pdf加水印（给源文件加水印）附（生成一份新的加水印pdf）

package com.hand.hcm.dwp.controllers;



import java.awt.FontMetrics;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;

import javax.servlet.http.HttpServletResponse;
import javax.swing.JLabel;

import com.hand.hap.system.dto.ResponseData;
import com.hand.ocbm.constants.Constants;
import com.hand.ocbm.utils.PdfUtil;
import com.itextpdf.text.Element;
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;
import com.itextpdf.text.pdf.PdfWriter;
import org.apache.commons.io.IOUtils;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;


/***
 *@Name zjx
 *@data 2019/5/13 9:54
 *@version:1.0
 */
@Controller
public class TestwaterMark {

    @RequestMapping(value = "/dwp/pdf")
   public ResponseData pdf(HttpServletResponse response){
       waterMark("E://Teleforwarding.pdf", null, "CONTRACT",response);
       return new ResponseData(true);
   }
    private static int interval = -5;
    public static void waterMark(String inputFile,
                                 String outputFile, String waterMarkName,HttpServletResponse response) {
        PdfReader reader = null;
        PdfStamper stamper = null;
        FileOutputStream os = null;
        InputStream is = null;

        try {
            is = new FileInputStream(inputFile);
            reader = new PdfReader(is);
            os = new FileOutputStream(inputFile);
                    stamper = new PdfStamper(reader, os);
            BaseFont base = BaseFont.createFont("STSong-Light", "UniGB-UCS2-H",   BaseFont.EMBEDDED);

            Rectangle pageRect = null;
            PdfGState gs = new PdfGState();
            gs.setFillOpacity(0.3f);
            gs.setStrokeOpacity(0.4f);
            int total = reader.getNumberOfPages() + 1;

            JLabel label = new JLabel();
            FontMetrics metrics;
            int textH = 0;
            int textW = 0;
            label.setText(waterMarkName);
            metrics = label.getFontMetrics(label.getFont());
            textH = metrics.getHeight();
            textW = metrics.stringWidth(label.getText());

            PdfContentByte under;
            for (int i = 1; i < total; i++) {
                pageRect = reader.getPageSizeWithRotation(i);
                under = stamper.getOverContent(i);
                under.saveState();
                under.setGState(gs);
                under.beginText();
                under.setFontAndSize(base, 20);

                // 水印文字成30度角倾斜
                //你可以随心所欲的改你自己想要的角度
              for (int height = 0; height <4; ++ height) {
                    for (int width = interval + textW; width < pageRect.getWidth() + textW;
                         width = width + textW*2) {
                        under.showTextAligned(1
                                , waterMarkName, width,
                                height - textH, 30);
                    }
                }
            /*    for (int height = interval + textH; height < pageRect.getHeight();
                     height = height + textH*3) {
                    for (int width = interval + textW; width < pageRect.getWidth() + textW;
                         width = width + textW*2) {
                        under.showTextAligned(Element.ALIGN_LEFT
                                , waterMarkName, width - textW,
                                height - textH, 30);
                    }
                }*/
                for (int l = 0; l < 4; ++l) {
                    for (int j = 0; j < 10; ++j) {
                        under.showTextAligned(0, waterMarkName, 50.5F + (float) (l * 300), 40.0F + (float) (j * 250), 30);
                    }
                }
                // 添加水印文字
                under.endText();
            }
            stamper.close();
            reader.close();
            /*response.setContentType("application/pdf");
            response.setHeader("content-disposition", "attachment;filename="+"232");
            response.setCharacterEncoding(Constants.ENCODED_UTF_8);
            byte[]buff=new byte[1024*10];//可以自己 指定缓冲区的大小
            int len=0;
            OutputStream output = response.getOutputStream();
            while((len=is.read(buff))>-1)
            {
                output.write(buff,0,len);
            }*/
            //说三遍
            //一定不要忘记关闭流
            //一定不要忘记关闭流
            //一定不要忘记关闭流


           /* is.close();
            output.close();*/
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            IOUtils.closeQuietly(is);
            IOUtils.closeQuietly(os);
        }
    }
/*
    public static void main(String[] args) {
        waterMark("E/Teleforwarding+PCR001-For+Tunisia+TFN.pdf", "E:/te.pdf", "我是黑豆");

    }*/

}

https://blog.csdn.net/duan1309/article/details/81232300