如何在java中使用DocPrintJob进行打印

Question

帮我用DocPrintJob打印

我试过这段代码：

private void printToPrinter() {
    Object selection = null;
    FileInputStream textStream = null;
    try {
        textStream = new FileInputStream("G:\\Bill\\Bill1.pdf");
    } catch (java.io.FileNotFoundException e) {
        System.out.println("Error trying to find the print file created "
                + "in the printToPrinter() method");
    }
    DocFlavor flavor = DocFlavor.INPUT_STREAM.AUTOSENSE;
    Doc mydoc = new SimpleDoc(textStream, flavor, null);
    //Look up available printers.
    PrintService[] printers = PrintServiceLookup.lookupPrintServices(flavor, null);
    if (printers.length == 0) {
        // No printers found. Inform user.
        JOptionPane.showMessageDialog(this, 
                "No printers could be found on your system!", 
                "Error!", JOptionPane.ERROR_MESSAGE);
    } else {
        selection = JOptionPane.showInputDialog(this, 
                "Please select the desired printer:", "Print",
                JOptionPane.INFORMATION_MESSAGE, null, printers,
                PrintServiceLookup.lookupDefaultPrintService());
        if (selection instanceof PrintService) {
            PrintService chosenPrinter = PrintServiceLookup.lookupDefaultPrintService();
            //JOptionPane.showMessageDialog(null, "Default : "+chosenPrinter.getName());
            DocPrintJob printJob = chosenPrinter.createPrintJob();
            try {
                PrintRequestAttributeSet pras = new HashPrintRequestAttributeSet();
                pras.add(new Copies(1));
                printJob.print(mydoc, pras);
                JOptionPane.showMessageDialog(null, "Size = " + mydoc.toString());
                //(mydoc, pras);
                textStream.close();
            } catch (Exception e) {
                JOptionPane.showMessageDialog(this, 
                        "Error occured while attempting to print." + e, 
                        "Error!", JOptionPane.ERROR_MESSAGE);
            }
        }
    }
}

从此功能打印机无法打印，但打印机指示灯仅在我调用此功能时亮起