使用@LazyToOne进行Hibernate延迟加载（LazyToOneOption.NO_PROXY） [英] Hibernate Lazy Loading with @LazyToOne(LazyToOneOption.NO_PROXY)
问题描述
我有一个在JBoss AS 7.2上运行Hibernate 4.2.21的应用程序
I have an app running Hibernate 4.2.21 on JBoss AS 7.2
我们目前有一些@OneToOne关系，由于已知的延迟加载限制，总是急切地反向获取。
We currently have a few @OneToOne relationships which, due to known limitations of lazy loading, will alway fetch eagerly on the inverse side.
为了启用反向关系的延迟加载，我试图启用构建时字节码检测。
In order to enable Lazy loading for inverse relationships I am trying to enable build-time bytecode instrumentation.
这就是我的意思到目前为止已完成...
Here's what I've done so far...
1）使用 maven-antrun-plugin 激活检测（我尝试了hibernate -enhance-maven-plugin并且无法使其工作，但那是另一个问题），我现在在构建日志中获得以下maven输出：
1) Activate instrumentation using maven-antrun-plugin (I tried the hibernate-enhance-maven-plugin and couldn't get it working but thats for another question), I now get the following maven output in the build log:
[INFO] --- maven-antrun-plugin:1.7:run (Instrument domain classes) @ MyApp-entities ---
[INFO] Executing tasks
instrument:
[instrument] starting instrumentation
[INFO] Executed tasks
2）接下来，我将所有@OneToOne关系注释如下......
2) Next I annotated all @OneToOne relationships as follows...
@OneToOne(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy = "client", optional=false)
@LazyToOne(LazyToOneOption.NO_PROXY)
public ClientPrefs getClientPrefs() {
return clientPrefs;
}
public void setClientPrefs(ClientPrefs clientPrefs) {
this.clientPrefs = clientPrefs;
}
3）然后我添加实现FieldHandled 到@Entity类以及私有字段和getter和setter：
3) Then I add implement FieldHandled to the @Entity classes along with private field and getter and setter:
private FieldHandler fieldHandler;
成功...我现在在部署日志中获得以下输出：
success...I am now getting following output in the deployment log:
15:54:09,720 INFO [org.hibernate.tuple.entity.EntityMetamodel] (ServerService Thread Pool -- 56) HHH000157: Lazy property fetching available for: uk.co.myapp.entities.Session
15:54:09,730 INFO [org.hibernate.tuple.entity.EntityMetamodel] (ServerService Thread Pool -- 57) HHH000157: Lazy property fetching available for: uk.co.myapp.entities.Session
15:54:09,969 INFO [org.hibernate.tuple.entity.EntityMetamodel] (ServerService Thread Pool -- 56) HHH000157: Lazy property fetching available for: uk.co.myapp.entities.Client
15:54:09,970 INFO [org.hibernate.tuple.entity.EntityMetamodel] (ServerService Thread Pool -- 57) HHH000157: Lazy property fetching available for: uk.co.myapp.entities.Client
15:54:09,999 INFO [org.hibernate.tuple.entity.EntityMetamodel] (ServerService Thread Pool -- 56) HHH000157: Lazy property fetching available for: uk.co.myapp.entities.Country
15:54:10,003 INFO [org.hibernate.tuple.entity.EntityMetamodel] (ServerService Thread Pool -- 57) HHH000157: Lazy property fetching available for: uk.co.myapp.entities.Country
15:54:10,054 INFO [org.hibernate.tuple.entity.EntityMetamodel] (ServerService Thread Pool -- 56) HHH000157: Lazy property fetching available for: uk.co.myapp.entities.Pool
15:54:10,054 INFO [org.hibernate.tuple.entity.EntityMetamodel] (ServerService Thread Pool -- 57) HHH000157: Lazy property fetching available for: uk.co.myapp.entities.Pool
15:54:10,569 INFO [org.hibernate.tuple.entity.EntityMetamodel] (ServerService Thread Pool -- 56) HHH000157: Lazy property fetching available for: uk.co.myapp.entities.User
15:54:10,624 INFO [org.hibernate.tuple.entity.EntityMetamodel] (ServerService Thread Pool -- 57) HHH000157: Lazy property fetching available for: uk.co.myapp.entities.User
现在关系不再急切加载......但是他们也没有延迟加载，他们只是默默地返回null。
The relationships now no longer eagerly load...but they don't lazy load either, they just return null silently.
我试过删除 FieldHandled 界面来自实体的 FieldHandler 字段，因为我不确定是否有必要，之后我不再获得'HHH000157：Lazy property fetching available for ：'在启动时消息，它会在默认情况下回到急切加载状态。
I have tried removing the FieldHandled interface and FieldHandler field from the Entity as I was not sure if this was necessary, after this I no longer get the 'HHH000157: Lazy property fetching available for:'message at startup and it goes back to eagerly loading by default.
我在这里遗漏了什么吗？ hibernate文档没有明确说明如何实际设置它
Am I missing something here? The hibernate docs are not explicit on how to actually set this up
编辑：根据评论添加了Ant任务配置：
Added the Ant task config as per comments:
<build>
<plugins>
<plugin>
<artifactId>maven-antrun-plugin</artifactId>
<version>1.7</version>
<executions>
<execution>
<phase>process-classes</phase>
<id>Instrument domain classes</id>
<configuration>
<target name="instrument">
<taskdef name="instrument"
classname="org.hibernate.tool.instrument.javassist.InstrumentTask">
<classpath>
<path refid="maven.dependency.classpath" />
<path refid="maven.plugin.classpath" />
</classpath>
</taskdef>
<instrument verbose="true">
<fileset dir="${project.build.outputDirectory}">
<include name="MyApp-entities/co/uk/myapp/entities/*.class" />
</fileset>
</instrument>
</target>
</configuration>
<goals>
<goal>run</goal>
</goals>
</execution>
</executions>
<dependencies>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-core</artifactId>
<version>4.2.21.Final</version>
</dependency>
<dependency>
<groupId>org.javassist</groupId>
<artifactId>javassist</artifactId>
<version>3.18.1-GA</version>
</dependency>
</dependencies>
</plugin>
</plugins>
</build>
推荐答案
像往常一样，这是配置问题，似乎ant运行插件需要指向包含实体而不是父目录之一的确切目录
As usual it was a configuration issue, it seems that the ant run plugin needs to be pointed to an exact directory that contains the entities rather than one of the parent directories
这对我有用...
<instrument verbose="true">
<fileset dir="${project.build.directory}/classes/uk/co/myapp/entities">
<include name="*.class" />
</fileset>
</instrument>
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