java - 调用 Query.uniqueResult() 时出现 ClassCastException

Question

我正在尝试使用 Hibernate 和 HQL 查询来获取行数。我写了下面的代码:

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);
    }
}

当我调用该方法时，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？

Answer 1

很可能在您的 Examen 实体中，id 字段是一个数字 Long 并且应该这样设置。将 examenId 类型更改为 Long 或在设置查询参数值时解析它:

Query query = this.getSession().createQuery(hqlQuery.toString());
query.setParameter("examenId", Long.parseLong(examenId));