我想用JTA进行多线程处理。
环境：
治疗：我想生成一个包含数据库中所有数据的zip。这个zip文件可能很大，所以我想在jboss将它发送给客户端的同时启动一个线程来生成流。
我的REST条目：
@Stateless
@Path("/exportProcess")
public class ExportProcessusResource {
@Inject
private IExport export;
@GET
@Path("/{processCode: [^/]+}")
@Produces(MediaType.APPLICATION_OCTET_STREAM)
public Response export(@PathParam("processCode") final String pProcessCode) {
return Response.ok(export.export(pProcessCode))
.header("Content-Disposition", "attachment; filename=" + pCodeProcessus + ".zip")
.build();
}
}
我的模特：
@Entity
@Table(name = "T_PROCESS")
@NamedQueries({
@NamedQuery(name = "Process.GetByCode", query = "SELECT p FROM Process p WHERE p.code=:code")
})
public class Process {
@Column(name = "CODE", length = 50, nullable = false)
private String code;
@OneToMany(mappedBy = "process", targetEntity = Step.class)
private Collection<Step> steps;
//Getters/Setters
}
@Entity
@Table(name = "T_STEP")
public class STEP {
@Id
@Column(name = "ID_STEP")
@GeneratedValue(strategy = GenerationType.AUTO, generator = "SEQ_ID_STEP")
@SequenceGenerator(name = "SEQ_ID_STEP", sequenceName = "SEQ_ID_STEP")
private int id;
@ManyToOne(targetEntity = Process.class)
@JoinColumn(name = "CODE_PROCESS", referencedColumnName = "CODE", nullable = false)
private Process process;
//Getters/Setters
}
我的道：
public interface IProcessDao {
Processus getByCode(final String pCode);
}
public class ProcessDao implements IProcessDao {
@Override
public Processus getByCode(final String pCode) {
Processus lResult = null;
try {
final TypedQuery<Processus> lRequest = pEm.createNamedQuery("Process.GetByCode", Process.class);
lRequest.setParameter("code", pCode);
lResult = lRequest.getSingleResult();
} catch (final NoResultException e) {
// Return null
lResult = null;
}
return lResult;
}
}
我的控制器：
public interface IExport {
/**
* Generate export
*
* @param pProcessCode Process code
* @return Datas
*/
InputStream export(final String pProcessCode);
}
public class Export implements IExport {
@PersistenceContext(unitName="authorizations")
private EntityManager entityManagerAuthorizations;
@Inject
private ExportThreadHelper exportThreadHelper;
@Override
public InputStream export(final String pProcessCode) {
//Check if user has the profile. Use database "AUTHORIZATIONS"
checkProfil(entityManagerAuthorizations, Profiles.ADMIN);
final PipedInputStream lInputStream = new PipedInputStream();
OutputStream lOutputStream = null;
try {
lOutputStream = new FileOutputStream("d:/test.zip");// new
// PipedOutputStream(lInputStream);
} catch (final IOException e) {
throw new RuntimeException("Cannot start zip generation", e);
}
final ZipOutputStream lZipOutputStream = new ZipOutputStream(lOutputStream);
final Runnable lRunnable = new Runnable() {
@Override
public void run() {
try {
exportThreadHelper.export(pProcessCode, lZipOutputStream);
} catch (final Exception e) {
logger.error(e);
} finally {
IOUtils.closeQuietly(lZipOutputStream);
}
}
};
//To execute in same thread :
//lRunnable.run();
//To execute in another thread
final Thread lThread = new Thread(lRunnable);
lThread.start();
try {
lThread.join();
} catch (final InterruptedException e1) {
throw new RuntimeException(e1);
}
try {
return new FileInputStream("d:/test.zip");
} catch (final FileNotFoundException e) {
logger.error(e);
}
return lInputStream;
}
}
public class ExportThreadHelper {
private class ProcessToExport {
//...
}
@PersistenceContext
@Named("Application")
private EntityManager entityManagerThreadable;
@Inject
private IProcessDao processDao;
public void export(final String pProcesssCode, final ZipOutputStream pZipOutputStream)
throws MyWayBusinessException {
try {
final ProcessToExport lProcessToExport = new ProcessToExport();
transaction(entityManagerThreadable, new Callable<Void>() {
@Override
public Void execute() {
final Process lProcess = processDao.getByCode(pProcesssCode);
for (final Step lStep : lProcess.getSteps()) {
//Many things
}
return null;
}
});
//MANY OTHER TREATMENTS
} catch (final Exception e) {
logger.error(e);
throw new RuntimeException("Cannot generate export", e);
}
}
@Override
@TransactionAttribute(TransactionAttributeType.REQUIRED)
protected <T> T transaction(final EntityManager pEntityManager, final Callable<T> pCallable) {
//I've tried with and without the annotation and with and without the "UserTransaction"
try {
final UserTransaction tx = com.arjuna.ats.jta.UserTransaction.userTransaction();
try {
tx.begin();
final T lResultat = pCallable.execute();
tx.commit();
return lResultat;
} catch (final Throwable e) {
tx.rollback();
throw e;
}
} catch (final Throwable e) {
throw new RuntimeException(e);
}
}
}
我的persistence.xml：
<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0"
xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd ">
<persistence-unit name="APPLICATION" transaction-type="JTA">
<jta-data-source>java:/jdbc/app</jta-data-source>
<class>Processus</class>
<class>Step</class>
<properties>
<!-- Scan for annotated classes and Hibernate mapping XML files -->
<property name="hibernate.archive.autodetection" value="class, hbm" />
</properties>
</persistence-unit>
<persistence-unit name="AUTHORIZATION" transaction-type="JTA">
<jta-data-source>java:/jdbc/AUTHORIZATION</jta-data-source>
<!-- many things... -->
</persistence-unit>
</persistence>
（我已经清理了代码以保留重要的东西）。
并且，如果我使用monothread版本（lRunnable.run（））我是zip文件，但如果我运行多线程版本（thread.start（））（我已经阻止了这里为了确保我的测试连接不被父线程关闭，但在我将删除thread.join（）之后我发现了这个例外：
ERROR [... ExportThreadHelper]（Thread-115）无法初始化懒惰 角色集合：.steps，无法初始化代理 - 没有会话： org.hibernate.LazyInitializationException：懒得初始化 角色集合：.steps，无法初始化代理 - 没有会话 在 org.hibernate.collection.internal.AbstractPersistentCollection.throwLazyInitializationException（AbstractPersistentCollection.java:569） [hibernate-core-4.2.14.SP1-redhat-1.jar：4.2.14.SP1-redhat-1] at org.hibernate.collection.internal.AbstractPersistentCollection.withTemporarySessionIfNeeded（AbstractPersistentCollection.java:188） [hibernate-core-4.2.14.SP1-redhat-1.jar：4.2.14.SP1-redhat-1] at org.hibernate.collection.internal.AbstractPersistentCollection.initialize（AbstractPersistentCollection.java:548） [hibernate-core-4.2.14.SP1-redhat-1.jar：4.2.14.SP1-redhat-1] at org.hibernate.collection.internal.AbstractPersistentCollection.read（AbstractPersistentCollection.java:126） [hibernate-core-4.2.14.SP1-redhat-1.jar：4.2.14.SP1-redhat-1] at org.hibernate.collection.internal.PersistentBag.iterator（PersistentBag.java:266） [hibernate-core-4.2.14.SP1-redhat-1.jar：4.2.14.SP1-redhat-1] at ExportThreadHelper $ 1.execute（ExportThreadHelper.java:101） [metier-2.3.0-SNAPSHOT.jar：] at ExportThreadHelper $ 1.execute（ExportThreadHelper.java:1） [metier-2.3.0-SNAPSHOT.jar：] at ExportThreadHelper.transaction（ExportThreadHelper.java:148） [metier-2.3.0-SNAPSHOT.jar：] at ExportThreadHelper.export（ExportThreadHelper.java:97） [metier-2.3.0-SNAPSHOT.jar：] at ExportMetier $ 1.run（ExportMetier.java:62）[metier-2.3.0-SNAPSHOT.jar：] 在java.lang.Thread.run（Thread.java:722）[rt.jar：1.7.0_04]
您是否在我的代码中看到了问题？
答案 0 :(得分：0)
您需要像这样更改查询：
@NamedQueries({
@NamedQuery(name = "Process.GetByCode", query = "SELECT p FROM Process p LEFT JOIN FETCH p.steps WHERE p.code=:code")
})