如何禁止打印对话框

我每次打印都会弹出选择打印机的对话框，我应该如何让它自动选择系统默认的打印机，而不弹出打印对话框，下面是我的实现代码  
//获取工具箱
        Toolkit kit = panel.getToolkit();
        Properties props = new Properties();       
        //设置打印属性
        props.put("awt.print.printer", "durango");
        props.put("awt.print.numCopies", "1");        if (kit != null)
        {
            //获取工具箱自带的打印对象
            Graphics2D g2 = (Graphics2D) panel.getGraphics();
            g2.scale(0.8, 0.8);
         
            PrintJob printJob = kit.getPrintJob(frame, "Print Frame", props);
            if (printJob != null)
            {
                //获取打印对象的图形环境
                Graphics pg = printJob.getGraphics();
                if (pg != null)
                {
                    try
                    {
                        //打印该Panel及其所有的组件
                        panel.printAll(pg);
                    } finally
                    {
                        //注销图形环境
                        pg.dispose();
                    }
                }
                //结束打印作业
                printJob.end();
            }
        }