PDFBox：COSStream 已关闭，无法读取。将 PDF 文件添加到 PDF。并回顾

Question

主题：在将文件添加到 mainPDF 后尝试打开 COSStream。换句话说，在您将 PDF 文件添加到您的主 PDF 文件之后，尝试将文本写入您的主 PDF 文档。我不想保存或关闭我的 mainPDF，因为我计划一次又一次地添加更多 PDF 文件和更多文本。就我而言，我试图在使用 TreeMerge 后打开 PDPageContentStream contentStream。显然，主要文件过早关闭？ 向下滚动以查看下面的代码

自 2014 年左右以来，这个话题肯定有很多麻烦： 我真的希望这些问题的答案能发布完整的代码。因此，我列出了类似问题的帖子并尝试解决此问题（滚动下方）。我相信更多的初学者会遇到这个问题。

• @mkl 和@community https://stackoverflow.com/a/49973366/14092356

  • 尝试使用newDoc.addPage(newDoc.importPage(doc.getPage(0))); 而不是newDoc.addPage(doc.getPage(1));
  • 记得关闭您在 mainPDF 中插入的新文件
  • 添加新文件时，请确保将它们分配给变量，这样垃圾收集也不会过早关闭它
  • 尝试将这些文件添加到 PDDocuments 的 ArrayList https://stackoverflow.com/a/61299092/14092356

• PDPages 在哪里被实例化很重要。 COSStream has been closed and cannot be read. Perhaps its enclosing PDDocument has been closed?

• 来自帖子：PDFBox IO Exception: COSStream has been closed and cannot be read。评论https://stackoverflow.com/a/55591429/14092356 - 对我不起作用：我在这里发布代码

  '''

    public void tableOfContents() throws IOException {
            String path1 = new File("Index1.pdf").getAbsoluteFile().toString();
            File file1 = new File(path1);
            String path2 = new File("Index2.pdf").getAbsoluteFile().toString();
            File file2 = new File(path2);
            PDFMergerUtility merger = new PDFMergerUtility();
            PDDocument combine = PDDocument.load(file1);
            PDDocument combine2 = PDDocument.load(file2);
            merger.appendDocument(mainDocument, combine);
            //combine.close();
            merger.appendDocument(mainDocument, combine2);
            merger.mergeDocuments();
            merger.mergeDocuments(MemoryUsageSetting.setupTempFileOnly());
    }
  

更多资源

• PDFBox COSStream closed before use
• java.io.IOException: COSStream has been closed and cannot be read. Perhaps its enclosing PDDocument has been closed?
• "IOException: COSStream has been closed and cannot be read" when trying to save PDF after adding page with PdfBox
• 合并大量 pdf 文件会很困难，因为您需要跟踪打开和关闭 https://issues.apache.org/jira/browse/PDFBOX-3901
• Reading a particular page from a PDF document using PDFBox

这是我的问题代码

import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.PDPage;
import org.apache.pdfbox.pdmodel.interactive.documentnavigation.outline.PDOutlineItem;

import java.io.IOException;

public class main {

    public static void main(String[] args) throws IOException {
        PDDocument document = new PDDocument();
        PDOutlineItem pagesOutline = new PDOutlineItem();

        for (int numberOfPages = 0; numberOfPages < 5; numberOfPages++) {
            //Creating a blank page
            PDPage blankPage = new PDPage();
            //Adding the blank page to the document
            document.addPage(blankPage);
        }

        ExampleImportingClass example = new ExampleImportingClass(document);

        document.save("exampleError.pdf");
        System.out.println("PDF created");
        document.close();
    }
}


import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.PDPage;
import org.apache.pdfbox.pdmodel.PDPageContentStream;
import org.apache.pdfbox.pdmodel.PDPageTree;
import org.apache.pdfbox.pdmodel.font.PDType1Font;
import org.apache.pdfbox.pdmodel.graphics.image.PDImageXObject;

import java.io.File;
import java.io.IOException;

public class ExampleImportingClass {
    private PDDocument document;

    public ExampleImportingClass(PDDocument document) throws IOException {
        this.document = document;
        page1();
        page2_3();
        page4();
    }

    public void page1() throws IOException {
        PDPage page1 = document.getPage(0);
        String path = new File("catPicture3.jpg").getAbsoluteFile().toString();
        PDImageXObject pdImage = PDImageXObject.createFromFile(path, document);
        PDPageContentStream content1 = new PDPageContentStream(document, page1);
        content1.beginText();
        content1.endText();
        content1.drawImage(pdImage, 50, 400,300,300);
        content1.close();
    }

    public void page2_3() throws IOException {

        String path1 = new File("Example1.pdf").getAbsoluteFile().toString();
        File file1 = new File(path1);
        String path2 = new File("Example2.pdf").getAbsoluteFile().toString();
        File file2 = new File(path2);

        PDPage page1 = document.getPage(0);
        PDPage page2 = document.getPage(2);

        PDPageTree mergePD = document.getPages();
        PDDocument doc1 = PDDocument.load(file1);
        PDDocument doc2 = PDDocument.load(file2);
        mergePD.insertAfter(doc1.getPage(0), page1);
        mergePD.insertAfter(doc2.getPage(0), page2);

    }


    public void page4() throws IOException {
        PDPage page = document.getPage(3);
        PDPageContentStream content1 = new PDPageContentStream(document, page);
        content1.beginText();
        content1.setFont(PDType1Font.TIMES_ROMAN, 14);
        content1.newLineAtOffset(50, 350);
        content1.showText("If we remove page4() method AND its not working, then its not ");
        content1.endText();
        content1.close();
    }

这是臭名昭著的错误堆栈跟踪：

2020 年 8 月 27 日晚上 11:10:48 org.apache.pdfbox.cos.COS 文档完成 警告：警告：您没有关闭 PDF 文档 2020 年 8 月 27 日 11:10:48 PM org.apache.pdfbox.cos.COS 文档完成 警告：警告：您没有关闭 PDF 文档

Exception in thread "main" java.io.IOException: COSStream has been closed and cannot be read. Perhaps its enclosing PDDocument has been closed?
    at org.apache.pdfbox.cos.COSStream.checkClosed(COSStream.java:154)
    at org.apache.pdfbox.cos.COSStream.createRawInputStream(COSStream.java:204)
    at org.apache.pdfbox.pdfwriter.COSWriter.visitFromStream(COSWriter.java:1219)
    at org.apache.pdfbox.cos.COSStream.accept(COSStream.java:475)
    at org.apache.pdfbox.cos.COSObject.accept(COSObject.java:158)
    at org.apache.pdfbox.pdfwriter.COSWriter.doWriteObject(COSWriter.java:526)
    at org.apache.pdfbox.pdfwriter.COSWriter.doWriteObjects(COSWriter.java:464)
    at org.apache.pdfbox.pdfwriter.COSWriter.doWriteBody(COSWriter.java:448)
    at org.apache.pdfbox.pdfwriter.COSWriter.visitFromDocument(COSWriter.java:1113)
    at org.apache.pdfbox.cos.COSDocument.accept(COSDocument.java:452)
    at org.apache.pdfbox.pdfwriter.COSWriter.write(COSWriter.java:1386)
    at org.apache.pdfbox.pdfwriter.COSWriter.write(COSWriter.java:1273)
    at org.apache.pdfbox.pdmodel.PDDocument.save(PDDocument.java:1357)
    at org.apache.pdfbox.pdmodel.PDDocument.save(PDDocument.java:1328)
    at org.apache.pdfbox.pdmodel.PDDocument.save(PDDocument.java:1316)
    at main.main(main.java:22)

Answer 1

有几件事可能会导致此错误。最终对我有用的是在流的开头添加偏移值和空白文本。所以我认为这是合并错误，因为当我停止合并新的 PDF 文件时问题就消失了。但是，我的封面有问题。封面页的 COSStream 干扰了 pdf 文件的合并。

我的封面只有一张图片，没有文字。由于我仍然不知道的原因，这是导致错误的原因。一旦我对文本和空白文本进行了偏移，程序就会编译。 请注意，PDImage 之前已经有一个偏移值。显然这对编译器来说还不够。

content1.newLineAtOffset(50, 350);

content1.setFont(PDType1Font.TIMES_ROMAN, 14);

content1.showText("如果我们添加这段代码，它现在可以工作了。奇怪");

public void page1() throws IOException {
        PDPage page1 = document.getPage(0);
        String path = new File("catPicture3.jpg").getAbsoluteFile().toString();
        PDImageXObject pdImage = PDImageXObject.createFromFile(path, document);
        PDPageContentStream content1 = new PDPageContentStream(document, page1);
        content1.beginText();

        content1.newLineAtOffset(50, 350);
        content1.setFont(PDType1Font.TIMES_ROMAN, 14);
        content1.showText("If we add this code it works now. Strange");

        content1.endText();
        content1.drawImage(pdImage, 50, 400,300,300);
        content1.close();
    }