jasperreport怎么调用子报表，在页面上显示

这是报表所要的参数

Map parameters = new HashMap();
parameters.put("monthTime", monthTime);
parameters.put("factoryNo", factoryNo);
parameters.put("factoryName", factoryName);
parameters.put("REPORT_CONNECTION",   this.getConnection());//把子表连接作为参数传递
		parameters.put("SUBREPORT_DIR",application.getRealPath("/WEB-INF/jasper/")+"\\");

生成报表

InputStream reportStream = application.getResourceAsStream("produce_month_report.jasper");
			byte[] bytes = JasperRunManager.runReportToPdf(reportStream, paras,
					con);
			response.setContentType("application/pdf;charset=gb2312");
			response.setContentLength(bytes.length);
			response.getOutputStream().write(bytes, 0, bytes.length);

这样运行的话会报

net.sf.jasperreports.engine.JRException: Could not load object from location : produce_month_report_main.jasper

请知道的指点下，怎么把produce_month_report_main.jasper这个子报表加载到流中
如果没有子报表的报表能正常运行
谢谢