hibernate能否实现非主键一对一关联

[laoqi1999]

大家好：

有两个表

A
{
id
name
...
rule_id
}

B
{
id
Name
...
rule_id
}

他们在数据库里没有任何关系，但是实际上他们是一对一的关系，根据rule_id 能确定。

请问hibernate能否实现这种对应关系，使得查出了A对象，从A对象能得到B对象？


谢谢！

[invoked]

不能

[greenbar]

可以

[laoqi1999]

具体怎么配置呢？

[不爱吃萝卜的兔子]

使用联合主键，primary key(A_id,B_id)试试

[youjianbo_han_87]

好像不行吧。

真的要用非主键关联的话，用原生 SQL吧。

[nianersmall]

建议这样的情况不要用一对一关联做约束限制，但非要做的话，可以尝试如下配置：

@Column(name = "rule_id", length = 36, nullable = false)
private String rule_id = "";

@OneToOne(cascade = CascadeType.ALL, optional = false)
@PrimaryKeyJoinColumn(name = "rule_id", referencedColumnName = "rule_id")
private B b = null;

声明，我也没测试过，不知道是否能够生效；

[nianersmall]

import java.io.Serializable;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToOne;
import javax.persistence.Table;

@Entity
@Table(name = "t_testa")
public class TestA implements Serializable
{
	private static final long serialVersionUID = 5474359037731558807L;

	@Id
	@Column(name = "id", length = 36, nullable = false)
	private String id = "";

	@Column(name = "name", length = 50, nullable = false)
	private String name = "";

	@OneToOne(cascade = CascadeType.ALL, optional = false)
	@JoinColumn(name = "testa_id", referencedColumnName = "testb_id")
	private TestB testB = null;

	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;
	}

	public TestB getTestB()
	{
		return testB;
	}

	public void setTestB(TestB testB)
	{
		this.testB = testB;
	}

	@Override
	public int hashCode()
	{
		final int prime = 31;
		int result = 1;
		result = prime * result + ((id == null) ? 0 : id.hashCode());
		return result;
	}

	@Override
	public boolean equals(Object obj)
	{
		if (this == obj)
			return true;
		if (obj == null)
			return false;
		if (getClass() != obj.getClass())
			return false;
		TestA other = (TestA) obj;
		if (id == null)
		{
			if (other.id != null)
				return false;
		}
		else if (!id.equals(other.id))
			return false;
		return true;
	}
}

import java.io.Serializable;

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

@Entity
@Table(name = "t_testb")
public class TestB implements Serializable
{
	private static final long serialVersionUID = -5227555122162835236L;

	@Id
	@Column(name = "id", length = 36, nullable = false)
	private String id = "";

	@Column(name = "name", length = 50, nullable = false)
	private String name = "";

	@Column(name = "testb_id", length = 36, nullable = false)
	private String testb_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;
	}

	public String getTestb_id()
	{
		return testb_id;
	}

	public void setTestb_id(String testbId)
	{
		testb_id = testbId;
	}

	@Override
	public int hashCode()
	{
		final int prime = 31;
		int result = 1;
		result = prime * result + ((id == null) ? 0 : id.hashCode());
		return result;
	}

	@Override
	public boolean equals(Object obj)
	{
		if (this == obj)
			return true;
		if (obj == null)
			return false;
		if (getClass() != obj.getClass())
			return false;
		TestB other = (TestB) obj;
		if (id == null)
		{
			if (other.id != null)
				return false;
		}
		else if (!id.equals(other.id))
			return false;
		return true;
	}
}

测试通过

[youjianbo_han_87]

学习。

[liguominz]

mark

[rambosir]

使用hibernate<one-to-one>外键关联映射吧

[haojia0716]

如果在数据库里没有关系 那你就在逻辑代码里写关系 因为你知道关系

如果要在数据库里建立一对一关联 可以用one-to-one
一般用many-to-one + unique

[laoqi1999]

谢谢各位，我在hbm文件里把rule_id当做主键，1对1关联。