JARPrintPage.java

package bndtools.jareditor.internal;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.PrintStream;
import java.net.URI;

import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Status;
import org.eclipse.jface.resource.JFaceResources;
import org.eclipse.swt.SWT;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Text;
import org.eclipse.ui.forms.editor.FormEditor;
import org.eclipse.ui.forms.editor.FormPage;

public class JARPrintPage extends FormPage {

    private Text text;

    private boolean loaded = false;

    public JARPrintPage(FormEditor formEditor, String id, String title) {
        super(formEditor, id, title);
    }

    @Override
    public void createPartControl(Composite parent) {
        text = new Text(parent, SWT.NONE | SWT.H_SCROLL | SWT.V_SCROLL);
        text.setEditable(false);
        text.setFont(JFaceResources.getTextFont());
    }

    @Override
    public Control getPartControl() {
        return text;
    }

    @Override
    public void setActive(boolean active) {
        super.setActive(active);
        if (active && !loaded) {
            refresh();
        }
    }

    public void refresh() {
        URI uri = null;
        try {
            uri = URIHelper.retrieveFileURI(getEditorInput());
            if (uri != null) {
                text.setText(print(new File(uri)));
            }
        } catch (Exception e) {
            Plugin.getDefault().getLog().log(new Status(IStatus.ERROR, Plugin.PLUGIN_ID, 0, "Error outputing JAR content display.", e));
        } finally {
            loaded = true;
        }
    }

    private static String print(File file) throws Exception {
        try (Printer printer = new Printer()) {
            ByteArrayOutputStream bos = new ByteArrayOutputStream();
            printer.setOut(new PrintStream(bos, false, "UTF-8"));

            /* Printer.METATYPE throws an NPE */
            int options = Printer.VERIFY | Printer.MANIFEST | Printer.LIST | Printer.IMPEXP | Printer.USES | Printer.USEDBY | Printer.COMPONENT;

            printer.doPrint(file.getAbsolutePath(), options);
            return bos.toString("UTF-8");
        }
    }
}