如何使用构造函数在选择子句中为多个表的选定列编写HQL JOIN查询(2)

查询1

final String GET_NOTIFICATIONS_FOR_USER =
"select new support.dto.Notify ( no.id,n.id,Integer.parseInt( n.notifier.user_id ),"
+ "concat ( n.notifier.employee.first_name,' ',n.notifier.employee.last_name ),"
+ "Integer.parseInt( nc.actor.user_id ),concat( nc.actor.employee.first_name,nc.actor.employee.last_name ),"
+ "no.entityId,no.entityTypeId,no.createdOn,n.isSeen,n.isViewed ) "
+ "from Notification n,NotificationObject no,NotificationChange nc,User u,Employee e "
+ "where n.notifier.user_id = :notifierId";

查询2

final String GET_NOTIFICATIONS_FOR_USER =
"select new support.dto.Notify ( no.id,n.notifier.employee.first_name ),n.isViewed ) "
+ "from NotificationChange nc inner join nc.notificationObject no "
+ "inner join no.notifications n "
+ "where n.notifier.user_id = :notifierId";

我正在接受以下异常

java.lang.NullPointerException
at org.hibernate.internal.util.ReflectHelper.getConstructor(ReflectHelper.java:309)
at org.hibernate.hql.internal.ast.tree.ConstructorNode.resolveConstructor(ConstructorNode.java:174)
at org.hibernate.hql.internal.ast.tree.ConstructorNode.prepare(ConstructorNode.java:144)
at org.hibernate.hql.internal.ast.HqlSqlWalker.processConstructor(HqlSqlWalker.java:1091)
at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectExpr(HqlSqlBaseWalker.java:2328)
at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectExprList(HqlSqlBaseWalker.java:2194)
at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectClause(HqlSqlBaseWalker.java:1476)
at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.query(HqlSqlBaseWalker.java:573)
at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectStatement(HqlSqlBaseWalker.java:301)
at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.statement(HqlSqlBaseWalker.java:249)
at org.hibernate.hql.internal.ast.QueryTranslatorImpl.analyze(QueryTranslatorImpl.java:262)
at org.hibernate.hql.internal.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:190)
at org.hibernate.hql.internal.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:142)
at org.hibernate.engine.query.spi.HQLQueryPlan.(HQLQueryPlan.java:115)
at org.hibernate.engine.query.spi.HQLQueryPlan.(HQLQueryPlan.java:76)
at org.hibernate.engine.query.spi.QueryPlanCache.getHQLQueryPlan(QueryPlanCache.java:150)
at org.hibernate.internal.AbstractSessionImpl.getHQLQueryPlan(AbstractSessionImpl.java:298)
at org.hibernate.internal.AbstractSessionImpl.createQuery(AbstractSessionImpl.java:236)
at org.hibernate.internal.SessionImpl.createQuery(SessionImpl.java:1821)
at support.DAO.MasterDaoImpl.getNotifications(MasterDaoImpl.java:115)
at support.service.MasterServiceImpl.getNotifications(MasterServiceImpl.java:158)
at support.service.MasterServiceImpl$$FastClassBySpringCGLIB$$a355463b.invoke()
at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:717)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157)
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:653)
at support.service.MasterServiceImpl$$EnhancerBySpringCGLIB$$8c2728e2.getNotifications()
at support.controller.WebSocketController.hello(WebSocketController.java:91)
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 org.springframework.messaging.handler.invocation.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:185)
at org.springframework.messaging.handler.invocation.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:104)
at org.springframework.messaging.handler.invocation.AbstractMethodMessageHandler.handleMatch(AbstractMethodMessageHandler.java:447)
at org.springframework.messaging.simp.annotation.support.SimpAnnotationMethodMessageHandler.handleMatch(SimpAnnotationMethodMessageHandler.java:443)
at org.springframework.messaging.simp.annotation.support.SimpAnnotationMethodMessageHandler.handleMatch(SimpAnnotationMethodMessageHandler.java:82)
at org.springframework.messaging.handler.invocation.AbstractMethodMessageHandler.handleMessageInternal(AbstractMethodMessageHandler.java:408)
at org.springframework.messaging.handler.invocation.AbstractMethodMessageHandler.handleMessage(AbstractMethodMessageHandler.java:346)
at org.springframework.messaging.support.ExecutorSubscribableChannel$SendTask.run(ExecutorSubscribableChannel.java:135)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
at java.lang.Thread.run(Thread.java:722)

解决方法

此外,您不能在HQL查询中添加Integer.parseInt.使用ResultSet中的预期类型,并从传入参数在构造函数内部执行转换.

（编辑：ASP站长网）