[移动开发]pdf 加多列水印

效果如图

demo代码

package test;


import com.itextpdf.text.DocumentException;
import com.itextpdf.text.Element;
import com.itextpdf.text.Rectangle;
import com.itextpdf.text.pdf.*;

import java.awt.*;
import java.io.*;

import java.util.*;
import java.util.List;

import javax.swing.*;

/**
 * 图片加水印，设置透明度
 */
public class WatermarkMainTest {

    public static void main(String[] args) throws DocumentException, IOException {
        List<String> watermarkNames = new ArrayList<>();
		watermarkNames.add("xx公司专用");
		watermarkNames.add("xxx|业务部");
		watermarkNames.add("2022-12-11 22:33");
		try {
            setWatermark2("C:\\Users\\demo\\Desktop\\out.pdf", "C:\\Users\\demo\\Desktop\\read.pdf",watermarkNames);
		} catch (Exception e) {
			e.printStackTrace();
		}

    }

    /**
     *
     * @param out 输出文件的位置
     * @param input 原PDF位置
     * @param waterMarkNames 水印内容
     * @throws DocumentException
     * @throws IOException
     */
    public static void setWatermark2(String out,  String input, List<String> waterMarkNames)
            throws Exception {
        PdfReader reader = null;
        PdfStamper stamper = null;
        try {
            File file2 = new File(out);
            if (file2.exists()) {
                file2.delete();
            }
            BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(file2));
            reader = new PdfReader(input);
            stamper = new PdfStamper(reader, bos);
            // 获取总页数 +1, 下面从1开始遍历
            int total = reader.getNumberOfPages() + 1;
            // 使用classpath下面的字体库
            com.itextpdf.text.pdf.BaseFont base = null;
            // 区分Linux系统与windows系统
            String fontsPath = "C:/Windows/Fonts/simsun.ttc";//中文字体路径
            base = com.itextpdf.text.pdf.BaseFont.createFont(fontsPath+",1", com.itextpdf.text.pdf.BaseFont.IDENTITY_H, com.itextpdf.text.pdf.BaseFont.NOT_EMBEDDED);

            // 间隔
            int interval = -10;
            // 获取水印文字的高度和宽度
            int textH = 0, textW = 0;
            JLabel label = new JLabel();
            label.setText(waterMarkNames.get(0));
            FontMetrics metrics = label.getFontMetrics(label.getFont());
            //textH = metrics.getHeight();
            //textW = metrics.stringWidth(label.getText());
            // 根据自己需要可以调整水印的间隔
            textH = 16;
            textW = 182;
            System.out.println("textH: " + textH);
            System.out.println("textW: " + textW);

            // 设置水印透明度
            PdfGState gs = new PdfGState();
            gs.setFillOpacity(0.3f);
            gs.setStrokeOpacity(0.3f);

            Rectangle pageSizeWithRotation = null;
            PdfContentByte content = null;
            for (int i = 1; i < total; i++) {
                // 在内容上方加水印
                content = stamper.getOverContent(i);
                // 在内容下方加水印
                // content = stamper.getUnderContent(i);
                content.saveState();
                content.setGState(gs);

                // 设置字体和字体大小
                content.beginText();
                content.setFontAndSize(base, 9);

                // 获取每一页的高度、宽度
                pageSizeWithRotation = reader.getPageSizeWithRotation(i);
                float pageHeight = pageSizeWithRotation.getHeight();
                float pageWidth = pageSizeWithRotation.getWidth();

                // 根据纸张大小多次添加， 水印文字成30度角倾斜，根据自己的需要，对应的值调整
                for (int height = interval + textH; height < pageHeight; height = height + textH * 6) {
                    for (int width = interval + textW; width < pageWidth + textW; width = width + textW * 1) {
                        int len=0;
                        for (String waterMarkName : waterMarkNames) {
                            content.showTextAligned(Element.ALIGN_MIDDLE, waterMarkName, width - textW-90, height - textH-len*12, 30);
                            len++;
                        }
                    }
                }
                content.endText();
            }
        } catch (Exception e) {
            // 日志处理
           // log.error("水印异常--->waterName="+waterMarkNames.toString(),e);
            throw new Exception("水印异常");
        }finally {
            // 关流
            if(stamper != null){
                stamper.close();
            }
            if(reader != null){
                reader.close();
            }
        }
    }
}

?