hibernate3 一对多多对一单向关联级联增删改查

hibernate中如何对一对多，多对一的单向关联进行级联的crud操作呢，主要使用cascade与fetch
例子如下：
首先是@OneToMany跟@ManyToOne中cascade属性的设置，查看hibernate annotation
文档可以看到cascade属性有几个取值，我们使用ALL来操作，cascade={CascadeType.ALL}
表示对级联的对象进行cud操作时候都进行级联操作(PS:进行读取操作的时候不级联)，
进行读取操作的时候要设置fetch的属性,fetch=FetchType.EAGER,onetomany这方默认是LAZY，
manytoone这方默认是EAGER。
－－－－－－－－－－Group类如下：
import java.util.HashSet;
import java.util.Set;

import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToMany;
import javax.persistence.Table;

@Entity
@Table(name="t_group")
public class Group {
 private int id;
 private String name;
 private Set<User> users = new HashSet<User>();
 @Id
 @GeneratedValue
 public int getId() {
  return id;
 }
 public void setId(int id) {
  this.id = id;
 }
 public String getName() {
  return name;
 }
 public void setName(String name) {
  this.name = name;
 }
 @OneToMany(mappedBy="group",
  cascade={CascadeType.ALL}
     //fetch=FetchType.EAGER
  )
 
 public Set<User> getUsers() {
  return users;
 }
 public void setUsers(Set<User> users) {
  this.users = users;
 }
}
－－－－－－－－－－－－－－－User类如下：
import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.ManyToOne;
import javax.persistence.Table;

@Entity
@Table(name="t_user")
public class User {
 private int id;
 private String name;
 private Group group;
 @ManyToOne(cascade={CascadeType.ALL})
 public Group getGroup() {
  return group;
 }
 public void setGroup(Group group) {
  this.group = group;
 }
 @Id
 @GeneratedValue
 public int getId() {
  return id;
 }
 public void setId(int id) {
  this.id = id;
 }
 public String getName() {
  return name;
 }
 public void setName(String name) {
  this.name = name;
 }
}
－－－－－－－－－－－－－－hibernate.cfg.xml配置文件如下：
<?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>

    <session-factory>

        
        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="connection.url">jdbc:mysql://localhost/hibernate</property>
        <property name="connection.username">root</property>
        <property name="connection.password">heavenlin1</property>
        <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
       <!--
        <property name="connection.driver_class">oracle.jdbc.driver.OracleDriver</property>
        <property name="connection.url">jdbc:oracle:thin:@localhost:1521:SXT</property>
        <property name="connection.username">scott</property>
        <property name="connection.password">tiger</property>
       <property name="dialect">org.hibernate.dialect.OracleDialect</property>
       -->

        <!-- JDBC connection pool (use the built-in) -->
        <property name="connection.pool_size">1</property>

 

        <!-- Enable Hibernate's automatic session context management -->
        <property name="current_session_context_class">thread</property>

        <!-- Disable the second-level cache  -->
        <property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>

        <!-- Echo all executed SQL to stdout -->
        <property name="show_sql">true</property>
        <property name="format_sql">true</property>

        <!-- Drop and re-create the database schema on startup
        <property name="hbm2ddl.auto">update</property>
   -->
  <mapping class="com.bjsxt.hibernate.Group"/>
  <mapping class="com.bjsxt.hibernate.User"/>
  
    </session-factory>

</hibernate-configuration>
－－－－－－－－－－－－－－－－－－测试类代码如下：
package com.bjsxt.hibernate;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;
import org.hibernate.tool.hbm2ddl.SchemaExport;
import org.junit.AfterClass;
import org.junit.BeforeClass;
import org.junit.Test;

public class HibernateORMappingTest {
 private static SessionFactory sessionFactory;
 
 @BeforeClass
 public static void beforeClass() {
  new SchemaExport(new AnnotationConfiguration().configure()).create(false, true);
  sessionFactory = new AnnotationConfiguration().configure().buildSessionFactory();
 }
 @AfterClass
 public static void afterClass() {
  sessionFactory.close();
 }
 
 @Test
 public void testSaveUser() {
  User u = new User();
  u.setName("u1");
  Group g = new Group();
  g.setName("g1");
  u.setGroup(g);
  Session s = sessionFactory.getCurrentSession();
  s.beginTransaction();
  //s.save(g);
  s.save(u);
  s.getTransaction().commit();
 }
 
 @Test
 public void testSaveGroup() {
  User u1 = new User();
  u1.setName("u1");
  User u2 = new User();
  u2.setName("u2");
  Group g = new Group();
  g.setName("g1");
  g.getUsers().add(u1);
  g.getUsers().add(u2);
  u1.setGroup(g);
  u2.setGroup(g);
  Session s = sessionFactory.getCurrentSession();
  s.beginTransaction();
  //s.save(g);
  s.save(g);
  s.getTransaction().commit();
 }
 
 @Test
 public void testGetUser() {
  
  testSaveGroup();
  
  Session s = sessionFactory.getCurrentSession();
  s.beginTransaction();
  User u = (User)s.get(User.class, 1);
  System.out.println(u.getGroup().getName());
  s.getTransaction().commit();
  
 }
 
 @Test
 public void testLoadUser() {
  
  testSaveGroup();
  
  Session s = sessionFactory.getCurrentSession();
  s.beginTransaction();
  User u = (User)s.load(User.class, 1);
  System.out.println(u.getGroup().getName());
  s.getTransaction().commit();
  
 }
 
 @Test
 public void testDeleteUser() {
  
  testSaveGroup();
  
  Session s = sessionFactory.getCurrentSession();
  s.beginTransaction();
  //User u = (User)s.load(User.class, 1);
  //u.setGroup(null);
  //s.delete(u);
  s.createQuery("delete from User u where u.id = 1").executeUpdate();
  s.getTransaction().commit();
  
 }
 
 @Test
 public void testDeleteGroup() {
  
  testSaveGroup();
  
  Session s = sessionFactory.getCurrentSession();
  s.beginTransaction();
  //User u = (User)s.load(User.class, 1);
  //u.setGroup(null);
  //s.delete(u);
  Group g = (Group)s.load(Group.class, 1);
  s.delete(g);
  //s.createQuery("delete from User u where u.id = 1").executeUpdate();
  s.getTransaction().commit();
  
 }
 
 @Test
 public void testUpdateUser() {
  
  testSaveGroup();
  
  Session s = sessionFactory.getCurrentSession();
  s.beginTransaction();
  User u = (User)s.get(User.class, 1);
  
  s.getTransaction().commit();
  
  u.setName("user");
  u.getGroup().setName("group");
  
  Session s2 = sessionFactory.getCurrentSession();
  s2.beginTransaction();
  s2.update(u);
  
  s2.getTransaction().commit();
 }
 
 
 
 @Test
 public void testGetGroup() {
  
  testSaveGroup();
  
  Session s = sessionFactory.getCurrentSession();
  s.beginTransaction();
  Group g = (Group)s.get(Group.class, 1);
  s.getTransaction().commit();
  for(User u : g.getUsers()) {
   System.out.println(u.getName());
  }
 }
 
 @Test
 public void testSchemaExport() {
  new SchemaExport(new AnnotationConfiguration().configure()).create(false, true);
 }
 
 public static void main(String[] args) {
  beforeClass();
 }
}