使用 Apache PDFBox 替换 PDF 中的文本，弄乱某些内容

Question

我正在尝试使用 Apache PDFBox 使用以下代码对 PDF 执行文本替换。文本替换工作正常，但同时 pdf 的某些部分丢失了。您能帮我找出是什么原因造成的吗？调用replaceTextInSecond函数后，我只是执行下面的操作

document.save("filename.pdf");
document.close();

您能帮我找出原因吗？预先感谢！

private static PDDocument replaceTextInSecond(PDDocument document, String searchString, String replacement) {
        PDPage page = document.getPage(1);
        PDFStreamParser parser;
        try {
            parser = new PDFStreamParser(page);
            parser.parse();
            List<?> tokens = parser.getTokens();
            
            for (int j = 0; j < tokens.size(); j++) {
                Object next = tokens.get(j);
                if (next instanceof Operator) {
                    Operator op = (Operator) next;

                    String pstring = "";
                    int prej = 0;

                    if (op.getName().equals("Tj")) {
                        COSString previous = (COSString) tokens.get(j - 1);
                        String string = previous.getString();
                        //System.out.println("string :::: " +string);
                        string = string.replaceFirst(searchString, replacement);
                        previous.setValue(string.getBytes());
                    } else if (op.getName().equals("TJ")) {
                        COSArray previous = (COSArray) tokens.get(j - 1);
                        for (int k = 0; k < previous.size(); k++) {
                            Object arrElement = previous.getObject(k);
                            if (arrElement instanceof COSString) {
                                COSString cosString = (COSString) arrElement;
                                String string = cosString.getString();
                                //System.out.println("string :::: " +string);
                                if (j == prej) {
                                    pstring += string;
                                } else {
                                    prej = j;
                                    pstring = string;
                                }
                            }
                        }

                        if (searchString.equals(pstring.trim())) {
                            COSString cosString2 = (COSString) previous.getObject(0);
                            cosString2.setValue(replacement.getBytes());
                            int total = previous.size() - 1;
                            for (int k = total; k > 0; k--) {
                                previous.remove(k);
                            }
                        }
                    }
                }
            }
            PDStream updatedStream = new PDStream(document);
            OutputStream out = updatedStream.createOutputStream(COSName.FLATE_DECODE);
            ContentStreamWriter tokenWriter = new ContentStreamWriter(out);
            tokenWriter.writeTokens(tokens);
            out.close();
            page.setContents(updatedStream);
            //System.out.println("replaced " +searchString + " with " + replacement);
        }
                
        catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    return document;
    }

Answer 1

我发现了问题，

previous.setValue(string.getBytes());

就是罪魁祸首。保持代码为

if(string.contains(searchString)){
string = string.replaceFirst(searchString, replacement);
previous.setValue(string.getBytes());
}

解决了。看起来这与 pdf 的编码方式或其他相关。

无论如何，感谢您的帮助！ :)