java Hibernate - TypedQuery.getResultList() 返回相同对象的列表

Hibernate - TypedQuery.getResultList() returns a list of the same object

提问by Francesco

Here is a more and maybe better description of the problem:

这是对问题的更多甚至更好的描述：

I do a simple select query. The returning list contains the exact number of records/objects as if I do the same query in the DB, but the problem is that all the objects are the same/identical.

我做了一个简单的选择查询。返回列表包含准确数量的记录/对象，就像我在数据库中执行相同的查询一样，但问题是所有对象都相同/相同。

For ex, this is the result in the DB (I removed the null values):
26801 01-JAN-00 7 31-DEC-99 7 Obere Kirchstr. 26 CH 8304 Walliselln
26801 01-JAN-00 2 31-DEC-99 2 Obere Kirchstr. 26 CH 8304 Walliselln

例如，这是数据库中的结果（我删除了空值）：
26801 01-JAN-00 7 31-DEC-99 7 Obere Kirchstr。26 CH 8304 Walliselln
26801 01-JAN-00 2 31-DEC-99 2 Obere Kirchstr. 26 CH 8304 瓦利塞恩

And this is the content of the variable addresses as I can see it in Eclipse during the debugging after the query has been executed:

这是我在 Eclipse 中在执行查询后调试期间可以看到的变量地址的内容：

addresses ArrayList (id=81)
elementData Object[10] (id=86)
[0] DLDBAddress (id=82)
[1] DLDBAddress (id=82)
[2] null
...
modCount 1
size 2

地址 ArrayList (id=81)
elementData Object[10] (id=86)
[0] DLDBAddress (id=82)
[1] DLDBAddress (id=82)
[2] null
...
modCount 1
size 2

DLDBAddress [persid=26801, valPeriodStart=1900-01-01, valPeriodEnd=9999-12-31, addressNr=7, addressType=7, addressRow1=null, addressRow2=Obere Kirchstr. 26, addressRow3=null, country=CH , postalCode=8304, city=Walliselln, phoneNr=null, faxNr=null, sekretaryPhoneNr=null, alternatPhoneNr=null, pagerNr=null]

DLDBAddress [persid=26801，valPeriodStart=1900-01-01，valPeriodEnd=9999-12-31，addressNr=7，addressType=7，addressRow1=null，addressRow2=Obere Kirchstr。26、addressRow3=null、country=CH、postalCode=8304、city=Walliselln、phoneNr=null、faxNr=null、sekretaryPhoneNr=null、alternatPhoneNr=null、pagerNr=null]

DLDBAddress [persid=26801, valPeriodStart=1900-01-01, valPeriodEnd=9999-12-31, addressNr=7, addressType=7, addressRow1=null, addressRow2=Obere Kirchstr. 26, addressRow3=null, country=CH , postalCode=8304, city=Walliselln, phoneNr=null, faxNr=null, sekretaryPhoneNr=null, alternatPhoneNr=null, pagerNr=null]]

DLDBAddress [persid=26801，valPeriodStart=1900-01-01，valPeriodEnd=9999-12-31，addressNr=7，addressType=7，addressRow1=null，addressRow2=Obere Kirchstr。26、addressRow3=null、country=CH、postalCode=8304、city=Walliselln、phoneNr=null、faxNr=null、sekretaryPhoneNr=null、alternatPhoneNr=null、pagerNr=null]]

As you can see, the two objects are identical. They shoul instead differ from the addressNr and addressType...

如您所见，这两个对象是相同的。它们应该与 addressNr 和 addressType 不同......

This is the piece of code where I build up the query:

这是我构建查询的代码段：

public static <T> List<T> findBy(EntityManager eM, Class<T> boClass, String whereClause, String whereValue)  
 {
    EntityManager entityManager = eM;
    Query query = entityManager.createQuery("from " + boClass.getName() + " s where s." + whereClause + " = " + whereValue);
    ...
    return (List<T>) query.getResultList();
}

and this is the (quite simple) resulting query:

这是（非常简单）结果查询：

from ch.ethz.id.wai.pdb.bo.DLDBAddress s where s.persid = 26801

来自 ch.ethz.id.wai.pdb.bo.DLDBAddress s 其中 s.persid = 26801

This is the generated query:

这是生成的查询：

Hibernate: 
select
dldbaddres0_.PERSID as PERSID0_,
dldbaddres0_.ADRNUM as ADRNUM0_,
dldbaddres0_.ADRZEIL1 as ADRZEIL3_0_,
dldbaddres0_.ADRZEIL2 as ADRZEIL4_0_,
dldbaddres0_.ADRZEIL3 as ADRZEIL5_0_,
dldbaddres0_.ADRTYP as ADRTYP0_,
dldbaddres0_.ADRAUSWTEL as ADRAUSWTEL0_,
dldbaddres0_.ADRORT as ADRORT0_,
dldbaddres0_.ADRLAND as ADRLAND0_,
dldbaddres0_.ADRFAX as ADRFAX0_,
dldbaddres0_.ADRPSA as ADRPSA0_,
dldbaddres0_.ADRTEL as ADRTEL0_,
dldbaddres0_.ADRPLZ as ADRPLZ0_,
dldbaddres0_.ADRSEKTEL as ADRSEKTEL0_,
dldbaddres0_.BISDAT as BISDAT0_,
dldbaddres0_.VONDAT as VONDAT0_ 
from
NETHZ.V_DLDB_ADRESSE dldbaddres0_ 
where
dldbaddres0_.PERSID=26801

And here the entity:

这里是实体：

@Entity
@Table(name = "V_DLDB_ADRESSE", schema="NETHZ")
public class DLDBAddress
{
  @Id
  @Column(name = "PERSID", insertable = false, updatable = false)
  private Integer   persid;
  @Temporal(TemporalType.DATE)
  @Column(name = "VONDAT", insertable = false, updatable = false)
  private Date   valPeriodStart;
  @Temporal(TemporalType.DATE)
  @Column(name = "BISDAT", insertable = false, updatable = false)
  private Date   valPeriodEnd;
  @Column(name = "ADRNUM", insertable = false, updatable = false)
  private Integer addressNr;
  @Column(name = "ADRTYP", insertable = false, updatable = false)
  private Integer addressType;
  @Column(name = "ADRZEIL1", insertable = false, updatable = false)
  private String addressRow1;
  @Column(name = "ADRZEIL2", insertable = false, updatable = false)
  private String addressRow2;
  @Column(name = "ADRZEIL3", insertable = false, updatable = false)
  private String addressRow3;
  @Column(name = "ADRLAND", insertable = false, updatable = false)
  private String country;
  @Column(name = "ADRPLZ", insertable = false, updatable = false)
  private String postalCode;
  @Column(name = "ADRORT", insertable = false, updatable = false)
  private String city;
  @Column(name = "ADRTEL", insertable = false, updatable = false)
  private String phoneNr;
  @Column(name = "ADRFAX", insertable = false, updatable = false)
  private String faxNr;
  @Column(name = "ADRSEKTEL", insertable = false, updatable = false)
  private String secretaryPhoneNr;
  @Column(name = "ADRAUSWTEL", insertable = false, updatable = false)
  private String alternatPhoneNr;
  @Column(name = "ADRPSA", insertable = false, updatable = false)
  private String pagerNr;

...

Am I missing something?

我错过了什么吗？

Ah, I'm connecting to an Oracle DB.

啊，我正在连接到 Oracle DB。

Thanks in advance Francesco

在此先感谢弗朗西斯科

回答by Vladimir Dyuzhev

where dldbaddres0_.PERSID=26801

@Id
  @Column(name = "PERSID", insertable = false, updatable = false)

You defined PERSID as @Id, which is a primary key. Is it really unique for your application? From the behavior it is not. But for Hib it MUST be.

您将 PERSID 定义为 @Id，它是一个主键。它对您的应用来说真的是独一无二的吗？从行为上看不是。但对于 Hib 来说，它必须是。

So what happens:

那么会发生什么：

1. You have two+ records in the database with PERSID = 26801
2. You query them WHERE PERSID=26801
3. SQL Query returns two+ rows
4. Hib loads first one, and puts into session, with PERSID as a key (because it is marked as @Id). Object is placed into the result list.
5. Hib loads second one, notices that an object with same @Id is already in the session, and just places the reference into the result List. Row data are ignored.
6. Thus you get two+ copies.

1. 您在数据库中有两条以上的记录，PERSID = 26801
2. 你查询他们 WHERE PERSID=26801
3. SQL 查询返回两行以上
4. Hib 加载第一个，并进入会话，以 PERSID 作为键（因为它被标记为 @Id）。对象被放入结果列表。
5. Hib 加载第二个，注意到会话中已经有一个具有相同@Id 的对象，然后将引用放入结果列表中。行数据被忽略。
6. 因此你会得到两个以上的副本。