我正在使用Jersey和Hibernate开发REST API。数据库为MySQL。我在设计中有几层，分别是dao layer，service layer和REST layer。请检查以下代码。
NotificationJSONService.java （REST层）
@GET
@Path("/getActiveNotifications")
@Produces (MediaType.APPLICATION_JSON)
public List<Notification> getActiveNotifications()
{
NotificationService service = new NotificationService();
List<Notification> notificationsByUser = service.getActiveNotifications();
return notificationsByUser;
}
NotificationService.java （服务层）
public List<Notification>getActiveNotifications()
{
Session session = getSession();
Transaction transaction = null;
List<Notification> list = new ArrayList<Notification>();
try
{
transaction = getTransaction(session);
list = notificationInterface.getActiveNotifications(session);
transaction.commit();
}
catch(Exception e)
{
e.printStackTrace();
}
finally
{
session.close();
for (int i = 0; i < list.size(); i++) {
User user = new User();
user.setIduser(list.get(i).getUser().getIduser());
list.get(i).setUser(user);
Product product = new Product();
product.setIdproduct(list.get(i).getProduct().getIdproduct());
list.get(i).setProduct(product);
NotificationType notificationType = new NotificationType();
notificationType.setIdnotificationType(list.get(i).getNotificationType().getIdnotificationType());
list.get(i).setNotificationType(notificationType);
}
}
return list;
}
NotificationDAOImpl.java （DAO层）
@Override
public List<Notification> getActiveNotifications(Session session)
{
Query query = session.createQuery("from notification where delete_timestamp IS NULL");
List list = query.list();
return list;
}
如您所见，以上所有代码均与名为notification的表相关。以下是notification bean信息。
Notification.java
public class Notification implements java.io.Serializable {
private Integer idnotification;
private NotificationType notificationType;
private Product product;
private User user;
private Date deleteTimestamp;
private Date dateCreated;
private Date lastUpdated;
public Notification() {
}
public Integer getIdnotification() {
return this.idnotification;
}
public void setIdnotification(Integer idnotification) {
this.idnotification = idnotification;
}
public NotificationType getNotificationType() {
return this.notificationType;
}
public void setNotificationType(NotificationType notificationType) {
this.notificationType = notificationType;
}
public Product getProduct() {
return this.product;
}
public void setProduct(Product product) {
this.product = product;
}
public User getUser() {
return this.user;
}
public void setUser(User user) {
this.user = user;
}
public Date getDeleteTimestamp() {
return this.deleteTimestamp;
}
public void setDeleteTimestamp(Date deleteTimestamp) {
this.deleteTimestamp = deleteTimestamp;
}
public Date getDateCreated() {
return this.dateCreated;
}
public void setDateCreated(Date dateCreated) {
this.dateCreated = dateCreated;
}
public Date getLastUpdated() {
return this.lastUpdated;
}
public void setLastUpdated(Date lastUpdated) {
this.lastUpdated = lastUpdated;
}
}
Notification.hbm.xml
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<!-- Generated Jan 31, 2019, 6:16:44 PM by Hibernate Tools 4.3.1 -->
<hibernate-mapping>
<class name="xxx.xxx.api.beans.Notification" table="notification" catalog="xxx" optimistic-lock="version">
<id name="idnotification" type="java.lang.Integer">
<column name="idnotification" />
<generator class="identity" />
</id>
<many-to-one name="notificationType" class="xxx.xxx.api.beans.NotificationType" fetch="select">
<column name="notification_type_idnotification_type" not-null="true" />
</many-to-one>
<many-to-one name="product" class="xxx.xxx.api.beans.Product" fetch="select">
<column name="product_idproduct" not-null="true" />
</many-to-one>
<many-to-one name="user" class="xxx.xxx.api.beans.User" fetch="select">
<column name="user_iduser" not-null="true" />
</many-to-one>
<property name="deleteTimestamp" type="timestamp">
<column name="delete_timestamp" length="19" />
</property>
<property name="dateCreated" type="timestamp">
<column name="date_created" length="19" />
</property>
<property name="lastUpdated" type="timestamp">
<column name="last_updated" length="19" not-null="true" />
</property>
</class>
</hibernate-mapping>
下面是notification SQL表
CREATE TABLE IF NOT EXISTS `notification` (
`idnotification` INT NOT NULL AUTO_INCREMENT,
`user_iduser` INT NOT NULL,
`product_idproduct` INT NOT NULL,
`notification_type_idnotification_type` INT NOT NULL,
`delete_timestamp` TIMESTAMP NULL,
`date_created` TIMESTAMP NULL,
`last_updated` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
PRIMARY KEY (`idnotification`),
INDEX `fk_notification_user1_idx` (`user_iduser` ASC),
INDEX `fk_notification_product1_idx` (`product_idproduct` ASC),
INDEX `fk_notification_notification_type1_idx` (`notification_type_idnotification_type` ASC),
CONSTRAINT `fk_notification_user1`
FOREIGN KEY (`user_iduser`)
REFERENCES `user` (`iduser`)
ON DELETE NO ACTION
ON UPDATE NO ACTION,
CONSTRAINT `fk_notification_product1`
FOREIGN KEY (`product_idproduct`)
REFERENCES `product` (`idproduct`)
ON DELETE NO ACTION
ON UPDATE NO ACTION,
CONSTRAINT `fk_notification_notification_type1`
FOREIGN KEY (`notification_type_idnotification_type`)
REFERENCES `notification_type` (`idnotification_type`)
ON DELETE NO ACTION
ON UPDATE NO ACTION)
通过以下URL（http://localhost:8080/XXX/rest/notification/getActiveNotifications）运行getActiveNotifications方法时，出现以下错误。
org.hibernate.hql.internal.ast.QuerySyntaxException: notification is not mapped [from notification where delete_timestamp IS NULL]
at org.hibernate.hql.internal.ast.QuerySyntaxException.generateQueryException(QuerySyntaxException.java:96)
at org.hibernate.QueryException.wrapWithQueryString(QueryException.java:120)
at org.hibernate.hql.internal.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:234)
at org.hibernate.hql.internal.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:158)
at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:126)
at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:88)
at org.hibernate.engine.query.spi.QueryPlanCache.getHQLQueryPlan(QueryPlanCache.java:190)
at org.hibernate.internal.AbstractSessionImpl.getHQLQueryPlan(AbstractSessionImpl.java:301)
at org.hibernate.internal.AbstractSessionImpl.createQuery(AbstractSessionImpl.java:236)
at org.hibernate.internal.SessionImpl.createQuery(SessionImpl.java:1796)
at xxx.xxx.api.dao.notification.NotificationDAOImpl.getActiveNotifications(NotificationDAOImpl.java:101)
at xxx.xxx.api.service.NotificationService.getActiveNotifications(NotificationService.java:299)
at xxx.xxx.api.rest.NotificationJSONService.getActiveNotifications(NotificationJSONService.java:114)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:566)
at org.glassfish.jersey.server.model.internal.ResourceMethodInvocationHandlerFactory.lambda$static$0(ResourceMethodInvocationHandlerFactory.java:76)
at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher$1.run(AbstractJavaResourceMethodDispatcher.java:148)
at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.invoke(AbstractJavaResourceMethodDispatcher.java:191)
at org.glassfish.jersey.server.model.internal.JavaResourceMethodDispatcherProvider$TypeOutInvoker.doDispatch(JavaResourceMethodDispatcherProvider.java:243)
at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.dispatch(AbstractJavaResourceMethodDispatcher.java:103)
at org.glassfish.jersey.server.model.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:493)
at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:415)
at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:104)
at org.glassfish.jersey.server.ServerRuntime$1.run(ServerRuntime.java:277)
at org.glassfish.jersey.internal.Errors$1.call(Errors.java:272)
at org.glassfish.jersey.internal.Errors$1.call(Errors.java:268)
at org.glassfish.jersey.internal.Errors.process(Errors.java:316)
at org.glassfish.jersey.internal.Errors.process(Errors.java:298)
at org.glassfish.jersey.internal.Errors.process(Errors.java:268)
at org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:289)
at org.glassfish.jersey.server.ServerRuntime.process(ServerRuntime.java:256)
at org.glassfish.jersey.server.ApplicationHandler.handle(ApplicationHandler.java:703)
at org.glassfish.jersey.servlet.WebComponent.serviceImpl(WebComponent.java:416)
at org.glassfish.jersey.servlet.WebComponent.service(WebComponent.java:370)
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:389)
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:342)
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:229)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:490)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:668)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408)
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:834)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1417)
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: org.hibernate.hql.internal.ast.QuerySyntaxException: notification is not mapped
at org.hibernate.hql.internal.ast.util.SessionFactoryHelper.requireClassPersister(SessionFactoryHelper.java:189)
at org.hibernate.hql.internal.ast.tree.FromElementFactory.addFromElement(FromElementFactory.java:109)
at org.hibernate.hql.internal.ast.tree.FromClause.addFromElement(FromClause.java:95)
at org.hibernate.hql.internal.ast.HqlSqlWalker.createFromElement(HqlSqlWalker.java:331)
at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.fromElement(HqlSqlBaseWalker.java:3633)
at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.fromElementList(HqlSqlBaseWalker.java:3522)
at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.fromClause(HqlSqlBaseWalker.java:706)
at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.query(HqlSqlBaseWalker.java:562)
at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectStatement(HqlSqlBaseWalker.java:299)
at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.statement(HqlSqlBaseWalker.java:247)
at org.hibernate.hql.internal.ast.QueryTranslatorImpl.analyze(QueryTranslatorImpl.java:278)
at org.hibernate.hql.internal.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:206)
... 58 more
这是什么问题？另外请注意，在MySQL查询中，我同时使用了delete_timestamp和deleteTimestamp，但都遇到了相同的错误。
答案 0 :(得分：2)
在Hibernate（和JPA）中，映射是到类，即Notification的。 HQL使用您的实体类工作，并且区分大小写。
考虑到这一点，您的HQL查询
from notification where delete_timestamp IS NULL
应该是
from Notification where deleteTimestamp IS NULL
^ ^
|---> class |---> attribute in your class