爲什麼PrinterState始終爲空？

我需要對我的打印機有更多的控制權，然後我試圖獲得我的打印機的PrinterState，然後使用PrintStareReasons。我的代碼如下：爲什麼PrinterState始終爲空？

public void checkPrinterStatus(){ 

    try { 
     logger.info("Check -------------- "); 

     Thread.sleep(2000); 
    } catch (InterruptedException e) { 
     // TODO Auto-generated catch block 
     e.printStackTrace(); 
    } 

    PrintService printer = configParamPrintService.getPrintService(); 
    logger.info("State " + printer.isAttributeCategorySupported(PrinterState.class)); 
    Set<Attribute> attributes = getAttributes(printer); 
    for(Attribute attr : attributes){ 
     logger.info(attr.getName()); 
    } 



} 

public static Set<Attribute> getAttributes(PrintService printer) { 
    Set<Attribute> set = new LinkedHashSet<Attribute>(); 

    //get the supported docflavors, categories and attributes 
    Class<? extends Attribute>[] categories = (Class<? extends Attribute>[]) printer.getSupportedAttributeCategories(); 
    DocFlavor[] flavors = printer.getSupportedDocFlavors(); 
    AttributeSet attributes = printer.getAttributes(); 

    //get all the avaliable attributes 
    for (Class<? extends Attribute> category : categories) { 
     for (DocFlavor flavor : flavors) { 
      //get the value 
      Object value = printer.getSupportedAttributeValues(category, flavor, attributes); 

      //check if it's something 
      if (value != null) { 
       //if it's a SINGLE attribute... 
       if (value instanceof Attribute) 
        set.add((Attribute) value); //...then add it 

       //if it's a SET of attributes... 
       else if (value instanceof Attribute[]) 
        set.addAll(Arrays.asList((Attribute[]) value)); //...then add its childs 
      } 
     } 
    } 

    return set; 
}

谷歌搜索我也寫的getAttributes（）來獲取所有attribures但PrinterState不存在。

這是所有屬性的列表：

21.12.2015 16:48:56 INFO PrintWorker:142 - Check -------------- 
21.12.2015 16:48:58 INFO PrintWorker:151 - State false 
21.12.2015 16:48:58 INFO PrintWorker:154 - copies-supported 
21.12.2015 16:48:58 INFO PrintWorker:154 - finishings 
21.12.2015 16:48:58 INFO PrintWorker:154 - job-sheets 
21.12.2015 16:48:58 INFO PrintWorker:154 - job-sheets 
21.12.2015 16:48:58 INFO PrintWorker:154 - number-up 
21.12.2015 16:48:58 INFO PrintWorker:154 - number-up 
21.12.2015 16:48:58 INFO PrintWorker:154 - number-up 
21.12.2015 16:48:58 INFO PrintWorker:154 - number-up 
21.12.2015 16:48:58 INFO PrintWorker:154 - number-up 
21.12.2015 16:48:58 INFO PrintWorker:154 - number-up 
21.12.2015 16:48:58 INFO PrintWorker:154 - orientation-requested 
21.12.2015 16:48:58 INFO PrintWorker:154 - orientation-requested 
21.12.2015 16:48:58 INFO PrintWorker:154 - orientation-requested 
21.12.2015 16:48:58 INFO PrintWorker:154 - orientation-requested 
21.12.2015 16:48:58 INFO PrintWorker:154 - page-ranges 
21.12.2015 16:48:58 INFO PrintWorker:154 - media 
21.12.2015 16:48:58 INFO PrintWorker:154 - spool-data-destination

雖然

logger.info("State " + printer.isAttributeCategorySupported(PrinterState.class));

回報總是：

21.12.2015 16:48:58 INFO PrintWorker:151 - State false

我已經測試了下面的代碼在Linux和Windows（7 ），但沒有一個返回實際狀態。可能是什麼問題呢？打印機，驅動程序還是我的代碼？

來源

2015-12-21 Skizzo

重複。檢查了這一點：http://stackoverflow.com/questions/26985422/why-printerstate-always-returns-null 我會說，不要打擾太多，以獲得狀態，它似乎沒有正確實施 – delephin

相關： http://stackoverflow.com/questions/5567709/extended-printer-information-in-java – Jayan

isAttributeCategorySupported()返回true如果打印請求中的打印服務supports specifying a doc-level or job-level attribute in category否則返回false。

看一看the official oracle documentation會讓我的觀點更清晰

來源

2015-12-30 02:56:36

然後你告訴我，我的打印服務不支持這種屬性？然後我永遠不會獲得這些屬性？ – Skizzo

爲什麼PrinterState始終爲空？

回答

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