Hibernate5 映射，单向关联问题

上篇博客介绍了Hibernate相关配置问题，这片博客介绍Hibernate关联映射问题

一：单向映射，关联关系如图，可以看出tab_product表建立的外键factoryid，关联表tab_factory中的主键factoryid

用我上篇博客中用的tb_books表，添加字段factoryid，插入数据，关于mysql添加字段以及插入数据就不多说了，最后结果如图

创建tb_factory表，插入数据，结果如图：

二：建立Factory类：

package com.book.web3;

public class Factory {
	
	private int factoryid;
	private String name;
	
	public int getFactoryid(){
		return factoryid;
	}
	public void setFactoryid(int factoryid){
		this.factoryid = factoryid;
	}
	public String getName(){
		return name;
	}
	public void setName(String name){
		this.name = name;
	}	
}

在Book类中添加factory字段

package com.book.web3;

public class Book {
	public static int PAGE_SIZE = 2;	
	private int id;
	private String name;
	private double price;
	private int bookCount;
	private String author;
	private Factory factory;	
	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 double getPrice(){
		return price;
	}
	public void setPrice(double price){
		this.price = price;
	}
	
	public int getBookCount(){
		return bookCount;
	}
	public void setBookCount(int bookCount){
		this.bookCount = bookCount;
	}		
	public String getAuthor(){
		return author;
	}
	public void setAuthor(String author){
		this.author = author;
	}	
	public Factory getFactory(){
		return factory;
	}
	public void setFactory(Factory factory){
		this.factory = factory;
	}

}

三：在tb_books.hbm.xml中添加映射关系：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
    

<hibernate-mapping package="com.book.web3">
    <class name="Book" table="tb_books">
        <id name="id" column="id" type="int" >
            <generator class="assigned" />  <!--generator这个坑，如果指定class为native会导致外部程序设置的主键id无效，且根据数据库自行判断采用自增长式  -->
        </id>
        
        <property name="name" type="string">
            <column name="name"/>
        </property>
        <property name="price" type="double" column="price"></property>
		<property name="bookCount" type="int" column="bookCount"></property>
		<property name="author" type="string" column="author"></property>
		
		<many-to-one name="factory" class="com.book.web3.Factory">
		    <column name="factoryid"></column>
		</many-to-one>

    </class>
</hibernate-mapping>

创建tb_factory.hbm.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
    

<hibernate-mapping package="com.book.web3">
    <class name="Factory" table="tb_factory">
        <id name="factoryid" column="factoryid" type="int" >
            <generator class="assigned" />  <!--generator这个坑，如果指定class为native会导致外部程序设置的主键id无效，且根据数据库自行判断采用自增长式  -->
        </id>
        
        <property name="name" type="string">
            <column name="name"/>
        </property>
    </class>
</hibernate-mapping>

最后在hibernate.cfg.xml中配置tb_factory.hbm.xml这个文件

测试类中添加测试代码

	 public static void main(String[] args) {
//		 addData();
//		 queryData();
//		 deleteData();
//		 modifyData();
//		 twoCahce();
		 Relation();
     }	 
	 private static void  Relation(){
		 Session session = null;
		 try {
	  			session = HibernateUtil.getSession();
	  			session.beginTransaction();
	  			Book book = session.get(Book.class, new Integer("99"));
	  			System.out.print("产品ID：" + book.getId());
	  			System.out.print("产品名称：" + book.getName());
	  			System.out.print("产品价格：" + book.getPrice());
	  			System.out.print("产品数量：" + book.getBookCount());
	  			System.out.print("作者：" + book.getAuthor());
	  			System.out.print("factory：" + book.getFactory().getName());
	  			session.getTransaction().commit();
		 } catch (Exception e) {
			System.out.print("关联失败");
			e.printStackTrace();
		}finally{
			HibernateUtil.closeSession();
		}			 
	 } 

结果如图所示