给pdf加水印

package com.form.test;

import java.io.FileOutputStream;
import java.io.IOException;

import com.itextpdf.text.BaseColor;
import com.itextpdf.text.Chunk;
import com.itextpdf.text.Document;
import com.itextpdf.text.DocumentException;
import com.itextpdf.text.Element;
import com.itextpdf.text.Font;
import com.itextpdf.text.PageSize;
import com.itextpdf.text.Paragraph;
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.PdfPCell;
import com.itextpdf.text.pdf.PdfPTable;
import com.itextpdf.text.pdf.PdfReader;
import com.itextpdf.text.pdf.PdfStamper;
import com.itextpdf.text.pdf.PdfWriter;

public class TestPriterWater {

public static void main(String[] args) throws Exception {
String pdfFilePath = "f:/itext-demo.pdf";
PdfReader pdfReader = new PdfReader("/home/xueqy/1.pdf");
// Get the PdfStamper object
PdfStamper pdfStamper = new PdfStamper(pdfReader
, new FileOutputStream(
"/home/xueqy/2.pdf"));
addWatermark(pdfStamper, "www.baidu.com");

pdfStamper.close();
}

private static void addWatermark(PdfStamper pdfStamper
, String waterMarkName) {
PdfContentByte content = null;
Rectangle pageRect = null;
PdfGState gs = new PdfGState();

try {
BaseFont base = BaseFont.createFont();
// 设置透明度为0.4
gs.setFillOpacity(0.4f);
gs.setStrokeOpacity(0.4f);
int toPage = pdfStamper.getReader().getNumberOfPages();
System.out.print(pdfStamper.getReader().getFileLength()+"    :" +toPage);
for (int i = 1; i <= toPage; i++) {
pageRect = pdfStamper.getReader().
getPageSizeWithRotation(i);
// 计算水印X,Y坐标
float x = pageRect.getWidth() / 2;
float y = pageRect.getHeight() / 2;
//获得PDF最顶层
content = pdfStamper.getOverContent(i);
content.saveState();
// set Transparency
content.setGState(gs);
content.beginText();
content.setColorFill(BaseColor.GRAY);
content.setFontAndSize(base, 24);
// content.setFontAndSize( 20);
content.showTextAligned(Element.ALIGN_CENTER
, waterMarkName, 300,
350, 30);
content.endText();
}
} catch (Exception ex) {
ex.printStackTrace();
} finally {
content = null;
pageRect = null;
}
}
}