hibernate集合映射，one-to-many,删除集合成员

最新推荐文章于 2018-01-28 13:47:16 发布

joyyq

最新推荐文章于 2018-01-28 13:47:16 发布

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分类专栏： hibernate 文章标签： hibernate myeclipse class session string generator

本文链接：https://blog.youkuaiyun.com/joyyq/article/details/7359098

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本文详细介绍了在Hibernate中如何处理one-to-many集合映射，包括映射文件配置、模型类定义以及使用Hibernate工具类进行增删改查操作。通过JUnit测试代码展示了如何删除集合中的成员并更新实体。

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1、one方映射文件

<?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="com.epro.examsys.model.Department" table="t_department" catalog="edu">
        <id name="id" type="java.lang.Integer">
            <column name="id" />
            <generator class="native" />
        </id>
        <property name="name" type="java.lang.String">
            <column name="departName" not-null="true" />
        </property>
        <set name="emps" lazy="false" inverse="true" cascade="save-update, delete,delete-orphan">
        <key>
            <column name="depart_id"></column>
        </key>
            <one-to-many class="com.epro.examsys.model.Employee"/>
        </set>
    </class>
</hibernate-mapping>

2、many方映射文件

<?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="com.epro.examsys.model.Employee" table="t_employee" catalog="edu">
        <id name="id" type="java.lang.Integer">
            <column name="id" />
            <generator class="native" />
        </id>
        <property name="name" type="java.lang.String">
            <column name="empName" not-null="true" />
        </property>
        <many-to-one name="depart" column="depart_id" class="com.epro.examsys.model.Department" lazy="false">
        </many-to-one>
    </class>
</hibernate-mapping>

3、one方model文件

package com.epro.examsys.model;

import java.util.Set;

public class Department {
private int id;
private Set<Employee> emps;
public Set<Employee> getEmps() {
  return emps;
}
public void setEmps(Set<Employee> emps) {
  this.emps = emps;
}
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;
}
private String name;
}

4、many方model文件

package com.epro.examsys.model;

public class Employee {
private int id;
private String name;
private Department depart;
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;
}
public Department getDepart() {
  return depart;
}
public void setDepart(Department depart) {
  this.depart = depart;
}
}

5、Hibernate工具类

package com.epro.examsys.util;

import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;

public final class HibernateUtil {
private static SessionFactory sessionFactory;
private HibernateUtil(){

}

static
{
  Configuration cfg = new Configuration();
  cfg.configure();//加载classpath中的hibernate配置文件hibernate.cfg.xml
  sessionFactory = cfg.buildSessionFactory();
}

public static SessionFactory getSessionFactory()
{
  return sessionFactory;
}

public static Session getSession(){
  return sessionFactory.openSession();
}

static void add(Object obj)
{
  Session s = null;
  Transaction tx = null;
  try{
   s = HibernateUtil.getSession();
   tx = s.beginTransaction();
   s.save(obj);
   tx.commit();
  }catch(HibernateException ex){
   if(tx!=null)
    tx.rollback();
   ex.printStackTrace();
   throw ex;
  }finally{
   if(null!=s)
    s.close();
  }
}

static void del(Object obj)
{
  Session s = null;
  Transaction tx = null;
  try{
   s = HibernateUtil.getSession();
   tx = s.beginTransaction();
   s.delete(obj);
   tx.commit();
  }catch(HibernateException ex){
   if(tx!=null)
    tx.rollback();
   ex.printStackTrace();
   throw ex;
  }finally{
   if(null!=s)
    s.close();
  }
}

static void update(Object obj)
{
  Session s = null;
  Transaction tx = null;
  try{
   s = HibernateUtil.getSession();
   tx = s.beginTransaction();
   s.update(obj);
   tx.commit();
  }catch(HibernateException ex){
   if(tx!=null)
    tx.rollback();
   ex.printStackTrace();
   throw ex;
  }finally{
   if(null!=s)
    s.close();
  }
}
}

6、junit测试代码

@Test
public void testSaveOrUpdateDepartment(){
  Session s = null;
  Transaction tx = null;
  try
  {
   s = HibernateUtil.getSessionFactory().openSession();
   tx = s.beginTransaction();
   Department depart = (Department) s.get(Department.class, 2);
   Employee e = depart.getEmps().iterator().next();
   System.out.println("begin:"+depart.getEmps().size());
   depart.getEmps().remove(e);
   depart.setName("hahaha...");
   System.out.println("end:"+depart.getEmps().size());
   tx.commit();
   Assert.assertTrue(true);
  }catch(HibernateException hEX){
   hEX.printStackTrace();
   if(tx!=null)
    tx.rollback();
   Assert.assertFalse(false);
  }
  finally
  {
   if(s!=null)
    s.close();
  }
}