pdfbox应用程序胖子给出了“无法读取JBIG2映像：未安装jbig2-imageio”，但可以从IDE正常运行

Question

[我在构建使用pdfbox的应用程序时遇到了问题。当我从IDE（我使用netbeans 8.1）运行它时，该应用程序能够读取带有jbig2图像的书籍（我在pom.xml中具有jbig2的maven依赖项）。问题是当我构建创建胖子的应用程序时。当我使用相同的输入pdf运行胖罐时，出现以下错误：

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

注释该错误的线程似乎并不能解决我的问题（他们说，必须向pom添加一个maven依赖项，但是该依赖项已经在我的pom上。

我还检查了jbig2库类是否在胖子罐中，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，它将产生以下输出：

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，它提供以下输出：

$ 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

有人知道为什么胖子无法读取jbig2图像吗？

Answer 1

我在pdfbox用户邮件列表中发布了相同的问题，这是答案：

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.

以及解决方案：

非常感谢，就是这样！

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>

问题已解决。