问题描述

使用pdfbox类库操作pdf文件时，遇到下面的报错信息：
java.io.IOException: Missing root object specification in trailer

PDFBox参考：
https://pdfbox.apache.org/
Apache PDFBox 库是一个开源的用于处理 PDF 文档的 Java 工具。

原因分析

目前看下来有两种原因：

1. pdf文件格式有损坏，无法读取
2. 使用的pdfbox版本有相关漏洞

解决方案

针对上面的 原因一，检查pdf文件格式，再操作。

针对上面的 原因二，可以通过升级pdfbox版本来解决：

Apache PDFBox 2.0.6 发布了，这个版本是基于 2.0.5 版本的增量式 bug 修复版本，包含了几个修复和小改进，在下面的release notes中就可以看到，修复了该问题：
Apache PDFBox 2.0.6 Release Notes

内容如下：

Sub-task
[PDFBOX-3302] - Explicit support for certification signatures
Bug
[PDFBOX-3313] - Java 9 InaccessibleObjectException
[PDFBOX-3318] - IllegalArgumentException in PDPageTree constructor: root cannot be null
[PDFBOX-3347] - COSName parsing doesn't handle ISO-8859-1 encoded bytes
[PDFBOX-3519] - COSName is not ascii
[PDFBOX-3545] - COSParser.parseXref failing if startXrefOffset over pdf size
[PDFBOX-3687] - PDFBox doesn't respect different setting of /DA at PDAnnotationWidget level to /DA at PDField level
[PDFBOX-3717] - java.io.IOException: Missing root object specification in trailer
[PDFBOX-3723] - FDFField.getValue() doesn't return the values in line with the Javadoc.
[PDFBOX-3724] - Wrong size in rendering of some artifacts
[PDFBOX-3726] - NPE when setting the field value in an AcroForm and the NormalAppearance entry exists but is COSNull
[PDFBOX-3727] - "premature EOF, image will be incomplete"
[PDFBOX-3728] - org.apache.pdfbox.cos.COSDictionary cannot be cast to org.apache.pdfbox.cos.COSStream
[PDFBOX-3731] - IOException: Found Token[kind=NAME, text=bind] but expected ND at offset 91
[PDFBOX-3732] - IllegalArgumentException when refreshing an appearance and no font resources are defined
[PDFBOX-3733] - image added to pdf by tool AddImageToPDF is turn-overed
[PDFBOX-3738] - Signature not visible on Acrobat
[PDFBOX-3739] - ImageWriterIterator.next() and ImageReaderIterator.next() can return null
[PDFBOX-3740] - Standard 14 and Encoding
[PDFBOX-3741] - usage of default colorspace not checked by preflight
[PDFBOX-3742] - Unknown dir object c='>' cInt=62 peek='>' peekInt=62
[PDFBOX-3743] - Running GC between signing and saving document closes stream
[PDFBOX-3745] - Wrong character width
[PDFBOX-3747] - CmapSubtable#getCharCodes provides values in random order
[PDFBOX-3748] - java.lang.UnsupportedOperationException: Kerning table version 0 format 2 not yet supported.
[PDFBOX-3750] - java.util.zip.DataFormatException when parsing a PDF
[PDFBOX-3751] - Flattening a pdf with refreshAppearances set to true causes a NullPointerException
[PDFBOX-3752] - PDVariableText text color changes to be the same as the background color after flattening
[PDFBOX-3753] - setting a RadioButton with export values does not update the appearance
[PDFBOX-3754] - Skip << >> in type1 font parser
[PDFBOX-3755] - ClassCastException in PDColor constructor: org.apache.pdfbox.cos.COSNull cannot be cast to org.apache.pdfbox.cos.COSNumber
[PDFBOX-3757] - TTFSubsetter scrambles PostScript names and unicode codepoints when subset contains diaeresis
[PDFBOX-3761] - Exception in thread "main" java.lang.NullPointerException
[PDFBOX-3769] - Cannot read JBIG2 image when JBIG2-Image-Decoder is in path
[PDFBOX-3775] - Merge documents fails due to IllegalArgumentException
[PDFBOX-3781] - Existing AcroForm default resources is overwritten by signing code
[PDFBOX-3783] - java.io.IOException: Expected root dictionary, but got this: COSNull{}
[PDFBOX-3784] - Inline image incorrectly parsed
[PDFBOX-3788] - java.lang.RuntimeException: java.io.IOException: Catalog cannot be found
[PDFBOX-3789] - Some text missing in rendering
[PDFBOX-3791] - Long rendering time
[PDFBOX-3837] - PDFBox does not maintain the font appearence of a field if it appears severraly in a PDF Form
Improvement
[PDFBOX-2684] - Javadoc for COSBase.setNeedToBeUpdate
[PDFBOX-3614] - Directly use the BouncyCastleProvider rather than installing it
[PDFBOX-3716] - Read images from byte array
[PDFBOX-3722] - make font cache error message less scary
[PDFBOX-3730] - Encapsulate outputStream into BufferedOutputStream in PDDocument.save()
[PDFBOX-3763] - Optimize SampledImageReader.getStencilImage()
[PDFBOX-3768] - Optimize SampledImageReader.from1Bit()
[PDFBOX-3770] - provide set of page indexes that have page label ranges
[PDFBOX-3772] - Add COSBoolean(false) as option in PDDocumentCatalog's getOpenAction
[PDFBOX-3779] - Add dpi and border parameter to PrintPDF command line utility