Question

目前我正在尝试在java中打印一些pdf。使用的api是2.0版本中的Apache PDF Box。转换图像后，我将它们写入磁盘以节省内存。在下一步中，我再次阅读它们并在图像的头部写下标题。之后我又写了一遍。为了使用它们，我再次分开阅读它们。当我最后一次阅读它时，每200-300张图像会出现以下异常：

java.lang.IndexOutOfBoundsException: off < 0 || len < 0 || off+len > b.length || off+len < 0!
at javax.imageio.stream.MemoryCacheImageInputStream.read(MemoryCacheImageInputStream.java:100)
  at com.sun.imageio.plugins.common.SubImageInputStream.read(SubImageInputStream.java:61)
  at com.sun.imageio.plugins.common.InputStreamAdapter.read(InputStreamAdapter.java:47)
  at java.io.SequenceInputStream.read(SequenceInputStream.java:207)
  at java.util.zip.InflaterInputStream.fill(InflaterInputStream.java:238)
  at java.util.zip.InflaterInputStream.read(InflaterInputStream.java:158)
  at java.io.BufferedInputStream.fill(BufferedInputStream.java:246)
  at java.io.BufferedInputStream.read(BufferedInputStream.java:265)
  at java.io.FilterInputStream.read(FilterInputStream.java:83)
  at com.sun.imageio.plugins.png.PNGImageReader.decodePass(PNGImageReader.java:1104)
  at com.sun.imageio.plugins.png.PNGImageReader.decodeImage(PNGImageReader.java:1215)
  at com.sun.imageio.plugins.png.PNGImageReader.readImage(PNGImageReader.java:1330)
  at com.sun.imageio.plugins.png.PNGImageReader.read(PNGImageReader.java:1606)
  at javax.imageio.ImageIO.read(ImageIO.java:1448)
  at javax.imageio.ImageIO.read(ImageIO.java:1400)
  at my.code.Class.method()

我使用以下代码转换PDF：

            final HashMap<Integer, File> images = new HashMap<>();
            PDDocument document = PDDocument.load(sourceFile);

            PDFRenderer pdfRenderer = new PDFRenderer(document);
            final ExecutorService service = Executors.newFixedThreadPool(4);
            for (int page = 0; page < document.getNumberOfPages(); ++page)
            {
                final int finalPageNumber = page;
                Runnable r = () -> {
                    try
                    {
                        //Java could only print with 72 dpi so I'll use it
                        BufferedImage image = pdfRenderer.renderImageWithDPI(finalPageNumber, 72);
                        File imageFile = new File(sourceFile.getAbsolutePath() + "-" + (finalPageNumber + 1) + ".png");
                        ImageIO.write(image, "png", imageFile);
                        image.flush();
                        images.put(finalPageNumber, imageFile);
                    }
                    catch (final IOException e)
                    {
                        e.printStackTrace();
                    }
                };
                Thread t = new Thread(r, page + "");
                t.setName("" + page);
                service.submit(t);
            }

阅读时使用以下代码：

           // example url: /tmp/example.pdf-17.png
           Image i = ImageIO.read(url);

如何解决这个问题

提前致谢

Daniel Brenzel

修改

我忘了说我在图片上添加了一个标题：

                BufferedImage bimage = new BufferedImage(   simple.getValue().getWidth(null),
                                                                        simple.getValue().getHeight(null) + 50,
                                                                        BufferedImage.TYPE_INT_ARGB);
                Graphics bGr = bimage.createGraphics();
                bGr.setColor(Color.WHITE);
                bGr.fillRect(0, 0, bimage.getWidth(), bimage.getHeight());
                bGr.setFont(new Font("Arial", Font.PLAIN, 15));
                bGr.setColor(Color.BLACK);
                bGr.drawImage(simple.getValue(), 0, 50, null);
                bGr.drawString(entry.getValue(), 20, 20);
                try
                {
                    ImageIO.write(bimage, "PNG", new File(simple.getKey().toURI()));
                }
                catch (IOException | URISyntaxException e)
                {                       
                    e.printStackTrace();
                }
                bGr.dispose();

以下是文件的链接（可能会出现在每个页面上）：

Image wich throw the exception

PDF file wich is used (generated by Word2007)

Answer 1

我已经解决了我的问题。我没有等待Image的写作。现在我等待ExecutorService的完成，一切正常。

我认为释放资源存在问题，因为我已经在MemoryCacheImageInputStream第100行看到，抛出异常时每件事情都很好。

从磁盘

1 个答案: