300 // Not the same as default so proceed to get new PrintService.
301
302 // clear defaultPrintService
303 defaultPrintService = null;
304
305 if (printServices != null) {
306 for (int j=0; j<printServices.length; j++) {
307 if (defaultPrinter.equals(printServices[j].getName())) {
308 defaultPrintService = printServices[j];
309 break;
310 }
311 }
312 }
313
314 if (defaultPrintService == null) {
315 defaultPrintService = new Win32PrintService(defaultPrinter);
316 }
317 return defaultPrintService;
318 }
319
320 class PrinterChangeListener implements Runnable {
321 long chgObj;
322 PrinterChangeListener() {
323 chgObj = notifyFirstPrinterChange(null);
324 }
325
326 @Override
327 public void run() {
328 if (chgObj != -1) {
329 while (true) {
330 // wait for configuration to change
331 if (notifyPrinterChange(chgObj) != 0) {
332 try {
333 refreshServices();
334 } catch (SecurityException se) {
335 break;
336 }
337 } else {
338 notifyClosePrinterChange(chgObj);
339 break;
340 }
341 }
342 }
343 }
344 }
345
346 private native String getDefaultPrinterName();
347 private native String[] getAllPrinterNames();
348 private native long notifyFirstPrinterChange(String printer);
349 private native void notifyClosePrinterChange(long chgObj);
350 private native int notifyPrinterChange(long chgObj);
351 }
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300 // Not the same as default so proceed to get new PrintService.
301
302 // clear defaultPrintService
303 defaultPrintService = null;
304
305 if (printServices != null) {
306 for (int j=0; j<printServices.length; j++) {
307 if (defaultPrinter.equals(printServices[j].getName())) {
308 defaultPrintService = printServices[j];
309 break;
310 }
311 }
312 }
313
314 if (defaultPrintService == null) {
315 defaultPrintService = new Win32PrintService(defaultPrinter);
316 }
317 return defaultPrintService;
318 }
319
320 /* Windows provides *PrinterChangeNotification* functions that provides
321 information about printer status changes of the local printers but not
322 network printers.
323 Alternatively, Windows provides a way thro' which one can get the
324 network printer status changes by using WMI, RegistryKeyChange combination,
325 which is a slightly complex mechanism.
326 The Windows WMI offers an async and sync method to read thro' registry
327 via the WQL query. The async method is considered dangerous as it leaves
328 open a channel until we close it. But the async method has the advantage of
329 being notified of a change in registry by calling callback without polling for it.
330 The sync method uses the polling mechanism to notify.
331 RegistryValueChange cannot be used in combination with WMI to get registry
332 value change notification because of an error that may be generated because the
333 scope of the query would be too big to handle(at times).
334 Hence an alternative mechanism is choosen via the EnumPrinters by polling for the
335 count of printer status changes(add\remove) and based on it update the printers
336 list.
337 */
338 class PrinterChangeListener implements Runnable {
339 long prevRemotePrintersCount = 0;
340
341 PrinterChangeListener() {
342 prevRemotePrintersCount = GetRemotePrintersCount();
343 }
344
345 @Override
346 public void run() {
347 while(true) {
348 long currentRemotePrintersCount = GetRemotePrintersCount();
349 if(prevRemotePrintersCount != currentRemotePrintersCount) {
350
351 // updated the printers data
352 // printers list now contains both local and network printer data
353 refreshServices();
354
355 // store the current data for next comparison
356 prevRemotePrintersCount = currentRemotePrintersCount;
357 }
358 }
359 }
360 }
361
362 private native String getDefaultPrinterName();
363 private native String[] getAllPrinterNames();
364 private native long GetRemotePrintersCount();
365 }
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