Question

i am writing an application in which i am creating web services. i am creating an operation(method) which retrieves database table values from database table in resultset. Hence we can’t return resultset value directly in web services. i am creating a class which holds the values from resultset. instead of resultset i am returning object[] of newly created class as follows :

 public HistoryInfoByUser[] get_HistoryInfoByUser(@WebParam(name = "email_Id")
  String email_Id) throws Exception{

        HistoryInfoByUser[] historyIn = null;
        if (conn != null) {
        CallableStatement cst = conn.prepareCall("{call sp_xxxx(?)}",ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_READ_ONLY);
            cst.setString(1, email_Id);
            ResultSet resultSet = cst.executeQuery();
             int rowCount = resultSet.getRow();

           historyIn = new HistoryInfoByUser[rowCount];

          while (resultSet.next())
             {

                historyIn[rowCounter].setId(rowCounter);                               
           historyIn[rowCounter].setStartTime((java.util.Date)resultSet.getObject(1));
                historyIn[rowCounter].setType((String) resultSet.getObject(2));


             rowCounter++;
            }
        }
        return historyIn;
    }

but while trying to access those values in web service client, it is giving java.lang.NullPointerException.

here is the code that i am using in web service client for accessing resultset
values :

    public void get_HistoryInfoByUser(String email_Id) 
{      
               service = new DBService();

               port = service.getDBPort();

    try {

        List<HistoryInfoByUser> historyIn = port.getHistoryInfoByUser(email_Id);
      Iterator iterator = historyIn.iterator();
            while (iterator.hasNext()){
              System.out.print(iterator.next()+" ");  
            }
      } catch (Exception_Exception ex) {
        Logger.getLogger(DataBaseWSHelper.class.getName()).log(Level.SEVERE, null, ex);
    }

 }

I tried returning a singe row value by returning an object (HistoryInfoByUser) of newly created class instead of object[] (HistoryInfoByUser[] ). It works fine with single object but giving NullPointerException when i am using object[]. i am not getting any way which will help me to overcome with this problem of accessing resultset value.

I thank in advance to your all valuable suggestions which will help me to overcome with this problem.

Answer 1

Return a WebRowSet from your web service:

import javax.sql.rowset.WebRowSet;
import com.sun.rowset.WebRowSetImpl; // Reference implementation
...
// get ResultSet rs from db
WebRowSet wrs = new WebRowSetImpl();
wrs.populate(rs);
// return wrs from web service

Note that your JDBC provider might provide a vendor-specific WebRowSet implementation. You can use that instead of the reference implementation.