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# PDFBox - PDF File References

- File Specification
- File Attachments

## File Specification

See package:org.pdfbox.pdmodel.common.filespecification
See example:EmbeddedFiles

A PDF can contain references to external files via the file system or a URL to a remote location. It is also possible to embed a binary file into a PDF document.

There are two classes that can be used when referencing a file. PDSimpleFileSpecification is a simple string reference to a file(e.g. "./movies/BigMovie.avi"). The simple file specification does not allow for any parameters to be set. The PDComplexFileSpecification is more feature rich and allows for advanced settings on the file reference.

It is also possible to embed a file directly into a PDF. Instead of setting the file attribute of the PDComplexFileSpecification, the EmbeddedFile attribute can be used instead.

## File Attachments

PDF documents can contain file attachments that are accessed from the Document->File Attachments menu. PDFBox allows attachments to be added and extracted to PDF documents. Attachments are part of the named tree that is attached to the document catalog.

            PDEmbeddedFilesNameTreeNode efTree = new PDEmbeddedFilesNameTreeNode();

            //first create the file specification, which holds the embedded file
            PDComplexFileSpecification fs = new PDComplexFileSpecification();
            fs.setFile( "Test.txt" );
            InputStream is = ...;
            PDEmbeddedFile ef = new PDEmbeddedFile(doc, is );
            //set some of the attributes of the embedded file
            ef.setSubtype( "test/plain" );
            ef.setSize( data.length );
            ef.setCreationDate( new GregorianCalendar() );
            fs.setEmbeddedFile( ef );

            //now add the entry to the embedded file tree and set in the document.
            Map efMap = new HashMap();
            efMap.put( "My first attachment", fs );
            efTree.setNames( efMap );
            //attachments are stored as part of the "names" dictionary in the document catalog
            PDDocumentNameDictionary names = new PDDocumentNameDictionary( doc.getDocumentCatalog() );
            names.setEmbeddedFiles( efTree );
            doc.getDocumentCatalog().setNames( names );