jasper中的java JRBeanCollectionDataSource如何使用

Question

try {
    //Connecting to the MySQL database

    Class.forName("com.mysql.jdbc.Driver");
    conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/hospital", "root" ,"root");

    String report="C:\\Users\\DELL\\report10.jrxml";

    JasperReport jasperreport=JasperCompileManager.compileReport(report);
    patientDB DataBeanList = new patientDB();

    ArrayList<patientBean> dataList = DataBeanList.getDataBeanList();

    JRBeanCollectionDataSource beanColDataSource =
    new JRBeanCollectionDataSource(dataList);
    Map<String,Object> parameters = new HashMap<String,Object>();

    JasperPrint jp=JasperFillManager.fillReport(jasperreport, parameters,beanColDataSource);
    JasperViewer.viewReport(jp);

}
catch(Exception e)
{
    out.println(e);
}

我是jasper report中的新手，试图从bean类中获得价值，但什么也没发生。我用最后7天的时间来做这个