use PdfSchema to update Meta data : Metadata « PDF « Java Tutorial

1. Java Tutorial
2. PDF
3. Metadata

import java.io.ByteArrayOutputStream;
import java.io.FileOutputStream;

import com.lowagie.text.Document;
import com.lowagie.text.Paragraph;
import com.lowagie.text.pdf.PdfWriter;
import com.lowagie.text.xml.xmp.DublinCoreSchema;
import com.lowagie.text.xml.xmp.PdfSchema;
import com.lowagie.text.xml.xmp.XmpArray;
import com.lowagie.text.xml.xmp.XmpSchema;
import com.lowagie.text.xml.xmp.XmpWriter;

public class MainClass {
  public static void main(String[] args) throws Exception {
    Document document = new Document();
    PdfWriter writer = PdfWriter.getInstance(document, new FileOutputStream("2.pdf"));
    ByteArrayOutputStream os = new ByteArrayOutputStream();
    XmpWriter xmp = new XmpWriter(os);
    XmpSchema dc = new DublinCoreSchema();
    XmpArray subject = new XmpArray(XmpArray.UNORDERED);
    subject.add("Metadata");
    dc.setProperty(DublinCoreSchema.SUBJECT, subject);
    xmp.addRdfDescription(dc);
    PdfSchema pdf = new PdfSchema();
    pdf.setProperty(PdfSchema.KEYWORDS, "Hello World, XMP, Metadata");
    pdf.setProperty(PdfSchema.VERSION, "1.4");
    xmp.addRdfDescription(pdf);
    xmp.close();
    writer.setXmpMetadata(os.toByteArray());
    document.open();
    document.add(new Paragraph("Hello World"));
    document.close();
  }
}