Spring JDBC Template- How to retrieve multiple result with multiple parameters with a single query

问题

I have a simple query which is

select distinct roleid,firstname,lastname where role_id='210';

I am using the same query for fetching the different lists such as projectnames ,projectmanagers name,developers...etc..based on the roleid that I am passing. My problem is I need to run the above query in a single shot by passing all the roleid and retrieve them in a single hit and assign those list to different list such as managers list ,developers list ,testers list ..etc and send it to the UI putting them in a linked hasmap.
Example

LinkedHashMap<String, List<SelectItem>> results = new LinkedHashMap<String, List<SelectItem>>();
    List<SelectItem> getProjectManager = getProjectManager(xxx);
    List<SelectItem> getResourceOwnerSE = getResourceOwner(yyy);
    List<SelectItem> getReqLeadPri = getReqLeadPri(zzz);
    results.put("getProjectManager", getProjectManager);
    results.put("getResourceOwner", getResourceOwnerSE);
    results.put("getReqLeadPri", getReqLeadPri);
    return results;

All the above methods getProjectManager(xxx),getResourceOwner(yyy),getReqLeadPri(zzz) runs with same query as mentioned above but passing different roleid xxx,yyy,zzz.

I don't know how to fetch a different list from a single query passing different parameters and assign to the list and return the results.

I am trying to achieve this because the UI is very slow when I try to get the lists individually from UI <-> DB each time when calling the same query passing different parameters each time for fetching different list. Hence, I am trying to get the results in a single shot.

回答1:

If you want to fir only one sql statement you can use ResultSetExtractor

public class SelectItemResultSetExtractor implements ResultSetExtractor<LinkedHashMap<String, List<SelectItem>>>{  

    public LinkedHashMap<String, List<SelectItem>> extractData(ResultSet rs) throws SQLException,  
            DataAccessException {  

        LinkedHashMap<String, List<SelectItem>> result = new ...
        //put the 3 categories with empty arraylists


        while(rs.next()){
            SelectItem item= new SelectItem();
            item.setRoleid(rs.getInt(1))  
            item.setFirstName(rs.getInt(2));  
            item.setLastName(rs.getString(3));

            //if item.getRoleid() is ProjManager
            // then put in the list of the ProjManager
            result.get("ProjManager").add(item);
            //if item.getRoleid() is ResourceOwnerSE
            // then put in the list of the ResourceOwnerSE
            ...
        }


        return result;  
    }  

}

来源：https://stackoverflow.com/questions/20950571/spring-jdbc-template-how-to-retrieve-multiple-result-with-multiple-parameters-w

标签

mysql

sql

Spring

jsf-2

spring-jdbc