Problemas com a geração de Relatórios no iReport

import java.util.HashMap;

import javax.swing.JOptionPane;

import net.sf.jasperreports.engine.JRException;

import net.sf.jasperreports.engine.JRResultSetDataSource;

import net.sf.jasperreports.engine.JasperCompileManager;

import net.sf.jasperreports.engine.JasperFillManager;

import net.sf.jasperreports.engine.JasperManager;

import net.sf.jasperreports.engine.JasperPrint;

import net.sf.jasperreports.view.JasperViewer;

import utilitarios.conexao;

conexao con = new conexao();

public relatorio_produto(){

    try {
        con.conecta();
        con.executaSQL("select * from produtos");
        JRResultSetDataSource jrRS = new JRResultSetDataSource(con.resultset);
        JasperPrint jasperPrint = JasperFillManager.fillReport("relatorios/relatorio_produto.jasper", new HashMap(), jrRS);
        JasperViewer.viewReport(jasperPrint);

    } catch (Exception erro) {
        JOptionPane.showMessageDialog(null, "Deu o erro:" + erro);
    }

}

public static void main(String args[]){

    new relatorio_produto();
}

import java.io.IOException;
import java.io.StringReader;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.HashMap;
import javax.swing.text.BadLocationException;
import javax.swing.text.rtf.RTFEditorKit;



import net.sf.jasperreports.engine.JRException;
import net.sf.jasperreports.engine.JRResultSetDataSource;
import net.sf.jasperreports.engine.JasperCompileManager;
import net.sf.jasperreports.engine.JasperFillManager;
import net.sf.jasperreports.engine.JasperManager;
import net.sf.jasperreports.engine.JasperPrint;
import net.sf.jasperreports.view.JasperViewer;
import net.sf.jasperreports.engine.JasperPrintManager;


public class abrerelatorio {

public static java.sql.Connection conex;
public String titulos[] = new String[10];

public opencarrego(java.sql.Connection cong, String titulog[], String pedg) { 

	  	conex = cong;
	  	titulos = titulog;	

		String fantasiaw = titulos[0];
		String docw = pedg;



        try {


		   	String rootDir = "pasta_relatorios/";  

   			java.util.Map parameters = new HashMap();
   			parameters.put("Emp", ""+fantasiaw+""); 
   			parameters.put("dados", ""+docw+""); 

//----------------- se for utilizar sub relatorios ----------------------------------
/*   			String subreportFile1 = rootDir+"subrel1.jasper";
   			String subreportFile2 = rootDir+"subrel2.jasper";

   			parameters.put("SUBREPORT_DIR1", ""+subreportFile1.toString()+""  ) ; 
   			parameters.put("SUBREPORT_DIR2", ""+subreportFile2.toString()+""  ) ; 
   			parameters.put("REPORT_CONNECTION", conex ) ;       */
//------------------------------ sub relatorios ---------------------------------------

   			String reportFilename = rootDir+"nomedorelatorio.jasper";
        

			JasperPrint jasperPrint = JasperFillManager.fillReport(reportFilename, parameters, conex); 
 			JasperViewer.viewReport(jasperPrint, false); 


	    } catch (Exception e) {
         		System.out.println("Ocorreu um erro: " + e.toString() );
         		e.printStackTrace();
      	}

     }    

}


---------------- com consulta sql ---------------- troca este trecho ----------------
Statement statement = conex.createStatement();
rs = statement.executeQuery(selectw);  //"Select  * from esprodutos"
JRResultSetDataSource jrRS = new JRResultSetDataSource(rs);
JasperPrint jasperPrint = JasperFillManager.fillReport(relatw, parameters, jrRS);  
JasperViewer.viewReport(jasperPrint, false);