为什么我得到以下异常

Question

this is my nodefinder.java file

package com.acme.web.action.executer;

import java.sql.ResultSet;
import java.util.Map;

import org.alfresco.web.bean.repository.Node;
import org.alfresco.web.bean.repository.Repository;
import org.alfresco.web.ui.common.component.UIActionLink;

import javax.faces.context.FacesContext;
import javax.faces.event.ActionEvent;

import org.alfresco.service.cmr.model.FileFolderService;
import org.alfresco.service.cmr.repository.NodeRef;
import org.alfresco.service.cmr.repository.NodeService;
import org.alfresco.service.cmr.repository.StoreRef;
import org.alfresco.service.cmr.search.SearchParameters;
import org.alfresco.service.cmr.search.SearchService;

public class NodeFinder {

    // private static final String = null;
    SearchParameters sp = new SearchParameters();
    private NodeService nodeService;
    private FileFolderService fileFolderService;
    //geting the filefolder service                     
    public FileFolderService getFileFolderService() {
        return fileFolderService;
    }
    // setting the file folder service 
    public void setFileFolderService(FileFolderService fileFolderService) {
        this.fileFolderService = fileFolderService;
    }
// getting the node servise 
    public NodeService getNodeService() {
        return nodeService;
    }
    // setting the node server 

    public void setNodeService(NodeService nodeService) {
        this.nodeService = nodeService;
    }

    public void execute(ActionEvent event) {
        ResultSet resultSet_s = null;
        UIActionLink comp = (UIActionLink) event.getComponent();
        Map<String, String> params = comp.getParameterMap();
        String id = params.get("id1");
        System.out.println("1");

        NodeRef actionedUponNodeRef = new NodeRef(Repository.getStoreRef(), id);
        String qry_s = "@cm\\:name:train";
        System.out.println("2");

        SearchParameters sp_s = new SearchParameters();
        System.out.println("3");

        sp_s.addStore(StoreRef.STORE_REF_WORKSPACE_SPACESSTORE);
        sp_s.setLanguage(SearchService.LANGUAGE_LUCENE);

        sp_s.setQuery(qry_s);
        System.out.println( "4" );

        Node node = new Node(actionedUponNodeRef);
        System.out.println("5");
        resultSet_s = (ResultSet) Repository.getServiceRegistry(
                FacesContext.getCurrentInstance()).getSearchService().query(
                sp_s);
        System.out.println("5.1");

        if (resultSet_s != null) {
            System.out.println("6");

            System.out.println("Node value is::::" + node.getName());

        }
    }
}

Answer 1

Because you imported java.sql.ResultSet instead of an alfresco class/interface compatible to org.alfresco.repo.search.impl.lucene.PagingLuceneResultSet

Answer 2

Look at that line ...(ResultSet) Repository.getServiceRegistry(... , then look at your exception and finally at your imports. There you will see that ResultSet is actually java.sql.ResultSet (which is indicated by your ClassCastException's message).

If you then look at the super classes or interfaces of org.alfresco.repo.search.impl.lucene.PagingLuceneResultSet I'd say you won't find any java.sql.ResultSet . That's why you get that exception.