one-to-one双向关联之加载 - 数据库编程

关于hibernate的加载方式有两种，一种是get加载，一种是load加载，load属于延迟加载，使用了动态代理。这不是我们所关心的，我们看一看一对一双向关联在加载时有什么特点，想要观察特点，不得不看hibernate为我们生成的sql语句。

husband类与上一篇没有变化如下：

/**
 * 
 */
package com.maybe.test_1;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToOne;
import javax.persistence.Table;

/**
 * @author MayBe
 *
 * function:
 */
@Entity
@Table(name="t_husband")
public class Husband {
	
	private Integer id;
	private String name;
	private Wife wife;
	@Id
	@GeneratedValue
	public Integer getId() {
		return id;
	}
	
	public String getName() {
		return name;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	public void setName(String name) {
		this.name = name;
	}

	@OneToOne(mappedBy="husband")
	public Wife getWife() {
		return wife;
	}

	public void setWife(Wife wife) {
		this.wife = wife;
	}
	

}

wife类也没有变化：

/**
 * 
 */
package com.maybe.test_1;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToOne;
import javax.persistence.Table;

/**
 * @author MayBe
 *
 * function:
 */
@Entity
@Table(name="t_wife")
public class Wife {
	
	private Integer id;
	private String name;
	private Husband husband;
	@Id
	@GeneratedValue
	public Integer getId() {
		return id;
	}
	public String getName() {
		return name;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	public void setName(String name) {
		this.name = name;
	}
	@OneToOne
	public Husband getHusband() {
		return husband;
	}
	public void setHusband(Husband husband) {
		this.husband = husband;
	}
	

}

junit测试方法如下：

@Test
	public void One_to_oneLoadTest1(){
		//一对一双向关联

		Session s = sessionFacotry.getCurrentSession();
		
		s.beginTransaction();
		
		Husband hus = (Husband)s.get(Husband.class, 2);	

                System.out.println("*****************");
				
		Wife wif = (Wife)s.get(Wife.class, 3);


		s.getTransaction().commit();
	
	}

假设我们在数据中存在一个id为2的husband，他与id为2的wife是关联的。在数据库有一个id为3的wife，她与id为3的husband是关联的，我们运行一下这个测试，输出sql语句如下：

2014-02-04 16:52:20 INFO org.hibernate.tool.hbm2ddl.SchemaUpdate:182 - HHH000228: Running hbm2ddl schema update
   2014-02-04 16:52:20 INFO org.hibernate.tool.hbm2ddl.SchemaUpdate:193 - HHH000102: Fetching database metadata
   2014-02-04 16:52:20 INFO org.hibernate.tool.hbm2ddl.SchemaUpdate:205 - HHH000396: Updating schema
   2014-02-04 16:52:21 INFO org.hibernate.tool.hbm2ddl.TableMetadata:66 - HHH000261: Table found: hibernate.dbo.t_husband
   2014-02-04 16:52:21 INFO org.hibernate.tool.hbm2ddl.TableMetadata:67 - HHH000037: Columns: [id, name]
   2014-02-04 16:52:21 INFO org.hibernate.tool.hbm2ddl.TableMetadata:69 - HHH000108: Foreign keys: []
   2014-02-04 16:52:21 INFO org.hibernate.tool.hbm2ddl.TableMetadata:70 - HHH000126: Indexes: [pk__t_husban__3213e83f0f624af8]
   2014-02-04 16:52:21 INFO org.hibernate.tool.hbm2ddl.TableMetadata:66 - HHH000261: Table found: hibernate.dbo.t_wife
   2014-02-04 16:52:21 INFO org.hibernate.tool.hbm2ddl.TableMetadata:67 - HHH000037: Columns: [id, husba

one-to-one双向关联之加载(一)