Address 和 person 是多对一的关系，比如:
人:
@Id
@Column(name="personid")
private Long personId;
private String firstName;
private String lastName;
private String email;
@OneToMany(cascade = CascadeType.ALL,mappedBy="person",targetEntity=Address.class,fetch=FetchType.LAZY)
private List addressArray=new ArrayList<>();
public Person() {
}
和地址:
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name="personId")
private Person person;
我想从地址对象(如“address.person.firstname”)访问人的名字，但它总是急切地加载人？
我还尝试使用我的 pom.xml 包含的 Maven 对其进行静态编织:
<plugins>
<artifactId>maven-antrun-plugin</artifactId>
<executions>
<execution>
<phase>process-classes</phase>
<configuration>
<tasks>
<java classname="org.eclipse.persistence.tools.weaving.jpa.StaticWeave"
classpathref="maven.runtime.classpath" fork="true">
<arg line="-loglevel FINE -persistenceinfo src target/classes target/classes"/>
</java>
</tasks>
</configuration>
<goals>
<goal>run</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
还添加了 <property name="eclipselink.weaving" value="static"/>在 persistence.xml 中
我也尝试过动态编织，但它给出了异常(exception):
java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at sun.instrument.InstrumentationImpl.loadClassAndStartAgent(InstrumentationImpl.java:382)
at sun.instrument.InstrumentationImpl.loadClassAndCallPremain(InstrumentationImpl.java:397)
Caused by: java.lang.NoClassDefFoundError: javax/persistence/spi/PersistenceUnitInfo
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:186)
at org.eclipse.persistence.internal.jpa.deployment.JavaSECMPInitializerAgent.initializeFromAgent(JavaSECMPInitializerAgent.java:44)
at org.eclipse.persistence.internal.jpa.deployment.JavaSECMPInitializerAgent.premain(JavaSECMPInitializerAgent.java:39)
... 6 more
Caused by: java.lang.ClassNotFoundException: javax.persistence.spi.PersistenceUnitInfo
at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:423)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
... 10 more
FATAL ERROR in native method: processing of -javaagent failed
Exception in thread "main"
我的静态编织类文件显示了以下方法但仍然不起作用:
当 weaving=static 和 logging = FINEST 时，请在编织后检查我的日志
[EL Finest]: jpa: 2013-09-26 18:07:40.453--ServerSession(8941730)--Thread(Thread[main,5,main])--Begin predeploying Persistence Unit TestDB; session file:/C:/Users/achyut_anr/achyut_anr/CheckWeaving/bin/_TestDB; state Initial; factoryCount 0
[EL Finest]: properties: 2013-09-26 18:07:40.475--ServerSession(8941730)--Thread(Thread[main,5,main])--property=eclipselink.orm.throw.exceptions; default value=true
[EL Finest]: properties: 2013-09-26 18:07:40.475--ServerSession(8941730)--Thread(Thread[main,5,main])--property=eclipselink.weaving.changetracking; default value=true
[EL Finest]: properties: 2013-09-26 18:07:40.476--ServerSession(8941730)--Thread(Thread[main,5,main])--property=eclipselink.weaving.lazy; default value=true
[EL Finest]: properties: 2013-09-26 18:07:40.476--ServerSession(8941730)--Thread(Thread[main,5,main])--property=eclipselink.weaving.eager; default value=false
[EL Finest]: properties: 2013-09-26 18:07:40.476--ServerSession(8941730)--Thread(Thread[main,5,main])--property=eclipselink.weaving.fetchgroups; default value=true
[EL Finest]: properties: 2013-09-26 18:07:40.476--ServerSession(8941730)--Thread(Thread[main,5,main])--property=eclipselink.weaving.internal; default value=true
[EL Finest]: properties: 2013-09-26 18:07:40.476--ServerSession(8941730)--Thread(Thread[main,5,main])--property=eclipselink.weaving.rest; default value=true
[EL Finest]: properties: 2013-09-26 18:07:40.477--ServerSession(8941730)--Thread(Thread[main,5,main])--property=eclipselink.multitenant.tenants-share-emf; default value=true
[EL Finest]: properties: 2013-09-26 18:07:40.478--ServerSession(8941730)--Thread(Thread[main,5,main])--property=eclipselink.multitenant.tenants-share-cache; default value=false
[EL Finer]: metadata: 2013-09-26 18:07:40.496--ServerSession(8941730)--Thread(Thread[main,5,main])--Searching for default mapping file in file:/C:/Users/achyut_anr/achyut_anr/CheckWeaving/bin/ (There is no English translation for this message.)
[EL Finer]: metadata: 2013-09-26 18:07:40.5--ServerSession(8941730)--Thread(Thread[main,5,main])--Searching for default mapping file in file:/C:/Users/achyut_anr/achyut_anr/CheckWeaving/bin/ (There is no English translation for this message.)
[EL Config]: metadata: 2013-09-26 18:07:40.681--ServerSession(8941730)--Thread(Thread[main,5,main])--The access type for the persistent class [class com.altametrics.persistence.services.Address] is set to [FIELD].
[EL Config]: metadata: 2013-09-26 18:07:40.723--ServerSession(8941730)--Thread(Thread[main,5,main])--The target entity (reference) class for the many to one mapping element [field person] is being defaulted to: class com.altametrics.persistence.services.Person.
[EL Config]: metadata: 2013-09-26 18:07:40.725--ServerSession(8941730)--Thread(Thread[main,5,main])--The access type for the persistent class [class com.altametrics.persistence.services.Person] is set to [FIELD].
[EL Config]: metadata: 2013-09-26 18:07:40.733--ServerSession(8941730)--Thread(Thread[main,5,main])--The alias name for the entity class [class com.altametrics.persistence.services.Address] is being defaulted to: Address.
[EL Config]: metadata: 2013-09-26 18:07:40.735--ServerSession(8941730)--Thread(Thread[main,5,main])--The table name for entity [class com.altametrics.persistence.services.Address] is being defaulted to: ADDRESS.
[EL Config]: metadata: 2013-09-26 18:07:40.759--ServerSession(8941730)--Thread(Thread[main,5,main])--The column name for element [id] is being defaulted to: ID.
[EL Config]: metadata: 2013-09-26 18:07:40.761--ServerSession(8941730)--Thread(Thread[main,5,main])--The column name for element [addressLine2] is being defaulted to: ADDRESSLINE2.
[EL Config]: metadata: 2013-09-26 18:07:40.762--ServerSession(8941730)--Thread(Thread[main,5,main])--The column name for element [addressLine1] is being defaulted to: ADDRESSLINE1.
[EL Config]: metadata: 2013-09-26 18:07:40.762--ServerSession(8941730)--Thread(Thread[main,5,main])--The alias name for the entity class [class com.altametrics.persistence.services.Person] is being defaulted to: Person.
[EL Config]: metadata: 2013-09-26 18:07:40.762--ServerSession(8941730)--Thread(Thread[main,5,main])--The table name for entity [class com.altametrics.persistence.services.Person] is being defaulted to: PERSON.
[EL Config]: metadata: 2013-09-26 18:07:40.763--ServerSession(8941730)--Thread(Thread[main,5,main])--The column name for element [id] is being defaulted to: ID.
[EL Config]: metadata: 2013-09-26 18:07:40.763--ServerSession(8941730)--Thread(Thread[main,5,main])--The column name for element [lastName] is being defaulted to: LASTNAME.
[EL Config]: metadata: 2013-09-26 18:07:40.763--ServerSession(8941730)--Thread(Thread[main,5,main])--The column name for element [email] is being defaulted to: EMAIL.
[EL Config]: metadata: 2013-09-26 18:07:40.764--ServerSession(8941730)--Thread(Thread[main,5,main])--The column name for element [firstName] is being defaulted to: FIRSTNAME.
[EL Config]: metadata: 2013-09-26 18:07:40.785--ServerSession(8941730)--Thread(Thread[main,5,main])--The primary key column name for the mapping element [field person] is being defaulted to: ID.
[EL Finer]: weaver: 2013-09-26 18:07:40.805--ServerSession(8941730)--Thread(Thread[main,5,main])--Class [com.altametrics.persistence.services.Address] registered to be processed by weaver.
[EL Finer]: weaver: 2013-09-26 18:07:40.807--ServerSession(8941730)--Thread(Thread[main,5,main])--Class [com.altametrics.persistence.services.Person] registered to be processed by weaver.
[EL Finest]: jpa: 2013-09-26 18:07:40.809--ServerSession(8941730)--Thread(Thread[main,5,main])--End predeploying Persistence Unit TestDB; session file:/C:/Users/achyut_anr/achyut_anr/CheckWeaving/bin/_TestDB; state Predeployed; factoryCount 0
[EL Finer]: weaver: 2013-09-26 18:07:40.81--Thread(Thread[main,5,main])--JavaSECMPInitializer - transformer is null.
[EL Finest]: jpa: 2013-09-26 18:07:40.81--ServerSession(8941730)--Thread(Thread[main,5,main])--Begin predeploying Persistence Unit TestDB; session file:/C:/Users/achyut_anr/achyut_anr/CheckWeaving/bin/_TestDB; state Predeployed; factoryCount 0
[EL Finest]: jpa: 2013-09-26 18:07:40.81--ServerSession(8941730)--Thread(Thread[main,5,main])--End predeploying Persistence Unit TestDB; session file:/C:/Users/achyut_anr/achyut_anr/CheckWeaving/bin/_TestDB; state Predeployed; factoryCount 1
[EL Finest]: jpa: 2013-09-26 18:07:40.815--ServerSession(8941730)--Thread(Thread[main,5,main])--Begin deploying Persistence Unit TestDB; session file:/C:/Users/achyut_anr/achyut_anr/CheckWeaving/bin/_TestDB; state Predeployed; factoryCount 1
[EL Finer]: 2013-09-26 18:07:40.829--ServerSession(8941730)--Thread(Thread[main,5,main])--Could not initialize Validation Factory. Encountered following exception: java.lang.NoClassDefFoundError: javax/validation/Validation
[EL Finest]: properties: 2013-09-26 18:07:40.831--ServerSession(8941730)--Thread(Thread[main,5,main])--property=eclipselink.logging.level; value=FINEST; translated value=FINEST
[EL Finest]: properties: 2013-09-26 18:07:40.832--ServerSession(8941730)--Thread(Thread[main,5,main])--property=eclipselink.logging.level; value=FINEST; translated value=FINEST
[EL Finest]: properties: 2013-09-26 18:07:40.837--ServerSession(8941730)--Thread(Thread[main,5,main])--property=javax.persistence.jdbc.user; value=root
[EL Finest]: properties: 2013-09-26 18:07:40.837--ServerSession(8941730)--Thread(Thread[main,5,main])--property=javax.persistence.jdbc.password; value=xxxxxx
[EL Finest]: properties: 2013-09-26 18:07:41.502--ServerSession(8941730)--Thread(Thread[main,5,main])--property=javax.persistence.jdbc.driver; value=com.mysql.jdbc.Driver
[EL Finest]: properties: 2013-09-26 18:07:41.502--ServerSession(8941730)--Thread(Thread[main,5,main])--property=javax.persistence.jdbc.url; value=jdbc:mysql://localhost:3306/sample
[EL Info]: 2013-09-26 18:07:41.506--ServerSession(8941730)--Thread(Thread[main,5,main])--EclipseLink, version: Eclipse Persistence Services - 2.5.0.v20130507-3faac2b
[EL Finest]: dbPlatformHelper_regExprDbPlatform: 2013-09-26 18:07:41.757--Thread(Thread[main,5,main])--(?i)oracle.*12 (There is no English translation for this message.)
[EL Finest]: dbPlatformHelper_regExprDbPlatform: 2013-09-26 18:07:41.757--Thread(Thread[main,5,main])--(?i)oracle.*11 (There is no English translation for this message.)
[EL Finest]: dbPlatformHelper_regExprDbPlatform: 2013-09-26 18:07:41.757--Thread(Thread[main,5,main])--(?i)oracle.*10 (There is no English translation for this message.)
[EL Finest]: dbPlatformHelper_regExprDbPlatform: 2013-09-26 18:07:41.758--Thread(Thread[main,5,main])--(?i)oracle.*9 (There is no English translation for this message.)
[EL Finest]: dbPlatformHelper_regExprDbPlatform: 2013-09-26 18:07:41.758--Thread(Thread[main,5,main])--(?i)oracle.* (There is no English translation for this message.)
[EL Finest]: dbPlatformHelper_regExprDbPlatform: 2013-09-26 18:07:41.758--Thread(Thread[main,5,main])--SQL\ Anywhere.* (There is no English translation for this message.)
[EL Finest]: dbPlatformHelper_regExprDbPlatform: 2013-09-26 18:07:41.758--Thread(Thread[main,5,main])--(?i)(sybase.*)|(adaptive\ server\ enterprise.*)|(SQL\ Server.*) (There is no English translation for this message.)
[EL Finest]: dbPlatformHelper_regExprDbPlatform: 2013-09-26 18:07:41.759--Thread(Thread[main,5,main])--(?i)microsoft.* (There is no English translation for this message.)
[EL Finest]: dbPlatformHelper_regExprDbPlatform: 2013-09-26 18:07:41.759--Thread(Thread[main,5,main])--(?i).*derby.* (There is no English translation for this message.)
[EL Finest]: dbPlatformHelper_regExprDbPlatform: 2013-09-26 18:07:41.759--Thread(Thread[main,5,main])--(?i).*db2.* (There is no English translation for this message.)
[EL Finest]: dbPlatformHelper_regExprDbPlatform: 2013-09-26 18:07:41.759--Thread(Thread[main,5,main])--(?i)pointbase.* (There is no English translation for this message.)
[EL Finest]: dbPlatformHelper_regExprDbPlatform: 2013-09-26 18:07:41.759--Thread(Thread[main,5,main])--(?i)mysql.* (There is no English translation for this message.)
[EL Fine]: connection: 2013-09-26 18:07:41.76--Thread(Thread[main,5,main])--Detected database platform: org.eclipse.persistence.platform.database.MySQLPlatform
[EL Config]: connection: 2013-09-26 18:07:41.771--ServerSession(8941730)--Connection(7521179)--Thread(Thread[main,5,main])--connecting(DatabaseLogin(
platform=>MySQLPlatform
user name=> "root"
datasource URL=> "jdbc:mysql://localhost:3306/sample"
))
[EL Config]: connection: 2013-09-26 18:07:41.783--ServerSession(8941730)--Connection(27722152)--Thread(Thread[main,5,main])--Connected: jdbc:mysql://localhost:3306/sample
User: root@localhost
Database: MySQL Version: 5.1.39-community
Driver: MySQL-AB JDBC Driver Version: mysql-connector-java-5.1.18 ( Revision: tonci.grgin@oracle.com-20110930151701-jfj14ddfq48ifkfq )
[EL Finest]: connection: 2013-09-26 18:07:41.783--ServerSession(8941730)--Connection(27722152)--Thread(Thread[main,5,main])--Connection acquired from connection pool [default].
[EL Finest]: connection: 2013-09-26 18:07:41.783--ServerSession(8941730)--Connection(27722152)--Thread(Thread[main,5,main])--Connection released to connection pool [default].
[EL Info]: connection: 2013-09-26 18:07:41.828--ServerSession(8941730)--Thread(Thread[main,5,main])--file:/C:/Users/achyut_anr/achyut_anr/CheckWeaving/bin/_TestDB login successful
[EL Finer]: metamodel: 2013-09-26 18:07:41.841--ServerSession(8941730)--Thread(Thread[main,5,main])--Canonical Metamodel class [com.altametrics.persistence.services.Person_] not found during initialization.
[EL Finer]: metamodel: 2013-09-26 18:07:41.842--ServerSession(8941730)--Thread(Thread[main,5,main])--Canonical Metamodel class [com.altametrics.persistence.services.Address_] not found during initialization.
[EL Finest]: jpa: 2013-09-26 18:07:41.842--ServerSession(8941730)--Thread(Thread[main,5,main])--End deploying Persistence Unit TestDB; session file:/C:/Users/achyut_anr/achyut_anr/CheckWeaving/bin/_TestDB; state Deployed; factoryCount 1
[EL Finer]: connection: 2013-09-26 18:07:41.863--ServerSession(8941730)--Thread(Thread[main,5,main])--client acquired: 3812334
[EL Finer]: transaction: 2013-09-26 18:07:41.872--ClientSession(3812334)--Thread(Thread[main,5,main])--acquire unit of work: 25692210
[EL Finest]: query: 2013-09-26 18:07:41.887--UnitOfWork(25692210)--Thread(Thread[main,5,main])--Execute query ReadObjectQuery(name="readAddress" referenceClass=Address sql="SELECT ID, ADDRESSLINE1, ADDRESSLINE2, personid FROM ADDRESS WHERE (ID = ?)")
[EL Finest]: connection: 2013-09-26 18:07:41.889--ServerSession(8941730)--Connection(27722152)--Thread(Thread[main,5,main])--Connection acquired from connection pool [default].
[EL Fine]: sql: 2013-09-26 18:07:41.889--ServerSession(8941730)--Connection(27722152)--Thread(Thread[main,5,main])--SELECT ID, ADDRESSLINE1, ADDRESSLINE2, personid FROM ADDRESS WHERE (ID = ?)
bind => [1]
[EL Finest]: connection: 2013-09-26 18:07:41.913--ServerSession(8941730)--Connection(27722152)--Thread(Thread[main,5,main])--Connection released to connection pool [default].
[EL Finest]: query: 2013-09-26 18:07:41.917--ServerSession(8941730)--Thread(Thread[main,5,main])--Execute query ReadObjectQuery(name="person" referenceClass=Person )
[EL Finest]: connection: 2013-09-26 18:07:41.917--ServerSession(8941730)--Connection(27722152)--Thread(Thread[main,5,main])--Connection acquired from connection pool [default].
[EL Fine]: sql: 2013-09-26 18:07:41.918--ServerSession(8941730)--Connection(27722152)--Thread(Thread[main,5,main])--SELECT ID, EMAIL, FIRSTNAME, LASTNAME FROM PERSON WHERE (ID = ?)
bind => [1]
[EL Finest]: connection: 2013-09-26 18:07:41.919--ServerSession(8941730)--Connection(27722152)--Thread(Thread[main,5,main])--Connection released to connection pool [default].
[EL Finest]: transaction: 2013-09-26 18:07:41.922--UnitOfWork(25692210)--Thread(Thread[main,5,main])--Register the existing object personId=1
我的持久化单元看起来像:
<persistence-unit name="TestDB">
<provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
<class>com.altametrics.persistence.services.Person</class>
<class>com.altametrics.persistence.services.Address</class>
<exclude-unlisted-classes>false</exclude-unlisted-classes>
<properties>
<property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/sample"/>
<property name="javax.persistence.jdbc.password" value="admin"/>
<property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver"/>
<property name="javax.persistence.jdbc.user" value="root"/>
<property name="eclipselink.weaving" value="static"/>
<!-- <property name="eclipselink.ddl-generation" value="drop-and-create-tables" /> -->
<property name="eclipselink.logging.level" value="FINEST"/>
</properties>
</persistence-unit>
最佳答案
一些惰性关系需要编织，并在 EclipseLink 中启用其他性能增强功能，例如获取组和更改跟踪，如 http://www.eclipse.org/eclipselink/documentation/2.4/concepts/app_dev007.htm 中所述。
编织通常在 EE 7 容器内自动发生，但需要在容器外或非 EE7 容器中进行。因此，为了懒惰地处理 1:1 和 M:1，您将需要通过使用代理来启用动态编织，或者静态编织类文件然后使用它们。
关于java - 延迟加载不适用于 eclipselink 中的 ManyToOne，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/18746259/