合并 PDF:错误:打开此文档文件时出错，因为它没有页面，因此无法打开

Question

我正在尝试合并pdf文件，但在打开文件时出错。我的代码是：

public void merge(){
byte[] pdf1 = tobyte("hello");
byte[] pdf2 = tobyte("world");
PDFMergerUtility merger = new PDFMergerUtility();
merger.addSource(new ByteArrayInputStream(pdf1));
merger.addSource(new ByteArrayInputStream(pdf2));
merger.setDestinationFileName("final.pdf");
merger.mergeDocuments();
}
static byte[] tobyte(String message) {
PDDocument doc = new PDDocument();
ByteArrayOutputStream baos = new ByteArrayOutputStream();
doc.save(baos);
return baos.toByteArray();
}

Answer 1

这是有效的代码

//Loading an existing PDF document
File file1 = new File("sample1.pdf");
PDDocument doc1 = null;
try {
doc1 = PDDocument.load(file1);
} catch (IOException e1) {
e1.printStackTrace();
}
File file2 = new File("sample2.pdf");
PDDocument doc2 = null;
try {
doc2 = PDDocument.load(file2);
} catch (IOException e1) {
e1.printStackTrace();
}
//Instantiating PDFMergerUtility class
PDFMergerUtility PDFmerger = new PDFMergerUtility();
//Setting the destination file
PDFmerger.setDestinationFileName("merged.pdf");
//adding the source files
PDFmerger.addSource(file1);
PDFmerger.addSource(file2);
//Merging the two documents
try {
PDFmerger.mergeDocuments();
} catch (COSVisitorException | IOException e) {
e.printStackTrace();
}
System.out.println("Documents merged");
//Closing the documents
try {
doc1.close();
} catch (IOException e) {
e.printStackTrace();
}
try {
doc2.close();
} catch (IOException e) {
e.printStackTrace();
}