Gerar arquivo excel ireport

import java.sql.Connection;import java.sql.DriverManager;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;import java.util.HashMap;import java.util.Map;   
import net.sf.jasperreports.engine.JRException;   
import net.sf.jasperreports.engine.JRResultSetDataSource;   
import net.sf.jasperreports.engine.JasperCompileManager;   
import net.sf.jasperreports.engine.JasperExportManager;   
import net.sf.jasperreports.engine.JasperFillManager;   
import net.sf.jasperreports.engine.JasperPrint;   
import net.sf.jasperreports.engine.JasperReport;   
import net.sf.jasperreports.engine.design.JasperDesign;   
import net.sf.jasperreports.engine.xml.JRXmlLoader;   
import net.sf.jasperreports.view.JasperViewer;   
  
public class relat_calculos {   
  
    private static final String url = "org.postgresql.Driver";   
    private static final String driver = "jdbc:postgresql://localhost/saidas";   
    private static final String login = "postgres";   
    private static final String pwd = "4545";   
     
    public relat_calculos() {   
    }   
     
    public void gerar( String layout ) throws JRException , SQLException, ClassNotFoundException {   
        //gerando o jasper design   
        JasperDesign desenho = JRXmlLoader.load( layout );   
     
        //compila o relatório   
        JasperReport relatorio = JasperCompileManager.compileReport( desenho );   
     
        //estabelece conexão   
        Class.forName( driver );   
        Connection con = DriverManager.getConnection( url , login , pwd );   
        Statement stm = con.createStatement();   
        String query = "select * from calculos";   
        ResultSet rs = stm.executeQuery( query );   
  
        //implementação da interface JRDataSource para DataSource ResultSet   
        JRResultSetDataSource jrRS = new JRResultSetDataSource( rs );   
     
        //executa o relatório   
        Map parametros = new HashMap();   
        parametros.put("nota", new Double(10));   
        JasperPrint impressao = JasperFillManager.fillReport( relatorio , parametros,    jrRS );   
     
        //exibe o resultado   
        //JasperViewer viewer = new JasperViewer( impressao , true );   
        //viewer.show();   
                JasperExportManager.exportReportToPdfFile( "tested.pdf" );   
  
    }   
     
    public static void main(String[] args) {   
        try {   
            new relat_calculos().gerar( "Calculos.jasper" );   
        } catch (Exception e) {   
            e.printStackTrace();   
        }   
    }   
}  
import java.sql.Connection;import java.sql.DriverManager;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;import java.util.HashMap;import java.util.Map;
import net.sf.jasperreports.engine.JRException;
import net.sf.jasperreports.engine.JRResultSetDataSource;
import net.sf.jasperreports.engine.JasperCompileManager;
import net.sf.jasperreports.engine.JasperExportManager;
import net.sf.jasperreports.engine.JasperFillManager;
import net.sf.jasperreports.engine.JasperPrint;
import net.sf.jasperreports.engine.JasperReport;
import net.sf.jasperreports.engine.design.JasperDesign;
import net.sf.jasperreports.engine.xml.JRXmlLoader;
import net.sf.jasperreports.view.JasperViewer;

public class relat_calculos {

	private static final String url = "org.postgresql.Driver";
	private static final String driver = "jdbc:postgresql://localhost/saidas";
	private static final String login = "postgres";
	private static final String pwd = "4545";
   
	public relat_calculos() {
	}
   
	public void gerar( String layout ) throws JRException , SQLException, ClassNotFoundException {
		//gerando o jasper design
		JasperDesign desenho = JRXmlLoader.load( layout );
   
		//compila o relatório
		JasperReport relatorio = JasperCompileManager.compileReport( desenho );
   
		//estabelece conexão
		Class.forName( driver );
		Connection con = DriverManager.getConnection( url , login , pwd );
		Statement stm = con.createStatement();
		String query = "select * from calculos";
		ResultSet rs = stm.executeQuery( query );

		//implementação da interface JRDataSource para DataSource ResultSet
		JRResultSetDataSource jrRS = new JRResultSetDataSource( rs );
   
		//executa o relatório
		Map parametros = new HashMap();
		parametros.put("nota", new Double(10));
		JasperPrint impressao = JasperFillManager.fillReport( relatorio , parametros,    jrRS );
   
		//exibe o resultado
		//JasperViewer viewer = new JasperViewer( impressao , true );
		//viewer.show();
                JasperExportManager.exportReportToPdfFile( "tested.pdf" );

	}
   
	public static void main(String[] args) {
		try {
			new relat_calculos().gerar( "Calculos.jasper" );
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}