="increment"></generator></id><property name="sname" length="20"></property><property name="description" length="100"></property></class>
</hibernate-mapping>配置文件
<?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">
<hibernate-configuration><!-- 一个session-factory只能连接一个数据库-->
<session-factory><!-- 数据库的用户名--><property name="connection.username">root</property><!-- 密码--><property name="connection.password">root</property><!-- url--><property name="connection.url">jdbc:mysql://localhost:3306/hibernate</property><!-- 作用：根据持久化类和映射文件生成表validatecreate-dropcreateupdate--><property name="hbm2ddl.auto">update</property><!-- 显示hibernate内部生成的sql语句--><property name="show_sql">true</property><mapping resource="cn/itcast/hiberate/sh/domain/Classes.hbm.xml" /><mapping resource="cn/itcast/hiberate/sh/domain/Student.hbm.xml" /></session-factory>
</hibernate-configuration>级联的概念与操作
cascade 级联save-update1、当 保存班级的时候，对学生进行怎么样的操作如果学生对象在数据库中没有对应的值，这个时候会执行save操作如果学生对象在数据库中有对应的值，这个时候会执行update操作delete 删除班级时同时删除学生all save-update与delete都用 inverse 维护关系true 不维护关系 false 维护关系default false一对多增删改查实例
package cn.itcast.hibernate.sh.test;import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;import org.hibernate.Session;
import org.hibernate.Transaction;
import org.hibernate.annotations.Type;
import org.junit.Test;import cn.itcast.hiberate.sh.domain.Classes;
import cn.itcast.hiberate.sh.domain.Student;
import cn.itcast.hibernate.sh.utils.HiberanteUtils;/*** 1、新建一个班级* 2、新建一个学生* 3、新建一个班级的时候同时新建一个学生* 4、已经存在一个班级，新建一个学生，建立学生与班级之间的关系* 5、已经存在一个学生，新建一个班级，把学生加入到该班级* 6、把一个学生从一个班级转移到另一个班级* 7、解析一个班级和一个学生之间的关系* 8、解除一个班级和一些学生之间的关系* 9、解除该班级和所有的学生之间的关系* 10、已经存在一个班级，已经存在一个学生，建立该班级与该学生之间的关系* 11、已经存在一个班级，已经存在多个学生，建立多个学生与班级之间的关系* 12、删除学生* 13、删除班级* 删除班级的时候同时删除学生* 在删除班级之前，解除班级和学生之间的关系* @author Think**/
public class OneToManySingleTest extends HiberanteUtils{@Testpublic void testSaveClasses(){Session session = sessionFactory.openSession();Transaction transaction = session.beginTransaction();Classes classes = new Classes();classes.setCname("空间信息与数字技术");classes.setDescription("pretty good");session.save(classes);transaction.commit();session.close();}@Testpublic void testSaveStudent(){Session session = sessionFactory.openSession();Transaction transaction = session.beginTransaction();Student student = new Student();student.setSname("班长");student.setDescription("老牛：很牛");session.save(student);transaction.commit();session.close();}@Testpublic void testSaveClasses_Student(){Session session = sessionFactory.openSession();Transaction transaction = session.beginTransaction();Classes classes = new Classes();classes.setCname("空间信息与数字技术2:");classes.setDescription("很牛X");Student student = new Student();student.setSname("班长");student.setDescription("老牛：很牛X");session.save(student);session.save(classes);transaction.commit();session.close();}/*** 在保存班级的时候，级联保存学生*/@Testpublic void testSaveClasses_Cascade_Student_Save(){Session session = sessionFactory.openSession();Transaction transaction = session.beginTransaction();Classes classes = new Classes();classes.setCname("空间信息与数字技术3:");classes.setDescription("很牛XX");Student student = new Student();student.setSname("班长");student.setDescription("老牛：很牛XX");Set<Student> students = new HashSet<Student>();students.add(student);//建立classes与student之间的关联classes.setStudents(students);session.save(classes);transaction.commit();session.close();}@Testpublic void testSaveClasses_Cascade_Student_Update(){Session session = sessionFactory.openSession();Transaction transaction = session.beginTransaction();Classes classes = new Classes();classes.setCname("空间信息与数字技术4:");classes.setDescription("niubility");Student student = (Student)session.get(Student.class, 2L);student.setSname("secentary");student.setDescription("it is pretty beautiful");Set<Student> students = new HashSet<Student>();students.add(student);classes.setStudents(students);session.save(classes);transaction.commit();session.close();}@Testpublic void testUpdateClasses_Cascade_Student_Save(){Session session = sessionFactory.openSession();Transaction transaction = session.beginTransaction();Classes classes = (Classes)session.get(Classes.class, 5L);Student student = new Student();student.setSname("class flower");student.setDescription("she is pretty girl");classes.getStudents().add(student);transaction.commit();session.close();}@Testpublic void testUpdateClasses_Cascade_Student_Update(){Session session = sessionFactory.openSession();Transaction transaction = session.beginTransaction();Classes classes = (Classes)session.get(Classes.class, 5L);Set<Student> students = classes.getStudents();//为cid为5的班级的所有的学生for(Student student:students){student.setDescription("under pressure");}transaction.commit();session.close();}/*** 一个错误的演示*/@Testpublic void testSaveClasses_Cascade_Student_Save_Error(){Session session = sessionFactory.openSession();Transaction transaction = session.beginTransaction();Classes classes = new Classes();classes.setCname("空间信息与数字技术5:");classes.setDescription("很牛XXXXXX");Student student = new Student();student.setSname("班长XXXXXX");student.setDescription("老牛：很牛XXXXXX");Set<Student> students = new HashSet<Student>();students.add(student);//建立classes与student之间的关联classes.setStudents(students);session.save(classes);transaction.commit();session.close();}/*** 已经存在一个班级，新建一个学生，建立学生与班级之间的关系* 通过更新班级级联保存学生 cascade* 建立班级和学生之间的关系 inverse*/@Testpublic void testSaveStudent_R_1(){Session session = sessionFactory.openSession();Transaction transaction = session.beginTransaction();Student student = new Student();student.setSname("technical");student.setDescription("good at thechnical");Classes classes = (Classes)session.get(Classes.class, 1L);classes.getStudents().add(student);transaction.commit();session.close();}/*** Hibernate: select classes0_.cid as cid0_0_, classes0_.cname as cname0_0_, classes0_.description as descript3_0_0_ from Classes classes0_ where classes0_.cid=?Hibernate: select max(sid) from StudentHibernate: select students0_.cid as cid0_1_, students0_.sid as sid1_, students0_.sid as sid1_0_, students0_.sname as sname1_0_, students0_.description as descript3_1_0_ from Student students0_ where students0_.cid=?Hibernate: insert into Student (sname, description, sid) values (?, ?, ?)更新关系的操作Hibernate: update Student set cid=? where sid=?*/@Testpublic void testSaveStudent_R_2(){Session session = sessionFactory.openSession();Transaction transaction = session.beginTransaction();Student student = new Student();student.setSname("技术班长");student.setDescription("大神");Classes classes = (Classes)session.get(Classes.class, 1L);session.save(student);classes.getStudents().add(student);transaction.commit();session.close();}/*** 已经存在一个学生，新建一个班级，把学生加入到该班级*/@Testpublic void testSaveClasses_R(){Session session = sessionFactory.openSession();Transaction transaction = session.beginTransaction();Classes classes = new Classes();classes.setCname("空间信息与数字技术6");classes.setDescription("必看，杀手锏");Student student = (Student)session.get(Student.class, 2L);Set<Student> students = new HashSet<Student>();students.add(student);classes.setStudents(students);session.save(classes);transaction.commit();session.close();}/*** 把一个学生从一个班级转移到另一个班级* Hibernate: select classes0_.cid as cid0_0_, classes0_.cname as cname0_0_, classes0_.description as descript3_0_0_ from Classes classes0_ where classes0_.cid=?Hibernate: select classes0_.cid as cid0_0_, classes0_.cname as cname0_0_, classes0_.description as descript3_0_0_ from Classes classes0_ where classes0_.cid=?Hibernate: select student0_.sid as sid1_0_, student0_.sname as sname1_0_, student0_.description as descript3_1_0_ from Student student0_ where student0_.sid=?Hibernate: select students0_.cid as cid0_1_, students0_.sid as sid1_, students0_.sid as sid1_0_, students0_.sname as sname1_0_, students0_.description as descript3_1_0_ from Student students0_ where students0_.cid=?Hibernate: select students0_.cid as cid0_1_, students0_.sid as sid1_, students0_.sid as sid1_0_, students0_.sname as sname1_0_, students0_.description as descript3_1_0_ from Student students0_ where students0_.cid=?Hibernate: update Student set cid=null where cid=? and sid=?Hibernate: update Student set cid=? where sid=?*/@Testpublic void testTransformClass(){Session session = sessionFactory.openSession();Transaction transaction = session.beginTransaction();//Classes classes5 = (Classes)session.get(Classes.class, 5L);Classes classes6 = (Classes)session.get(Classes.class, 6L);Student student = (Student)session.get(Student.class, 1L);//classes5.getStudents().remove(student);classes6.getStudents().add(student);transaction.commit();session.close();}/*** 解除一个班级和一些学生之间的关系*/@Testpublic void testR_Some(){Session session = sessionFactory.openSession();Transaction transaction = session.beginTransaction();Classes classes = (Classes)session.get(Classes.class, 1L);Set<Student> students = classes.getStudents();
// for(Student student:students){
// if(student.getSid().longValue()==6||student.getSid().longValue()==7){
// students.remove(student);
// }
// }//set-->list(set转化成list)List<Student> sList = new ArrayList<Student>(students);for(int i=0;i<sList.size();i++){if(sList.get(i).getSid().longValue()==6||sList.get(i).getSid().longValue()==7){sList.remove(sList.get(i));i--;}}//list转化成setstudents = new HashSet<Student>(sList);classes.setStudents(students);/*** 增强for循环只能修改一次* 1、用普通的for循环* 2、新建一个set集合，把原来的set集合要保留的数据存放到新的set集合中*/transaction.commit();session.close();}/** 解除班级与所有学生* classes.setStudents(null);直接把班级针对student的集合设置为null*/@Testpublic void testRealseAll(){Session session = sessionFactory.openSession();Transaction transaction = session.beginTransaction();Classes classes = (Classes)session.get(Classes.class, 1L);
// Set<Student> students = classes.getStudents();
// students.clear();classes.setStudents(null);transaction.commit();session.close();}/*** 已经存在一个班级，已经存在一个学生，建立该班级与该学生之间的关系* 11、已经存在一个班级，已经存在多个学生，建立多个学生与班级之间的关系*///删除一个学生@Testpublic void testDeleteStudent(){Session session = sessionFactory.openSession();Transaction transaction = session.beginTransaction();Student student = (Student)session.get(Student.class, 8L);session.delete(student);transaction.commit();session.close();}//删除班级@Testpublic void testDeleteClasses(){Session session = sessionFactory.openSession();Transaction transaction = session.beginTransaction();Classes classes = (Classes)session.get(Classes.class, 5L);//classes.setStudents(null);session.delete(classes);transaction.commit();session.close();}@Testpublic void testDeleteClasses_Cascade(){Session session = sessionFactory.openSession();Transaction transaction = session.beginTransaction();Classes classes = (Classes)session.get(Classes.class, 5L);session.delete(classes);transaction.commit();session.close();}}一对多的双向关联
双向关联时Student.java和Student.hbm.xml文件都需要修改
package cn.itcast.hiberate.sh.domain;import java.io.Serializable;public class Student implements Serializable{private Long sid;private String sname;private Classes classes;public Classes getClasses() {return classes;}public void setClasses(Classes classes) {this.classes = classes;}public Long getSid() {return sid;}public void setSid(Long sid) {this.sid = sid;}public String getSname() {return sname;}public void setSname(String sname) {this.sname = sname;}public String getDescription() {return description;}public void setDescription(String description) {this.description = description;}private String description;
}Student.hbm.xml
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping><class name="cn.itcast.hiberate.sh.domain.Student"><id name="sid" length="5"><generator class="increment"></generator></id><property name="sname" length="20"></property><property name="description" length="100"></property><!-- 多对一column 外键--><many-to-one name="classes" class="cn.itcast.hiberate.sh.domain.Classes" column="cid" cascade="save-update" unique="true"></many-to-one></class>
</hibernate-mapping>一对多双向操作的实例
package cn.itcast.hibernate.sh.test;import java.util.HashSet;
import java.util.Set;import org.hibernate.Session;
import org.hibernate.Transaction;
import org.junit.Test;import cn.itcast.hiberate.sh.domain.Classes;
import cn.itcast.hiberate.sh.domain.Student;
import cn.itcast.hibernate.sh.utils.HiberanteUtils;/*** 3、新建一个班级的时候同时新建一个学生* 4、已经存在一个班级，新建一个学生，建立学生与班级之间的关系* 5、已经存在一个学生，新建一个班级，把学生加入到该班级* 6、把一个学生从一个班级转移到另一个班级* 7、解析一个班级和一个学生之间的关系* 8、解除一个班级和一些学生之间的关系* 9、解除该班级和所有的学生之间的关系* 10、已经存在一个班级，已经存在一个学生，建立该班级与该学生之间的关系* 11、已经存在一个班级，已经存在多个学生，建立多个学生与班级之间的关系* 12、删除学生* 13、删除班级* 删除班级的时候同时删除学生* 在删除班级之前，解除班级和学生之间的关系* @author Think**/
public class OneToManyTest extends HiberanteUtils{static{//url = "hibernate.cfg.xml";}@Testpublic void testSaveStudent_Cascade_Classes_Save(){Session session = sessionFactory.openSession();Transaction transaction = session.beginTransaction();Student student = new Student();student.setSname("class scentary");student.setDescription("a mysterous job");Classes classes = new Classes();classes.setCname("class1");classes.setDescription("interesting");student.setClasses(classes);
// Set<Student> students = new HashSet<Student>();
// students.add(student);
//
// classes.setStudents(students);session.save(student);transaction.commit();session.close();}/*** 一对多，从多的一端维护关系效率比较高*/@Testpublic void testSaveStudent_R(){Session session = sessionFactory.openSession();Transaction transaction = session.beginTransaction();Student student = new Student();student.setSname("zj");student.setDescription("pretty good");Classes classes = (Classes)session.get(Classes.class, 2L);student.setClasses(classes);/*Set<Student> students = new HashSet<Student>();students.add(student);classes.getStudents().add(student);//在hibernate内部查看的是classes.hbm.xml*/session.save(student);//在hibernate内部查看的是Student.hbm.xmltransaction.commit();session.close();}@Testpublic void testRelese_R(){Session session = sessionFactory.openSession();Transaction transaction = session.beginTransaction();Classes classes = (Classes)session.get(Classes.class, 2L);Student student7 = (Student)session.get(Student.class, 7L);Student student8 = (Student)session.get(Student.class, 8L);student7.setClasses(null);student8.setClasses(null);transaction.commit();session.close();}//在删除前必须解除关系，从classes得到，必须从classes删除，或者将cascade="all"@Testpublic void testDeleteS(){Session session = sessionFactory.openSession();Transaction transaction = session.beginTransaction();Classes classes = (Classes)session.get(Classes.class, 1L); Set<Student> students = classes.getStudents();//classes.setStudents(null);//解除关系for(Student student:students){session.delete(student);}transaction.commit();session.close();}
}注意
在删除时要注意解除关系
1、根据映射文件可以得出classes与student有关联
2、在客户端，students是由classes产生的，代表了关联关系
3、所以在删除student的时候，必须通过classes解除关系
4、解除关系以后才能进行删除
一对多的总结
1、如果让一的一方维护关系，取决于的因素有
1、在一的一方的映射文件中，set元素的inverse属性为default/false
2、在客户端的代码中，通过一的一方建立关系
3、session.save/update方法是用来操作表的，和操作关系没有关系
2、怎么样采用级联的方法通过保存一个对象从而保存关联对象
1、如果session.save操作的对象是A，这个时候应该看A.hbm.xml,看set元素中cascade是否设置有级联保存
2、在客户端通过A建立关联
3、在客户端执行session.save(A)
3、一对多的情况，多的一方维护关系效率比较高
1、在多的一方many-to-one中没有inverse属性
2、在客户端通过多的一方建立关联
多对多关联
由于配置文件位置可能改变，HiberanteUtils文件修改如下
package cn.itcast.hibernate.sh.utils;import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.junit.Before;public class HiberanteUtils {public static SessionFactory sessionFactory;public static String url;//子类与父类同时有static,先执行父类的static语句块，所以这种方法不行
// static{
// /**
// * 创建configuration对象
// */
// Configuration configuration = new Configuration();
// configuration.configure(url);
// /**
// * 加载hibernate的配置文件
// */
// //configuration.configure("");
// sessionFactory = configuration.buildSessionFactory();
// }//注意：在test方法执行之前执行before,JUnit的特性方法@Beforepublic void init(){Configuration configuration = new Configuration();configuration.configure(url);/*** 加载hibernate的配置文件*///configuration.configure("");sessionFactory = configuration.buildSessionFactory();}
}多对多用一个Course类和Student类做示例
Student.java
package cn.itcast.hiberate.sh.domain.manytomany;import java.io.Serializable;
import java.util.Set;public class Student implements Serializable{private Long sid;private String sname;private String description;public Long getSid() {return sid;}public void setSid(Long sid) {this.sid = sid;}public String getSname() {return sname;}public void setSname(String sname) {this.sname = sname;}public String getDescription() {return description;}public void setDescription(String description) {this.description = description;}public Set<Course> getCourses() {return courses;}public void setCourses(Set<Course> courses) {this.courses = courses;}private Set<Course> courses;
}Student.hbm.xml
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping><class name="cn.itcast.hiberate.sh.domain.manytomany.Student"><id name="sid" type="java.lang.Long" length="5"><generator class="increment"></generator></id><property name="sname" type="java.lang.String" length="20"></property><property name="description" length="100"></property><!-- table就是用来描述第三张表,多对多时才会出现这个属性--><set name="courses" table="student_course" cascade="all"><key><column name="sid"></column></key><many-to-many class="cn.itcast.hiberate.sh.domain.manytomany.Course" column="cid"></many-to-many></set></class>
</hibernate-mapping>Course.java
package cn.itcast.hiberate.sh.domain.manytomany;import java.io.Serializable;
import java.util.Set;public class Course implements Serializable{private Long cid;private String cname;public Long getCid() {return cid;}public void setCid(Long cid) {this.cid = cid;}public String getCname() {return cname;}public void setCname(String cname) {this.cname = cname;}public String getDescription() {return description;}public void setDescription(String description) {this.description = description;}public Set<Student> getStudents() {return students;}public void setStudents(Set<Student> students) {this.students = students;}private String description;private Set<Student> students;
}Course.hbm.xml
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping><class name="cn.itcast.hiberate.sh.domain.manytomany.Course"><id name="cid" length="5"><generator class="increment"></generator></id><property name="cname" length="20"></property><property name="description" length="100"></property><set name="students" table="student_course" cascade="all"><key><column name="cid"></column></key><many-to-many class="cn.itcast.hiberate.sh.domain.manytomany.Student" column="sid"></many-to-many></set></class>
</hibernate-mapping>第三张表的名字是student_course，两个映射文件中定义时必须一致
多对多实例操作
package cn.itcast.hibernate.sh.test;import java.util.HashSet;
import java.util.List;
import java.util.Set;import org.hibernate.Session;
import org.hibernate.Transaction;
import org.junit.Test;import cn.itcast.hiberate.sh.domain.manytomany.Course;
import cn.itcast.hiberate.sh.domain.manytomany.Student;
import cn.itcast.hibernate.sh.utils.HiberanteUtils;/*** 1、新建一个课程* 2、新建一个学生* 3、新建课程的同时新建学生 级联* 4、已经存在一个课程，新建一个学生，建立课程和学生之间的关系* 5、已经存在一个学生，新建一个课程，建立课程和学生之间的关系* 6、已经存在一个课程，已经存在一个学生，建立关联* 7、把已经存在的一些学生加入到已经存在的一个课程中* 8、把一个学生加入到一些课程中* 9、把多个学生加入到多个课程中* 10、把一个已经存在的学生从一个已经的课程中移除* 11、把一些学生从一个已经存在的课程中移除* 12、把一个学生从一个课程转向到另外一个课程* 13、删除课程* 14、删除学生* @author Think**/
public class ManyToManyTest extends HiberanteUtils{static{url = "cn/itcast/hiberate/sh/domain/manytomany/hibernate.cfg.xml";}@Testpublic void testCreateTable(){}@Testpublic void testSaveStudent_Cascade_Course_Save(){Session session = sessionFactory.openSession();Transaction transaction = session.beginTransaction();Student student = new Student();student.setSname("monitor3");student.setDescription("nubility");Course course = new Course();course.setCname("science");course.setDescription("pretty good");Set<Course> courses = new HashSet<Course>();courses.add(course);student.setCourses(courses);session.save(student);transaction.commit();session.close();}/*** 已经存在一个课程，新建一个学生，建立课程和学生之间的关系* 从课程角度出发*/@Testpublic void testUpdateCourse_Cascade_Student_Save_R(){Session session = sessionFactory.openSession();Transaction transaction = session.beginTransaction();Course course = (Course)session.get(Course.class, 1L);Student student = new Student();student.setSname("class fans");student.setDescription("fansof student");course.getStudents().add(student);//session.save(student);transaction.commit();session.close();}/*** 已经存在一个课程，新建一个学生，建立课程和学生之间的关系* 从学生角度出发*/@Testpublic void testSaveStudent_R(){Session session = sessionFactory.openSession();Transaction transaction = session.beginTransaction();Course course = (Course)session.get(Course.class, 1L);Student student = new Student();student.setSname("zj");student.setDescription("never");Set<Course> courses = new HashSet<Course>();courses.add(course);student.setCourses(courses);session.save(student);transaction.commit();session.close();}/*** 已经存在一个课程，已经存在一个学生，建立关联*/@Testpublic void testR(){Session session = sessionFactory.openSession();Transaction transaction = session.beginTransaction();Course course = (Course)session.get(Course.class, 1L);Student student = (Student)session.get(Student.class, 2L);student.getCourses().add(course);transaction.commit();session.close();}/*** 把学生3,4加入到课程1中*/@Testpublic void testR_Some(){Session session = sessionFactory.openSession();Transaction transaction = session.beginTransaction();Course course = (Course)session.get(Course.class, 1L);Student student = (Student)session.get(Student.class, 3L);Student student2 = (Student)session.get(Student.class, 4L);
// student.getCourses().add(course);
// student2.getCourses().add(course);course.getStudents().add(student2);course.getStudents().add(student);transaction.commit();session.close();}/*** 把一个学生加入到一些课程中*/@Testpublic void testR_Some_2(){Session session = sessionFactory.openSession();Transaction transaction = session.beginTransaction();Student student = (Student)session.get(Student.class, 3L);List<Course> courseList = session.createQuery("from Course where cid in(1,2,3)").list();student.getCourses().addAll(courseList);transaction.commit();session.close();}/*** 把学生从一个课程转移到另外一个课程*/@Testpublic void testTransform(){Session session = sessionFactory.openSession();Transaction transaction = session.beginTransaction();Student student = (Student) session.get(Student.class, 3L);Course course1 = (Course)session.get(Course.class, 1L);Course course3 = (Course)session.get(Course.class, 3L);student.getCourses().remove(course1);student.getCourses().add(course3);transaction.commit();session.close();}
}一对一关联,以person表与adress表为例
person.java
package cn.itcast.hiberate.sh.domain.onetoone;import java.io.Serializable;
import java.util.Set;public class Person implements Serializable{private Long cid;private String cname;private String description;public Long getCid() {return cid;}public void setCid(Long cid) {this.cid = cid;}public String getCname() {return cname;}public void setCname(String cname) {this.cname = cname;}public String getDescription() {return description;}public void setDescription(String description) {this.description = description;}public Address getAddress() {return address;}public void setAddress(Address address) {this.address = address;}private Address address;
}Person.hbm.xml
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping><class name="cn.itcast.hiberate.sh.domain.onetoone.Person"><id name="cid" length="5" type="java.lang.Long"><generator class="foreign"><param name="property">address</param></generator></id><property name="cname" length="20" type="java.lang.String"></property><property name="description" length="100" type="java.lang.String"></property><one-to-one name="address" class="cn.itcast.hiberate.sh.domain.onetoone.Address" constrained="true"></one-to-one></class>
</hibernate-mapping>注意constrained=”true”
adress.java与adress.hbm.xml
package cn.itcast.hiberate.sh.domain.onetoone;import java.io.Serializable;public class Address implements Serializable{private Long sid;private String sname;private Person person;public Person getPerson() {return person;}public void setPerson(Person person) {this.person = person;}public Long getSid() {return sid;}public void setSid(Long sid) {this.sid = sid;}public String getSname() {return sname;}public void setSname(String sname) {this.sname = sname;}public String getDescription() {return description;}public void setDescription(String description) {this.description = description;}private String description;
}一般one-to-one只单向关联
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping><class name="cn.itcast.hiberate.sh.domain.onetoone.Address"><id name="sid" length="5"><generator class="increment"></generator></id><property name="sname" length="20"></property><property name="description" length="100"></property></class>
</hibernate-mapping>
