Chamando o iReport pela aplicação

public void Imprimir(){
		
		try
		{
			System.setProperty("org.xml.sax.driver", "org.apache.xerces.parsers.SAXParser");
 			// First, load JasperDesign from XML and compile it into JasperReport
			JasperDesign jasperDesign = JasperManager.loadXmlDesign("SCPRE01_7.xml");
			JasperReport jasperReport = JasperManager.compileReport(jasperDesign);
			// Second, create a map of parameters to pass to the report.
			Map parameters = new HashMap();


			parameters.put("pstrCodCli", txtCodCli.getText());
			parameters.put("pstrAnoRef", txtCodSis.getText());
			parameters.put("pstrCodPla", txtCodLote.getText());

			// Third, get a database connection
			DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());
			Connection conn = Seu metodo que retorna a Conexao;
//			Fourth, create JasperPrint using fillReport() method
			JasperPrint jasperPrint = JasperManager.fillReport(jasperReport, parameters, conn);

			// You can use JasperPrint to create PDF
			//JasperManager.printReportToPdfFile(jasperPrint, "Dinamico.pdf");

			// Or to view report in the JasperViewer
			JasperViewer.viewReport(jasperPrint, true, true, "Teste");
		}
		catch(Exception exc)
		{
			exc.printStackTrace();
		}
	}