使用Hibernate获取多列主键 [英] Using Hibernate Get with Multi-Column Primary Key

问题描述

假设我有一个如下所示的类：

  public class MyClass {
 @Id 
 @Column（name =ID）
私人长ID; 
} 
  

我可以使用hibernate会话来获取或加载类这个：

  MyClass a =（MyClass）session.get（MyClass.class，new Long（100））; 
  

然而，假设我有一个包含多个列的类作为主键：

  public MyJoinClass implements Serializable {
 private static final long serialVersionUID = -5L; 
 @Id 
 @Column（name =ID）
私人长ID; 
 
 @Id 
 @Column（name =EMAIL_ADDRESS_ID）
 private private emailAddressId; 
} 
  

是否可以使用get或load这样的类？

解决方案

尝试使用和 @IdClass 或 @EmbeddedId

  public MyJoinClass implements Serializable {
 private static final long serialVersionUID = -5L; 
 
 @EmbeddedId 
私人MyJoinClassKey键; 
 
 $ b $ public MyJoinClassKey实现Serializable {
 
 @Column（name =ID）
私有长ID; 
 
 @Column（name =EMAIL_ADDRESS_ID）
 private private emailAddressId; 
} 
  

然后使用

<$ MyJoinClass a =（MyJoinClass）session.get（MyJoinClass .class，new MyJoinClassKey（1，email））;

看看这个问题，这个被广义解释。基本上hibernate有一个复合键的机制。

Say I have a class that looks like this:

public class MyClass {
  @Id
  @Column(name = "ID")
  private long Id;
}

I can use a hibernate session to do a get or load on the class like this:

MyClass a = (MyClass)session.get(MyClass.class, new Long(100));

However, assume I have a class with multiple columns as the primary key:

public MyJoinClass implements Serializable {
  private static final long serialVersionUID = -5L;
  @Id
  @Column(name = "ID")
  private long id;

  @Id
  @Column(name = "EMAIL_ADDRESS_ID")
  private long emailAddressId;
}

Is it possible to use get or load with such a class?

解决方案

Try to use and @IdClass or @EmbeddedId

public MyJoinClass implements Serializable {
  private static final long serialVersionUID = -5L;

  @EmbeddedId
  private MyJoinClassKey key;
}

public MyJoinClassKey implements Serializable{

  @Column(name = "ID")
  private long id;

  @Column(name = "EMAIL_ADDRESS_ID")
  private long emailAddressId;
}

Then use

MyJoinClass a = (MyJoinClass )session.get(MyJoinClass .class, new MyJoinClassKey (1, "email"));

Take a look at this question, this is broadly explained. Basically hibernate have a mechanism for compound keys.

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