DesignViewerHotSwapper.java

package io.arleigh.reporting;

import java.awt.BorderLayout;
import java.lang.reflect.Field;
import java.util.Locale;
import java.util.ResourceBundle;
import javax.swing.JPanel;
import net.sf.jasperreports.engine.DefaultJasperReportsContext;
import net.sf.jasperreports.engine.JRReport;
import net.sf.jasperreports.engine.JasperReportsContext;
import net.sf.jasperreports.engine.convert.ReportConverter;
import net.sf.jasperreports.engine.design.JasperDesign;
import net.sf.jasperreports.engine.xml.JRXmlLoader;
import net.sf.jasperreports.swing.JRDesignViewer;
import net.sf.jasperreports.view.JasperDesignViewer;

public class DesignViewerHotSwapper {

  static final boolean isXML = true;
  static final Locale locale = Locale.getDefault();
  static final JasperReportsContext jasperReportsContext = DefaultJasperReportsContext
      .getInstance();

  static final JRViewerController controller = new JRViewerController(
      jasperReportsContext,
      locale,
      null
  );

  static final String filename = "FirstReport.jrxml";

  public static void main(String[] args) {

    JRDesignViewer viewer = createJRDesignViewer();
    controller.setReport(filename, isXML);

    try {
      JasperDesignViewer jdv = new JasperDesignViewer(jasperReportsContext, filename, isXML);
      Field f = jdv.getClass().getDeclaredField("pnlMain");
      f.setAccessible(true);
      JPanel panel = (JPanel) f.get(jdv);
      panel.remove(panel.getComponents().length - 1);
      panel.add(viewer, BorderLayout.CENTER);
      jdv.setVisible(true);

      new Thread(() -> {
        try {
          Thread.sleep(1000); // here's the hot reload >>>
          controller.loadReport("SecondReport.jrxml", isXML);
          controller.reload();

        } catch (Throwable t) {
          t.printStackTrace();
          System.exit(1);
        }
      }).start();
    } catch (Exception e) {
      e.printStackTrace();
      System.exit(1);
    }
  }

  private static JRDesignViewer createJRDesignViewer() {
    try {
      return new JRDesignViewer(filename, isXML) {
        @Override
        protected void initViewerContext(JasperReportsContext jasperReportsContext, Locale locale,
            ResourceBundle resBundle) {
          this.viewerContext = controller;
          setLocale(controller.getLocale());
          controller.addListener(this);
        }
      };
    } catch (Exception e) {
      e.printStackTrace();
      System.exit(1);
    }
    return null;
  }

  static class JRViewerController extends net.sf.jasperreports.swing.JRViewerController {

    JRViewerController(
        JasperReportsContext jasperReportsContext,
        Locale locale,
        ResourceBundle resBundle
    ) {
      super(jasperReportsContext, locale, resBundle);
      this.reloadSupported = true;
    }

    @Override
    public void setReport(String filename, boolean isXmlReport) {
      try {
        // if (isXmlReport) {
        JasperDesign jasperDesign = JRXmlLoader.load(filename);
        setReport(jasperDesign);
        // } else {
        // setReport((JRReport) JRLoader.loadObject(filename));
        // }
      } catch (Exception e) {
        e.printStackTrace();
        System.exit(1);
      }
    }

    void setReport(JRReport report) {
      this.jasperPrint = new ReportConverter(getJasperReportsContext(), report, false)
          .getJasperPrint();
    }
  }
}