使用 PDFBox 加水印 [英] Watermarking with PDFBox

问题描述

我正在尝试专门使用 PDFBox 向 PDF 添加水印.我已经能够让图像出现在每个页面上，但它失去了背景透明度，因为它看起来好像 PDJpeg 将它转换为 JPG.也许有一种方法可以使用 PDXObjectImage 来做到这一点.

I am trying to add a watermark to a PDF specifically with PDFBox. I've been able to get the image to appear on each page, but it loses the background transparency because it appears as though PDJpeg converts it to a JPG. Perhaps there's a way to do it using PDXObjectImage.

以下是我目前所写的:

public static void watermarkPDF(PDDocument pdf) throws IOException
{
    // Load watermark
    BufferedImage buffered = ImageIO.read(new File("C:\PDF_Test\watermark.png"));
    PDJpeg watermark = new PDJpeg(pdf, buffered);

    // Loop through pages in PDF
    List pages = pdf.getDocumentCatalog().getAllPages();
    Iterator iter = pages.iterator();
    while(iter.hasNext())
    {
        PDPage page = (PDPage)iter.next();

        // Add watermark to individual page
        PDPageContentStream stream = new PDPageContentStream(pdf, page, true, false);
        stream.drawImage(watermark, 100, 0);
        stream.close();
    }

    try 
    {
        pdf.save("C:\PDF_Test\watermarktest.pdf");
    } 
    catch (COSVisitorException e) 
    {
        e.printStackTrace();
    }
}

推荐答案

UPDATED ANSWER(更好的版本，带有简单的水印方式，感谢下面的评论员和@okok 提供了他的答案)

UPDATED ANSWER (Better version with easy way to watermark, thanks to the commentators below and @okok who provided input with his answer)

如果您使用的是 PDFBox 1.8.10 或更高版本，您可以轻松地为 PDF 文档添加水印，并更好地控制需要添加水印的页面.假设您有一个带有水印图像的一页 PDF 文档，您可以将其覆盖在要添加水印的文档上，如下所示.

If you are using PDFBox 1.8.10 or above, you can add watermark to your PDF document easily with better control over what pages needs to be watermarked. Assuming you have a one page PDF document that has the watermark image, you can overlay this on the document you want to watermark as follows.

使用 1.8.10 的示例代码

import java.util.HashMap;
import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.util.Overlay;

public class TestPDF {
    public static void main(String[] args) throws Exception{
            PDDocument realDoc = PDDocument.load("originaldocument.pdf"); 
            //the above is the document you want to watermark                   

            //for all the pages, you can add overlay guide, indicating watermark the original pages with the watermark document.
            HashMap<Integer, String> overlayGuide = new HashMap<Integer, String>();
            for(int i=0; i<realDoc.getPageCount(); i++){
                overlayGuide.put(i+1, "watermark.pdf");
                //watermark.pdf is the document which is a one page PDF with your watermark image in it. Notice here that you can skip pages from being watermarked.
            }
            Overlay overlay = new Overlay();
            overlay.setInputPDF(realDoc);
            overlay.setOutputFile("final.pdf");
            overlay.setOverlayPosition(Overlay.Position.BACKGROUND);
            overlay.overlay(overlayGuide,false);
           //final.pdf will have the original PDF with watermarks.

使用 PDFBox 2.0.0 候选版本的示例

import java.io.File;
import java.util.HashMap;
import org.apache.pdfbox.multipdf.Overlay;
import org.apache.pdfbox.pdmodel.PDDocument;

public class TestPDF {

    public static void main(String[] args) throws Exception{        
        PDDocument realDoc = PDDocument.load(new File("originaldocument.pdf"));
        //the above is the document you want to watermark
        //for all the pages, you can add overlay guide, indicating watermark the original pages with the watermark document.

        HashMap<Integer, String> overlayGuide = new HashMap<Integer, String>();
        for(int i=0; i<realDoc.getNumberOfPages(); i++){
            overlayGuide.put(i+1, "watermark.pdf");
            //watermark.pdf is the document which is a one page PDF with your watermark image in it. 
            //Notice here, you can skip pages from being watermarked.
        }
        Overlay overlay = new Overlay();
        overlay.setInputPDF(realDoc);
        overlay.setOutputFile("final.pdf");
        overlay.setOverlayPosition(Overlay.Position.BACKGROUND);
        overlay.overlay(overlayGuide);      
    }
}

如果您想使用新包 org.apache.pdfbox.tools.OverlayPDF 进行叠加，您可以这样做.(感谢下面的海报)

If you want to use the new package org.apache.pdfbox.tools.OverlayPDF for overlays you can do this way. (Thanks the poster below)

String[] overlayArgs = {"C:/Examples/foreground.pdf", "C:/Examples/background.pdf", "C:/Examples/resulting.pdf"};
OverlayPDF.main(overlayArgs);
System.out.println("Overlay finished.");

<小时>

旧答案效率低下，不推荐.

好吧，OP 询问如何在 PDFBox 中执行此操作，第一个答案看起来像是使用 iText 的示例.在 PDFBox 中创建水印非常简单.诀窍是，您应该有一个带有水印图像的空 PDF 文档.然后你所要做的就是将这个水印文档覆盖在你想要添加水印的文档上.

Well, OP asked how to do it in PDFBox, the first answer looks like an example using iText. Creating a watermark in PDFBox is really simple. The trick is, you should have an empty PDF document with the watermark image. Then all you have to do is Overlay this watermark document on the document that you want to add the watermark to.

PDDocument watermarkDoc = PDDocument.load("watermark.pdf");
//Assuming your empty document with watermark image in it.

PDDocument realDoc = PDDocument.load("document-to-be-watermarked.pdf");
//Let's say this is your document that you want to watermark. For example sake, I am opening a new one, you would already have a reference to PDDocument if you are creating one

Overlay overlay = new Overlay();
overlay.overlay(realDoc,watermarkDoc);
watermarkDoc.save("document-now-watermarked.pdf");

注意:您应该确保两个文档中的页数相匹配.否则，您最终会得到一个页数与页数最少的文档相匹配的文档.您可以操作水印文档并复制页面以匹配您的文档.

Caution: You should make sure you match the number of pages in both document..Otherwise, you would end up with a document with number of pages matching the one which has least number of pages. You can manipulate the watermark document and duplicate the pages to match your document.

希望这会有所帮助.

这篇关于使用 PDFBox 加水印的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！