用java打印jframe

我想在单击按钮时打印jframe

所以我尝试了这个代码。如果我点击打印按钮，我会看到一个打印机对话框，当我告诉它打印时，它只打印一个空白文档，我不知道为什么。有什么帮助吗

public static class Printer implements Printable {
    final Component comp;

    public Printer(Component comp){
        this.comp = comp;
    }

    @Override
    public int print(Graphics g, PageFormat format, int page_index)
            throws PrinterException {
        if (page_index > 0) {
            return Printable.NO_SUCH_PAGE;
        }

        // get the bounds of the component
        Dimension dim = comp.getSize();
        double cHeight = dim.getHeight();
        double cWidth = dim.getWidth();

        // get the bounds of the printable area
        double pHeight = format.getImageableHeight();
        double pWidth = format.getImageableWidth();

        double pXStart = format.getImageableX();
        double pYStart = format.getImageableY();

        double xRatio = pWidth / cWidth;
        double yRatio = pHeight / cHeight;

        Graphics2D g2 = (Graphics2D) g;
        g2.translate(pXStart, pYStart);
        g2.scale(xRatio, yRatio);
        comp.paint(g2);

        return Printable.PAGE_EXISTS;
    }
}

在执行的按钮操作中

 JFrame yourComponent = new ODietListJFrame();
    PrinterJob pjob = PrinterJob.getPrinterJob();
    PageFormat preformat = pjob.defaultPage();
    preformat.setOrientation(PageFormat.LANDSCAPE);
    PageFormat postformat = pjob.pageDialog(preformat);

    //If user does not hit cancel then print.
    if (preformat != postformat) {
        //Set print component
        pjob.setPrintable(new Printer(yourComponent), postformat);
        if (pjob.printDialog()) {
            try {
                pjob.print();
            } catch (PrinterException ex) {
                Logger.getLogger(ODietListJFrame.class.getName()).log(Level.SEVERE, null, ex);
            }
        }
    }

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谢谢你的帮助。

首先，不要叫画画，叫打印我试过一次叫打印，又一次叫打印全部，但什么都没变你试过先让画框可见吗？不幸的是，我是初学者，你能告诉我如何让画框可见吗？如果你想使用setvisible，那么是的，我会这么做。