/**
 * 
 */
package test;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;

import com.itextpdf.text.Document;
import com.itextpdf.text.pdf.BaseFont;
import com.itextpdf.text.pdf.PdfContentByte;
import com.itextpdf.text.pdf.PdfImportedPage;
import com.itextpdf.text.pdf.PdfReader;
import com.itextpdf.text.pdf.PdfWriter;




/**
 * @author xzx
 * 
 *         2019年5月5日
 *
 */
public class MergePDF {
	private static String USER_PASS = "123";
	private static String OWNER_PASS = "321";

	public static void main(String[] args) {
		try {
			List<InputStream> pdfs = new ArrayList<InputStream>();
			pdfs.add(new FileInputStream("D:\\Test.pdf"));
//			pdfs.add(new FileInputStream("D:\\Test1.pdf"));
			OutputStream output = new FileOutputStream("d:\\encry.pdf");
			MergePDF.concatPDFs(pdfs, output, true);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	public static void concatPDFs(List<InputStream> streamOfPDFFiles, OutputStream outputStream, boolean paginate) {

		Document document = new Document();
		try {
			List<InputStream> pdfs = streamOfPDFFiles;
			List<PdfReader> readers = new ArrayList<PdfReader>();
			int totalPages = 0;

			// Create Readers for the pdfs.
			for (InputStream pdf : pdfs) {
				PdfReader pdfReader = new PdfReader(pdf);
				readers.add(pdfReader);
				totalPages += pdfReader.getNumberOfPages();
			}
			// Create a writer for the outputstream
			PdfWriter writer = PdfWriter.getInstance(document, outputStream);
			writer.setEncryption(USER_PASS.getBytes(), OWNER_PASS.getBytes(), PdfWriter.ALLOW_SCREENREADERS,PdfWriter.STANDARD_ENCRYPTION_128);
			document.open();
			BaseFont bf = BaseFont.createFont(BaseFont.HELVETICA, BaseFont.CP1252, BaseFont.NOT_EMBEDDED);
			PdfContentByte cb = writer.getDirectContent(); // Holds the PDF
			// data

			PdfImportedPage page;
			int currentPageNumber = 0;
			int pageOfCurrentReaderPDF = 0;

			// Loop through the PDF files and add to the output.
			for (PdfReader pdfReader : readers) {
				// Create a new page in the target for each source page.
				while (pageOfCurrentReaderPDF < pdfReader.getNumberOfPages()) {
					document.newPage();
					pageOfCurrentReaderPDF++;
					currentPageNumber++;
					page = writer.getImportedPage(pdfReader, pageOfCurrentReaderPDF);
					cb.addTemplate(page, 0, 0);

					// Code for pagination.
					if (paginate) {
						cb.beginText();
						cb.setFontAndSize(bf, 9);
						cb.showTextAligned(PdfContentByte.ALIGN_CENTER, "" + currentPageNumber + " of " + totalPages,
								520, 5, 0);
						cb.endText();
					}
				}
				pageOfCurrentReaderPDF = 0;
			}
			outputStream.flush();
			document.close();
			outputStream.close();
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			if (document.isOpen())
				document.close();
			try {
				if (outputStream != null)
					outputStream.close();
			} catch (IOException ioe) {
				ioe.printStackTrace();
			}
		}
	}
}