我本质上是在尝试使用itext将tiff文件转换为pdf,这非常简单.

但是从我可以看到TiffImage.getTiffImage花费大量时间来执行较大的文件.

我的要求是使用FutureTask和ExecutorService提供多线程解决方案.这是我当前的代码：

import java.util.concurrent.Callable;

import com.itextpdf.text.Image;

import com.itextpdf.text.pdf.RandomAccessFileOrArray;

import com.itextpdf.text.pdf.codec.TiffImage;

public class ProcessTiffImage implements Callable{

RandomAccessFileOrArray tiffFile;

int pageNo;

public ProcessTiffImage(RandomAccessFileOrArray tiffFile, int pageNo){

this.tiffFile = tiffFile;

this.pageNo = pageNo;

}

public Image call() throws Exception {

Image image = TiffImage.getTiffImage(tiffFile, pageNo);

return image;

}

}

而convert方法是

public boolean convert(Document document) {

int numOfThreads = Runtime.getRuntime().availableProcessors() ;

ExecutorService service = Executors.newFixedThreadPool(numOfThreads );

List> taskList = new ArrayList>();

List imageList = new ArrayList();

for (int page = 1; page <= numOfPages; page++) {

FutureTask futureTask = new FutureTask(new ProcessTiffImage(tiffFile, page));

taskList.add(futureTask);

service.execute(futureTask);

}

try {

// Wait until all results are available

for (FutureTask future : taskList) {

imageList.add(future.get());

}

} catch (InterruptedException ex) {

ex.printStackTrace();

} catch (ExecutionException ex) {

ex.printStackTrace();

}

service.shutdown();

boolean success = generatePdf(document, imageList);

return success;

}

但是我在future.get()处收到了NullPointerException.问题是执行没有等待TiffImage.getTiffImage(tiffFile,pageNo)完成.因此,我无法创建图像列表.

任何帮助将不胜感激.

堆栈跟踪

java.util.concurrent.ExecutionException: java.lang.NullPointerException

at java.util.concurrent.FutureTask.report(FutureTask.java:122)

at java.util.concurrent.FutureTask.get(FutureTask.java:188)

at com.app.convertor.TiffParser.convert(TiffParser.java:107)

at com.app.start.TiffToPdf.main(TiffToPdf.java:40)

Caused by: java.lang.NullPointerException

Caused by: java.lang.NullPointerException

at com.itextpdf.text.pdf.codec.TIFFDirectory.getFieldAsLong(TIFFDirectory.java:467)

at com.itextpdf.text.pdf.codec.TIFFDirectory.getFieldAsLong(TIFFDirectory.java:477)

at com.itextpdf.text.pdf.codec.TiffImage.getTiffImage(TiffImage.java:124)

at com.itextpdf.text.pdf.codec.TiffImage.getTiffImage(TiffImage.java:106)

at com.app.processor.ProcessTiffImage.call(ProcessTiffImage.java:20)

at com.app.processor.ProcessTiffImage.call(ProcessTiffImage.java:1)

at java.util.concurrent.FutureTask.run(FutureTask.java:262)

at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)

at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)

at java.lang.Thread.run(Thread.java:744)