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

编程问答 2022-08-14

问题描述

主题：将文件添加到mainPDF后，尝试打开COsstream。换句话说，在将PDF文件添加到主PDF文件后，尝试将文本写入主PDF文档。我不想保存或关闭mainPDF，因为我计划一次又一次地添加更多的PDFFiles和更多的文本。就我而言，我尝试使用TreeMerge后打开PDPageContentStream contentStream。显然，主文件过早关闭了吗？ 向下滚动以在下面查看我的代码

自2014年左右以来，这个主题肯定存在很多麻烦： 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列表，并尝试解决此问题（下面的滚动）。我相信会有更多的初学者会遇到这个问题。

更多资源

这是我遇到问题的代码 

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.COSDocument最终定稿 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.COSDocument最终定稿 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)

解决方法

几件事可能导致此错误。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文件时问题消失了。但是，这是我的封面的问题。封面的COSStream干扰了合并的pdf文件。

我的封面上只有图像，没有文字。由于我仍然不知道的原因，这是导致错误的原因。一旦我为文本和空白文本设置了偏移量，程序就会进行编译。 请注意，PDImage之前已经具有偏移值。显然，这对于编译器来说还不够。

content1.newLineAtOffset（50，350）;

content1.setFont（PDType1Font.TIMES_ROMAN，14）;

content1.showText（“如果添加此代码，它将立即生效。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();
    }
javajavapdfbox