我正在尝试使用Hibernate和HQL查询来获得行数。我写了以下代码：
public long countTexteEstALOrdreDuJour(String examenId) throws DAOException {
StringBuilder hqlQuery = new StringBuilder();
hqlQuery.append("SELECT count(*) ")
.append("FROM Examen as e ")
.append("JOIN e.organeSaisi as os ")
.append("JOIN os.texteDeLoi as t ")
.append("WHERE e.organeSaisi = some (SELECT ex.organeSaisi FROM Examen as ex WHERE ex.id = :examenId) ")
.append("AND e.examenEstALOrdreDuJour = 1 ");
try {
Query query = this.getSession().createQuery(hqlQuery.toString());
query.setParameter("examenId", examenId);
String result = (String)query.uniqueResult();
Long ret = null;
if (result==null) {
ret = 0l;
} else {
ret = Long.parseLong(result);
}
return ret;
} catch (JDBCException e) {
throw new DAOException(String.valueOf(e.getErrorCode()), e);
} catch (HibernateException e) {
throw new DAOException("HibernateException ", e);
}
}
调用该方法时，出现异常：
java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Long
at org.hibernate.type.descriptor.java.LongTypeDescriptor.unwrap(LongTypeDescriptor.java:36)
at org.hibernate.type.descriptor.sql.BigIntTypeDescriptor$1.doBind(BigIntTypeDescriptor.java:52)
at org.hibernate.type.descriptor.sql.BasicBinder.bind(BasicBinder.java:91)
at org.hibernate.type.AbstractStandardBasicType.nullSafeSet(AbstractStandardBasicType.java:283)
at org.hibernate.type.AbstractStandardBasicType.nullSafeSet(AbstractStandardBasicType.java:278)
at org.hibernate.param.NamedParameterSpecification.bind(NamedParameterSpecification.java:67)
at org.hibernate.loader.hql.QueryLoader.bindParameterValues(QueryLoader.java:578)
at org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1716)
at org.hibernate.loader.Loader.doQuery(Loader.java:801)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:274)
at org.hibernate.loader.Loader.doList(Loader.java:2542)
at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2276)
at org.hibernate.loader.Loader.list(Loader.java:2271)
at org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:459)
at org.hibernate.hql.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:365)
at org.hibernate.engine.query.HQLQueryPlan.performList(HQLQueryPlan.java:196)
at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1268)
at org.hibernate.impl.QueryImpl.list(QueryImpl.java:102)
at org.hibernate.impl.AbstractQueryImpl.uniqueResult(AbstractQueryImpl.java:890)
at com.an.eloi.model.dao.texte.TexteDAO.countTexteEstALOrdreDuJour(TexteDAO.java:247)
at com.an.eloi.model.domaine.texte.Texte.countTexteEstALOrdreDuJour(Texte.java:169)
at com.an.eloi.service.transactionnel.texte.TexteService.countTexteEstALOrdreDuJour(TexteService.java:348)
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:606)
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:317)
at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:183)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:96)
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:260)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:94)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:91)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
at com.sun.proxy.$Proxy39.countTexteEstALOrdreDuJour(Unknown Source)
at com.an.eloi.facade.texte.TexteFacade.countTexteEstALOrdreDuJour(TexteFacade.java:193)
at com.an.eloi.web.controller.texte.TexteController.updateTexte(TexteController.java:353)
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:606)
at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:215)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:743)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:672)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:82)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:919)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:851)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:953)
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:855)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:641)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:829)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at com.an.eloi.common.EloiActionFilter.doHttpFilter(EloiActionFilter.java:110)
at com.an.eloi.common.EloiActionFilter.doHttpFilterSynchronizedBySession(EloiActionFilter.java:158)
at com.an.eloi.common.EloiActionFilter.doFilter(EloiActionFilter.java:167)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at com.an.fwk.core.web.filter.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:84)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:225)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:169)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:999)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:565)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:307)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:745)
发生了什么事？
答案 0 :(得分：5)
在您的Examen实体中，id字段很可能是数字Long，因此应进行设置。设置查询参数值时，可以将examenId类型更改为Long或对其进行解析：
Query query = this.getSession().createQuery(hqlQuery.toString());
query.setParameter("examenId", Long.parseLong(examenId));
答案 1 :(得分：1)
一次获取“ count”作为数字会更好。像
Long result = (Long) query.uniqueResult();