用dw做网站首页步骤,推广链接赚钱,网页设计策划书,唐山微信小程序开发公司java文档中说PrinterJob类中的getPrinterJob()方法无论返回的打印机是否可用都不会返回一个null值。我查阅过一些文献有介绍说可以用getPrintService()方法测试返回的数值是否为null来...java文档中说PrinterJob类中的getPrinterJob()方法无论返回的打印机是否可用都不会返回一…java文档中说PrinterJob类中的getPrinterJob()方法无论返回的打印机是否可用都不会返回一个null值。我查阅过一些文献有介绍说可以用getPrintService()方法测试返回的数值是否为null来...java文档中说PrinterJob类中的getPrinterJob()方法无论返回的打印机是否可用都不会返回一个null值。我查阅过一些文献有介绍说可以用getPrintService()方法测试返回的数值是否为null来判断打印机是否可用。但是我不明白的是在什么情况下打印机不可用高分求解详细的解答。java文档参考原文PrinterJob java.awt.print.PrinterJob.getPrinterJob()Creates and returns a PrinterJob which is initially associated with the default printer. If no printers are available on the system, a PrinterJob will still be returned from this method, but getPrintService() will return null, and calling print with this PrinterJob might generate an exception. Applications that need to determine if there are suitable printers before creating a PrinterJob should ensure that the array returned from lookupPrintServices is not empty.相关文档原文参考One point you should keep in mind is that sometimes a printer may not be available on the machine on which your code is running.In this case the getPrintService() method will return null,so its a good idea to call the method and test the reference that is returned,even if you dont want to obtain details of the printer.请排除打印机损坏的情况。展开
