java - 无法在延迟加载数据表中使用数字筛选器 : ClassCastException String to Integer

Question

这是我的代码:

xhtml:

            <p:dataTable id="dataTable" var="variable" value="#{myBean.lazyList}" 
                widgetVar="widgetVar"
                emptyMessage="Empty."
                filteredValue="#{myBean.filteredLazyList}"
                paginator="true" rows="100" 
                paginatorTemplate="{RowsPerPageDropdown} {FirstPageLink} {PreviousPageLink} {CurrentPageReport} {NextPageLink} {LastPageLink}"  
                rowsPerPageTemplate="100,150,200" lazy="true" rendered="true"
                selectionMode="single" selection="#{myBean.selectedRow}" > 

                <p:column id="yearColumn" filterBy="#{variable.year}" sortBy="#{variable.year}" headerText="Ano" filterMatchMode="contains" >
                    <h:outputText value="#{variable.year}" />
                </p:column>

从我的 LazyDataModel 实现加载方法:

@Override
public List<Thing> load(int startingAt, int maxPerPage, String sortField, SortOrder sortOrder, Map<String, String> filters) {

    MyDAO dao = new MyDAO();

    try {
        myList = dao.findMyThings(startingAt, maxPerPage, sortField, sortOrder, filters);
    } catch (Exception e) {
        e.printStackTrace();
    }

    if(getRowCount() <= 0){
        setRowCount(dao.countMyThingsNoPagination(filters));
    }

    if(maxPerPage > 0){ 
        setPageSize(maxPerPage);
    }

    return myList;
}

我的 DAO 类中的搜索方法:

public List<Thing> findMyThings(int startingAt, int maxPerPage,
        String sortField, SortOrder sortOrder, Map<String, String> filters) {

    session = HibernateUtil.getSession();
    Criteria criteria =session.createCriteria(Thing.class); 

    if(maxPerPage > 0){
        criteria.setMaxResults(maxPerPage);
    }

    criteria.setFirstResult(startingAt);

    for(Map.Entry<String, String> entry : filters.entrySet()){
        if(!Util.isEmpty(entry.getValue())){
            if(entry.getKey().contains(".")){
                String first = (entry.getKey().split("\\."))[0];
                criteria.createAlias(first, first);
            }
            criteria.add(Restrictions.and(Restrictions.eq(entry.getKey(), entry.getValue())));
        }
    }

    if(sortField != null && !sortField.isEmpty()){

        if(sortOrder.equals(SortOrder.ASCENDING)){
            criteria.addOrder(Order.asc(sortField) );
        }
        else if(sortOrder.equals(SortOrder.DESCENDING)){
            criteria.addOrder(Order.desc(sortField) );
        }
    }
    else{
        criteria.addOrder(Order.desc("insertDate") );
    }

    @SuppressWarnings("unchecked")
    List<Thing> things = (List<Thing>) criteria.list();

    session.close();
    return things;
}

一切工作正常，除非我尝试使用“年份”列过滤器。如果它是一个字符串，它会工作，但是，“year”是一个 int 类型，并且我收到以下错误:

java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Integer
    at org.hibernate.type.descriptor.java.IntegerTypeDescriptor.unwrap(IntegerTypeDescriptor.java:36)
    at org.hibernate.type.descriptor.sql.IntegerTypeDescriptor$1.doBind(IntegerTypeDescriptor.java:57)
    at org.hibernate.type.descriptor.sql.BasicBinder.bind(BasicBinder.java:93)
    at org.hibernate.type.AbstractStandardBasicType.nullSafeSet(AbstractStandardBasicType.java:280)
    at org.hibernate.type.AbstractStandardBasicType.nullSafeSet(AbstractStandardBasicType.java:275)
    at org.hibernate.loader.Loader.bindPositionalParameters(Loader.java:1968)
    at org.hibernate.loader.Loader.bindParameterValues(Loader.java:1939)
    at org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1874)
    at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1835)
    at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1815)
    at org.hibernate.loader.Loader.doQuery(Loader.java:899)
    at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:341)
    at org.hibernate.loader.Loader.doList(Loader.java:2522)
    at org.hibernate.loader.Loader.doList(Loader.java:2508)
    at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2338)
    at org.hibernate.loader.Loader.list(Loader.java:2333)
    at org.hibernate.loader.criteria.CriteriaLoader.list(CriteriaLoader.java:124)
    at org.hibernate.internal.SessionImpl.list(SessionImpl.java:1662)
    at org.hibernate.internal.CriteriaImpl.list(CriteriaImpl.java:374)
    at dao.ThingDAO.findThings(ThingDAO.java:99)
    at lazyDataModel.LazyThingDataModel.load(LazyThingDataModel.java:25)
    at org.primefaces.component.datatable.DataTable.loadLazyData(DataTable.java:737)
    at org.primefaces.component.datatable.feature.FilterFeature.encode(FilterFeature.java:85)
    at org.primefaces.component.datatable.DataTableRenderer.encodeEnd(DataTableRenderer.java:76)
    at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:879)
    at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1650)
    at com.sun.faces.context.PartialViewContextImpl$PhaseAwareVisitCallback.visit(PartialViewContextImpl.java:479)
    at com.sun.faces.component.visit.PartialVisitContext.invokeVisitCallback(PartialVisitContext.java:175)
    at org.primefaces.component.api.UIData.visitTree(UIData.java:675)
    at javax.faces.component.UIComponent.visitTree(UIComponent.java:1487)
    at javax.faces.component.UIComponent.visitTree(UIComponent.java:1487)
    at javax.faces.component.UIForm.visitTree(UIForm.java:331)
    at javax.faces.component.UIComponent.visitTree(UIComponent.java:1487)
    at javax.faces.component.UIComponent.visitTree(UIComponent.java:1487)
    at com.sun.faces.context.PartialViewContextImpl.processComponents(PartialViewContextImpl.java:361)
    at com.sun.faces.context.PartialViewContextImpl.processPartial(PartialViewContextImpl.java:282)
    at org.primefaces.context.PrimePartialViewContext.processPartial(PrimePartialViewContext.java:57)
    at javax.faces.component.UIViewRoot.encodeChildren(UIViewRoot.java:968)
    at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1643)
    at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:378)
    at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:127)
    at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:117)
    at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:97)
    at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:135)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:309)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.primefaces.webapp.filter.FileUploadFilter.doFilter(FileUploadFilter.java:98)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51)
    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:222)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1041)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:603)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
    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)

我想也许可以使用过滤器转换器，但我不知道如何将转换器设置为 p:column 过滤器...

我应该做什么？

谢谢!!

Answer 1

异常跟踪分析表明，以下行导致了问题

List<Thing> things = (List<Thing>) criteria.list();

当您收到 ClassCastException 时，意味着 criteria.list() 返回的结果无法正确转换为 List。正如你所说，它适用于 String 文件，但不适用于 int，我可以在 Thing 类的 Hibernate 映射文件中看到问题。

当您将 year datatye 更改为 int 时，您需要在 DB 和 Hibernate 映射文件中进行相同的更改。由于缺少此内容，数据库结果即 Varchar 类型(String)无法转换为 int。因此引发了 ClassCastException。

因此，我的建议是更改数据库和 Hibernate 映射文件中的数据类型。这应该可以解决您的问题。