PDFBox not recognising pdf to be non printable

问题:

I am using PDFBox for validating a pdf document and one of the validation states that whether the pdf document is printable or not.

I use the following code to perform this operation:

PDDocument document = PDDocument.load("<path_to_pdf_file>");
System.out.println(document.getCurrentAccessPermission().canPrint());

but this is returning me true though when the pdf is opened, it shows the print icon disabled.

回答1:

Access permissions are integrated into a document by means of encryption.

Even PDF documents which don't ask for a password when opened in Acrobat Reader may be encrypted, they essentially are encrypted using a default password. This is the case in your PDF.

PDFBox determines the permissions of an encrypted PDF only while decrypting it, not already when loading a PDDocument. Thus, you have to try and decrypt the document before inspecting its properties if it is encrypted.

In your case:

PDDocument document = PDDocument.load("<path_to_pdf_file>");
if (document.isEncrypted())
{
    document.decrypt("");
}
System.out.println(document.getCurrentAccessPermission().canPrint());

The empty string "" represents the default password. If the file is encrypted using a different password, you'll get an exception here. Thus, catch accordingly.

PS: If you do not know all the passwords in question, you may still use PDFBox to check the permissions, but you have to work more low-level:

PDDocument document = PDDocument.load("<path_to_pdf_file>");
if (document.isEncrypted())
{
    final int PRINT_BIT = 3;
    PDEncryptionDictionary encryptionDictionary = document.getEncryptionDictionary();
    int perms = encryptionDictionary.getPermissions();
    boolean printAllowed = (perms & (1 << (PRINT_BIT-1))) != 0;
    System.out.println("Document encrypted; printing allowed?" + printAllowed);
}
else
{
    System.out.println("Document not encrypted; printing allowed? true");
}