当输入控制器为空时，jasper报表为空

import net.sf.jasperreports.engine.*;
import net.sf.jasperreports.engine.data.JRBeanCollectionDataSource;
import java.util.*;

public class JasperReportExample {
    public static void main(String[] args) {
        try {
            // Load the compiled report design
            JasperReport jasperReport = JasperCompileManager.compileReport("path/to/your.jrxml");

            // Parameters for the report (if any)
            Map<String, Object> parameters = new HashMap<>();

            // Data source (example with a list of beans)
            List<YourDataBean> dataList = getData(); // Implement this method to fetch your data
            JRBeanCollectionDataSource dataSource = new JRBeanCollectionDataSource(dataList);

            // Fill the report with data
            JasperPrint jasperPrint = JasperFillManager.fillReport(jasperReport, parameters, dataSource);

            // Export the report to PDF (you can choose other formats like HTML, Excel, etc.)
            JasperExportManager.exportReportToPdfFile(jasperPrint, "path/to/output.pdf");

            System.out.println("报表生成成功！");
        } catch (JRException e) {
            e.printStackTrace();
        }
    }

    private static List<YourDataBean> getData() {
        // Implement this method to return your data as a list of beans
        return new ArrayList<>();
    }
}