hibernate OneToMany (Annotation)

 //Students類 外鍵是classId引用ClassName中的ClassId

package com.hibernate_oneTomany;

import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;

@Entity
@Table(name="t_stu")
public class Students {
 
 private String id;
 
 private String name;
 
 private ClassName clazz;
 
 @Id
 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;
 }

 @ManyToOne
 @JoinColumn(name="classId")
 public ClassName getClazz() {
  return clazz;
 }

 public void setClazz(ClassName clazz) {
  this.clazz = clazz;
 }
 
}

//ClassName是班級類，主鍵是classId且爲Students中classId的外鍵

package com.hibernate_oneTomany;

import java.util.HashSet;
import java.util.Set;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.Table;

@Entity
@Table(name="t_class")
public class ClassName {

 private String classId;
 
 private String className;
 
 private Set<Students> sets = new HashSet<Students>();

 @Id
 @Column(name="classId")
 public String getClassId() {
  return classId;
 }

 public void setClassId(String classId) {
  this.classId = classId;
 }

 public String getClassName() {
  return className;
 }

 public void setClassName(String className) {
  this.className = className;
 }
 
 @OneToMany(mappedBy="clazz")
 public Set<Students> getSets() {
  return sets;
 }

 public void setSets(Set<Students> sets) {
  this.sets = sets;
 }
}

//測試類

package com.hibernate_oneTomany;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;

public class Test {

 public static void main(String[] args) {
  
  AnnotationConfiguration af = new AnnotationConfiguration();
  SessionFactory sf = af.configure().buildSessionFactory();
  Session session = sf.openSession();
  session.beginTransaction();
  Students stu = new Students();
  ClassName cls = new ClassName();
  cls.setClassId("2");
  cls.setClassName("bb");
  stu.setId("aaa");
  stu.setName("wangwu");
  stu.setClazz(cls);
  
  session.save(cls);
  session.save(stu);
  
  session.beginTransaction().commit();
 }

}

 

//hibernate.cfg.xml中的配置

<!DOCTYPE hibernate-configuration PUBLIC
 "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
 "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>
 <session-factory>
  <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
  <property name="connection.url">jdbc:mysql://localhost:3306/test?useUnicode=true&amp;characterEncoding=utf8</property>
  <property name="connection.username">root</property>
  <property name="connection.password">123</property>
  <property name="show_sql">true</property>
  <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
  <!-- <mapping resource="com/hibernate/po/User.hbm.xml"/> 
  <mapping class="com.hibernate_onetoonepk.Students"></mapping>
  <mapping class="com.hibernate_onetoonepk.StuID"></mapping> -->
  <mapping class="com.hibernate_oneTomany.Students"></mapping>
  <mapping class="com.hibernate_oneTomany.ClassName"></mapping>
 </session-factory>
</hibernate-configuration>