PDF添加水印

0.前提条件：需要导入itextpdf-5.5.13.jar

1.写一个为PDF添加水印的工具类，代码如下：

package com.tancong.mark;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;

import com.itextpdf.text.BaseColor;
import com.itextpdf.text.DocumentException;
import com.itextpdf.text.Rectangle;
import com.itextpdf.text.pdf.BaseFont;
import com.itextpdf.text.pdf.PdfContentByte;
import com.itextpdf.text.pdf.PdfGState;
import com.itextpdf.text.pdf.PdfReader;
import com.itextpdf.text.pdf.PdfStamper;

public class PDFWatermarkUtil {

    public static boolean addTextMark(String origination, String desination,
            String waterText, int x, int y, int fontSize) {

        FileInputStream fileInputStream = null;
        FileOutputStream fileOutputStream = null;
        try {
            fileInputStream = new FileInputStream(new File(origination));
            fileOutputStream = new FileOutputStream(new File(desination));

            return addTextMark(fileInputStream, fileOutputStream, waterText, x,
                    y, fontSize);

        } catch (Exception e) {
            e.printStackTrace();
        } finally {

            if (fileOutputStream != null) {
                try {
                    fileOutputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }

            if (fileInputStream != null) {
                try {
                    fileInputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }

        }

        return false;
    }
    
    

    private static boolean addTextMark(InputStream originFile,
            FileOutputStream targetFile, String waterText, int x, int y,
            int fontSize) {

        PdfReader reader = null;
        PdfStamper stamper = null;
        
        try {
            reader = new PdfReader(originFile);
            stamper = new PdfStamper(reader, targetFile);

            if (waterText == null)
                waterText = "没有定义水印";
            BaseFont font;
            if (waterText.getBytes().length == waterText.length()) {
                font = BaseFont.createFont();
            } else {
                font = BaseFont.createFont("STSongStd-Light", "UniGB-UCS2-H", true);
            }

            int total = reader.getNumberOfPages();
            PdfGState pg = new PdfGState();

            for (int i = 1; i <= total; i++) {

                Rectangle rect = reader.getPageSizeWithRotation(i);
                double width = rect.getWidth();
                double height = rect.getHeight();
                System.out.println(width + " " + height);
                if (width > height) {
                    width -= height;
                    height = width + height;
                    width = height - width;
                }

                PdfContentByte content = stamper.getOverContent(i);

                content.beginText();

                content.setColorFill(BaseColor.LIGHT_GRAY);

                content.setFontAndSize(font, fontSize);

                int xPosition = x;
                int yPosition = y;
                if (x > Math.floor(width))
                    xPosition = (int) Math.floor(width) - 520;
                if (Math.floor(width) < 1200.0D)
                    xPosition += 10;
                if (y > Math.floor(height))
                    y = (int) Math.floor(height) / 2;
                if (Math.floor(height) < 900.0D)
                    yPosition -= 60;

                xPosition += 50;
                yPosition -= 100;
                System.out.println(xPosition + " " + yPosition);

                pg.setFillOpacity(0.4F);

                content.setGState(pg);

                content.showTextAligned(0, waterText, xPosition, yPosition, 30.0F);

                content.endText();
            }
            
            return true;

        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                stamper.close();
            } catch (DocumentException | IOException e) {
                e.printStackTrace();
            }
            reader.close();
        }

        return false;
    }

}

2.写一个测试类测试代码

package com.tancong.mark;


public class TestPDFWatermark {
    
    public static void main(String[] args) {
        try {
            
            String origination = "D:\\费劲格林.pdf";    //    需要添加水印的PDF文件位置
            String desination = "D:\\费劲格林-after.pdf";    //    添加水印后PDF的文件位置
            String text = "Released";    //    水印文字
            
            //    1860,280为水印位置，66为文字大小
            PDFWatermarkUtil.addTextMark(origination, desination, text, 1860, 280, 66);    
            
        } catch (Exception e) {
        }
    }

}