Connection leak while generating jasper report

answered 2020-12-19 10:03:02 +0800

Jasonec
1

I've found a solution creating a custom component based on ZK Jasperreport component which open sql Connection only when needed and close it inmmediately after, avoiding connection leaks. You have to create the component class (which I named JasperreportUtil) and define it on lang-addon.xml file. After that, you have to change your Composer (or zscript) to use our custom component class instead of ZK Jasperreport and avoid call the method setDataConnection because now the connection will be set internally. Finally, you have to change the <jasperreport> tag name in zul files by the new one (I named <jasperreportutil>).

Here is the source code of JasperreportUtil component class:

import java.sql.Connection;
import org.zkoss.util.media.Media;
import org.zkoss.zkex.zul.Jasperreport;

/**
 * Component class based on {@link Jasperreport} which avoids connection leaks.
 * @author Jason Jijón
 */
public class JasperreportUtil extends Jasperreport {

    @Override
    public Object getExtraCtrl() {
        return new ExtraCtrl();
    }

    @Override
    @Deprecated
    public void setDataConnection(Connection connection) {
        throw new UnsupportedOperationException("Don't use this method because connection is assigned internally.");
    }

    protected class ExtraCtrl extends Jasperreport.ExtraCtrl {

        @Override
        public Media getMedia(String pathInfo) {
            try (Connection con = YourConnectionProvider.getConnection()) {
                JasperreportUtil.super.setDataConnection(con);
                return super.getMedia(pathInfo);
            } catch(SQLException e) {                    
                throw new RuntimeException(e);
            } finally {
                JasperreportUtil.super.setDataConnection(null);
            }
        }    
    }
}

The lang-addon.xml file could be the following:

<?xml version="1.0" encoding="windows-1250"?>
<language-addon>
    <addon-name>example</addon-name>
    <language-name>xul/html</language-name>

    <component>
        <component-name>jasperreportutil</component-name>
        <component-class>com.example.components.JasperreportUtil</component-class>
        <widget-class>zkex.utl.Jasperreport</widget-class>
        <mold>
            <mold-name>default</mold-name>
            <mold-uri>mold/jasperreport.js</mold-uri>
        </mold>
    </component>
</language-addon>