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我在构建使用 pdfbox 的应用程序时遇到问题。当我从 IDE 运行该应用程序时（我使用 netbeans 8.1），该应用程序能够阅读带有 jbig2 图像的书籍（我在 pom.xml 中有 jbig2 的 maven 依赖项）。问题是当我构建应用程序时创建了一个胖罐。当我使用相同的输入 pdf 运行 fat jar 时，会出现以下错误：

“Cannot read JBIG2 image: jbig2-imageio is not installed”

评论该错误的线程似乎没有解决我的问题（他们说必须将 maven 依赖项添加到 pom，但该依赖项已经在我的 pom 上）。

我还检查了 jbig2 库类是否在 fat jar 中，所以我不知道发生了什么。

我已经在一个看起来像这样的小应用程序中隔离了这个问题：

public static void main( String[] args )
{
    String fileName = null;
    if( args.length == 0 )
    {
        fileName = "test.pdf";
    }
    else
    {
        fileName = args[0];
    }

    PdfDocumentWrapper doc = null;
    try
    {
        PdfboxFactory factory = new PdfboxFactory();
        doc = factory.createPdfDocumentWrapper();
        doc.loadPdf( fileName );
        for( int ii = 0; ii < doc.getNumberOfPages(); ii++ )
        {
            int pageNum = ii+1;
            System.out.println("\n\nProcessing page: " + pageNum +"\n---------------------------------");
            List<ImageWrapper> imageList = doc.getImagesOfPage(ii);

            int jj=0;
            for( ImageWrapper image: imageList )
            {
                jj++;
                System.out.println(String.format("  Page[%d]. Image[%d] -> bounds: %s",
                        pageNum, jj, image.getBounds().toString() ) );
            }
        }
    }
    catch( Exception ex )
    {
        ex.printStackTrace();
    }
    finally
    {
        if( doc != null )
        {
            try
            {
                doc.close();
            }
            catch( Exception ex )
            {
                ex.printStackTrace();
            }
        }
    }
}

我将整个孤立的示例项目放在这里（目的是帮助解决问题）： http ://www.frojasg1.com/20200504.PdfImageExtractor.zip

当我从 IDE 运行该应用程序时，它会产生以下输出：

Processing page: 1
---------------------------------
  Page[1]. Image[1] -> bounds: java.awt.Rectangle[x=17,y=33,width=442,height=116]
  Page[1]. Image[2] -> bounds: java.awt.Rectangle[x=53,y=513,width=376,height=124]
  Page[1]. Image[3] -> bounds: java.awt.Rectangle[x=101,y=250,width=285,height=5]
------------------------------------------------------------------------

当我从命令行运行应用程序时，它会给出以下输出：

$ java -jar ./PdfImageExtractor-v1.0-SNAPSHOT-all.jar


Processing page: 1
---------------------------------
may 04, 2020 3:40:18 PM org.apache.pdfbox.contentstream.PDFStreamEngine operatorException
GRAVE: Cannot read JBIG2 image: jbig2-imageio is not installed
may 04, 2020 3:40:18 PM org.apache.pdfbox.contentstream.PDFStreamEngine operatorException
GRAVE: Cannot read JBIG2 image: jbig2-imageio is not installed
may 04, 2020 3:40:18 PM org.apache.pdfbox.contentstream.PDFStreamEngine operatorException
GRAVE: Cannot read JBIG2 image: jbig2-imageio is not installed

有人知道为什么胖罐子无法读取 jbig2 图像吗？

4

2 回答 2

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我在 pdfbox 用户邮件列表中发布了相同的问题，答案如下：

Your fat-jar consists of several ImageIO libs. You are simply merging all files 
to one big jar and overwriting the config files of those ImageIO libs. Have a 
look at the directory "/META-INF/services". The files of the JBig" plugin are 
overwritten by files of another plugin. Either you merge those files or don't 
create one big jar of all deps.

和解决方案：

非常感谢，原来如此！

我已经能够创建这些 META-INF 文件：

$ find src/serviceManifests/
src/serviceManifests/
src/serviceManifests/META-INF
src/serviceManifests/META-INF/services
src/serviceManifests/META-INF/services/javax.imageio.spi.ImageReaderSpi
src/serviceManifests/META-INF/services/javax.imageio.spi.ImageWriterSpi

将它们与 ImageIO jar 中的合并

通过将这些行添加到 pom.xml：

<properties>
    <service.declaration.dir>src/serviceManifests</service.declaration.dir>
    <service.files.path>META-INF/services</service.files.path>
</properties>

<build>
    <resources>
    ...
        <resource>
            <directory>${service.declaration.dir}</directory>
            <includes>
                <include>${service.files.path}/*</include>
            </includes>
        </resource>
    ...
    </resources>
    ...
</build>

问题解决了。

于 2020-05-04T20:43:02.683 回答
0

添加 ImageIO.scanForPlugins(); ImageIO.scanForPlugins() 之前；也可以解决这个问题

于 2020-12-22T01:35:27.747 回答