自适应文字长度水印
1.效果图
2.代码
2.1.pom
com.itextpdf itextpdf 5.5.13.1 com.itextpdf itext-asian 5.2.0 2.2.水印工具类（自动调节文字个数）
import cn.hutool.core.date.DateUtil;import com.itextpdf.text.Element;import com.itextpdf.text.Rectangle;import com.itextpdf.text.pdf.*;import javax.swing.*;import java.awt.*;import java.io.*;import java.net.URL;import java.nio.file.Files;import java.nio.file.Paths;import static com.shinkeer.common.utils.SecurityUtils.getUsername;public class PdfWatermarkUtil { public static void main(String[] args) { PdfWatermarkLocal("C:\\Users\\Pictures\\pdf水印测试.pdf", "C:\\Users\\Pictures\\pdf（加）.pdf", "一二三四五六七八九十十九八七六五四三二一"); } public static void main2(String[] args) throws Exception { File file = new File("C:\\Users\\Pictures\\pdf水印测试.pdf"); InputStream inputStream = file.toURL().openStream(); InputStream stream = PdfWatermarkTool.addPdfWatermark(inputStream, "这是水印" + DateUtil.now(), 10, 30, 50); writeToLocal("C:\\Users\\Pictures\\AAA" + System.currentTimeMillis() + ".pdf", stream); } private static void writeToLocal(String destination, InputStream input) throws IOException { int index; byte[] bytes = new byte[1024]; FileOutputStream downloadFile = new FileOutputStream(destination); while ((index = input.read(bytes)) != -1) { downloadFile.write(bytes, 0, index); downloadFile.flush(); } downloadFile.close(); input.close(); } public static void PdfWatermarkLocal(String inputFile, String outputFile, String waterMarkName) { try { // 切记这里的参数是文件的路径 ，路径必须是双斜杠的如F:\\test.pdf，不能是F:/test.pdf 或者F:\test.pdf PdfReader reader = new PdfReader(inputFile); PdfStamper stamper = new PdfStamper(reader, Files.newOutputStream(Paths.get(outputFile))); BaseFont base = BaseFont.createFont("STSong-Light", "UniGB-UCS2-H", BaseFont.EMBEDDED); PdfGState gs = new PdfGState(); gs.setFillOpacity(0.2f);//改透明度 gs.setStrokeOpacity(0.4f); int total = reader.getNumberOfPages() + 1; JLabel label = new JLabel(); label.setText(waterMarkName); PdfContentByte under; // 可添加多个水印 Rectangle pageRect = null; label.setText(waterMarkName); for (int i = 1; i < total; i++) { pageRect = reader.getPageSizeWithRotation(i); int width1 = (int) pageRect.getWidth(); int height1 = (int) pageRect.getHeight(); int fontSize = (width1 + height1) / 80; // 间隔距离（参数可调节） int interval = fontSize * 2; // 文字占用的宽度 int xWidth = getStrWidth(waterMarkName, fontSize); // x,y可以绘制的数量,多加一个补充空白 int xCanNum = width1 / xWidth + 1; int yCanNum = height1 / fontSize + 1; // 在内容上方加水印 under = stamper.getOverContent(i); // 在内容下方加水印 //under = stamper.getUnderContent(i); under.saveState(); under.setGState(gs); under.beginText(); //水印字体和大小 under.setFontAndSize(base, fontSize); // 水印文字成30度角倾斜 for (int ii = 1; ii <= yCanNum; ii++) { int y = fontSize * ii + interval * ii; for (int jj = 0; jj < xCanNum; jj++) { int x = xWidth * jj + interval * jj; under.showTextAligned(Element.ALIGN_LEFT , waterMarkName, x, y - (fontSize + interval) * jj, 30); } } // 添加水印文字 under.endText(); } stamper.close(); reader.close(); } catch (Exception e) { e.printStackTrace(); } } public static OutputStream PdfWatermarkOut(InputStream inputStream, String waterMarkName) { try { PdfReader reader = new PdfReader(inputStream); ByteArrayOutputStream outputStream = new ByteArrayOutputStream(); PdfStamper stamper = new PdfStamper(reader, outputStream); BaseFont base = BaseFont.createFont("STSong-Light", "UniGB-UCS2-H", BaseFont.EMBEDDED); PdfGState gs = new PdfGState(); gs.setFillOpacity(0.2f);//改透明度 gs.setStrokeOpacity(0.4f); int total = reader.getNumberOfPages() + 1; JLabel label = new JLabel(); label.setText(waterMarkName); PdfContentByte under; // 可添加多个水印 Rectangle pageRect = null; label.setText(waterMarkName); for (int i = 1; i < total; i++) { pageRect = reader.getPageSizeWithRotation(i); int width1 = (int) pageRect.getWidth(); int height1 = (int) pageRect.getHeight(); int fontSize = (width1 + height1) / 80; // 间隔距离（参数可调节） int interval = fontSize * 2; // 文字占用的宽度 int xWidth = getStrWidth(waterMarkName, fontSize); // x,y可以绘制的数量,多加一个补充空白 int xCanNum = width1 / xWidth + 1; int yCanNum = height1 / fontSize + 1; // 在内容上方加水印 under = stamper.getOverContent(i); // 在内容下方加水印 //under = stamper.getUnderContent(i); under.saveState(); under.setGState(gs); under.beginText(); //水印字体和大小 under.setFontAndSize(base, fontSize); // 水印文字成30度角倾斜 for (int ii = 1; ii <= yCanNum; ii++) { int y = fontSize * ii + interval * ii; for (int jj = 0; jj < xCanNum; jj++) { int x = xWidth * jj + interval * jj; under.showTextAligned(Element.ALIGN_LEFT , waterMarkName, x, y - (fontSize + interval) * jj, 30); } } // 添加水印文字 under.endText(); } stamper.close(); reader.close(); return outputStream; } catch (Exception e) { throw new RuntimeException(e); } } public static InputStream PdfWatermarkInt(InputStream inputStream, String waterMarkName) { try { PdfReader reader = new PdfReader(inputStream); ByteArrayOutputStream outputStream = new ByteArrayOutputStream(); PdfStamper stamper = new PdfStamper(reader, outputStream); BaseFont base = BaseFont.createFont("STSong-Light", "UniGB-UCS2-H", BaseFont.EMBEDDED); PdfGState gs = new PdfGState(); gs.setFillOpacity(0.2f);//改透明度 gs.setStrokeOpacity(0.4f); int total = reader.getNumberOfPages() + 1; JLabel label = new JLabel(); label.setText(waterMarkName); PdfContentByte under; // 可添加多个水印 Rectangle pageRect = null; label.setText(waterMarkName); for (int i = 1; i < total; i++) { pageRect = reader.getPageSizeWithRotation(i); int width1 = (int) pageRect.getWidth(); int height1 = (int) pageRect.getHeight(); int fontSize = (width1 + height1) / 80; // 间隔距离（参数可调节） int interval = fontSize * 2; // 文字占用的宽度 int xWidth = getStrWidth(waterMarkName, fontSize); // x,y可以绘制的数量,多加一个补充空白 int xCanNum = width1 / xWidth + 1; int yCanNum = height1 / fontSize + 1; // 在内容上方加水印 under = stamper.getOverContent(i); // 在内容下方加水印 //under = stamper.getUnderContent(i); under.saveState(); under.setGState(gs); under.beginText(); //水印字体和大小 under.setFontAndSize(base, fontSize); // 水印文字成30度角倾斜 for (int ii = 1; ii <= yCanNum; ii++) { int y = fontSize * ii + interval * ii; for (int jj = 0; jj < xCanNum; jj++) { int x = xWidth * jj + interval * jj; under.showTextAligned(Element.ALIGN_LEFT , waterMarkName, x, y - (fontSize + interval) * jj, 30); } } // 添加水印文字 under.endText(); } stamper.close(); reader.close(); return new ByteArrayInputStream(outputStream.toByteArray()); } catch (Exception e) { throw new RuntimeException(e); } } public static int getStrWidth(String str, int fontSize) { char[] chars = str.toCharArray(); int fontSize2 = fontSize / 2; int width = 0; for (char c : chars) { int len = String.valueOf(c).getBytes().length; // 汉字为3,其余1 // 可能还有一些特殊字符占用2等等,统统计为汉字 if (len != 1) { width += fontSize; } else { width += fontSize2; } } return width == 0 ? 1 : width; }}水印工具类（写死文字大小个数）
import cn.hutool.core.date.DateUtil;import com.itextpdf.text.Element;import com.itextpdf.text.Rectangle;import com.itextpdf.text.pdf.*;import javax.swing.*;import java.awt.*;import java.io.*;import java.net.URL;import java.nio.file.Files;import java.nio.file.Paths;import static com.shinkeer.common.utils.SecurityUtils.getUsername;public class PdfWatermarkUtil { public static void main(String[] args) { PdfWatermarkLocal("D:\\AAA.pdf", "D:\\BBB.pdf", "这是水印"); } public static void main2(String[] args) throws Exception { File file = new File("D:\\AAA.pdf"); InputStream inputStream = file.toURL().openStream(); InputStream stream = PdfWatermarkTool.addPdfWatermark(inputStream, "这是水印" + DateUtil.now(), 10, 30, 50); writeToLocal("D:\\AAA" + System.currentTimeMillis() + ".pdf", stream); } private static void writeToLocal(String destination, InputStream input) throws IOException { int index; byte[] bytes = new byte[1024]; FileOutputStream downloadFile = new FileOutputStream(destination); while ((index = input.read(bytes)) != -1) { downloadFile.write(bytes, 0, index); downloadFile.flush(); } downloadFile.close(); input.close(); } public static void PdfWatermarkLocal(String inputFile, String outputFile, String waterMarkName) { try { // 水印的高和宽（参数可调节） int textH = 75; int textW = 170; // 间隔距离（参数可调节） int interval = 30; // 切记这里的参数是文件的路径 ，路径必须是双斜杠的如F:\\test.pdf，不能是F:/test.pdf 或者F:\test.pdf PdfReader reader = new PdfReader(inputFile); PdfStamper stamper = new PdfStamper(reader, Files.newOutputStream(Paths.get(outputFile))); BaseFont base = BaseFont.createFont("STSong-Light", "UniGB-UCS2-H", BaseFont.EMBEDDED); PdfGState gs = new PdfGState(); gs.setFillOpacity(0.2f);//改透明度 gs.setStrokeOpacity(0.4f); int total = reader.getNumberOfPages() + 1; JLabel label = new JLabel(); label.setText(waterMarkName); PdfContentByte under; // 可添加多个水印 Rectangle pageRect = null; FontMetrics metrics; label.setText(waterMarkName); metrics = label.getFontMetrics(label.getFont()); for (int i = 1; i < total; i++) { pageRect = reader.getPageSizeWithRotation(i); // 在内容上方加水印 under = stamper.getOverContent(i); // 在内容下方加水印 //under = stamper.getUnderContent(i); under.saveState(); under.setGState(gs); under.beginText(); under.setFontAndSize(base, 20); // 水印文字成30度角倾斜 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); } } // 添加水印文字 under.endText(); } stamper.close(); reader.close(); } catch (Exception e) { e.printStackTrace(); } } public static OutputStream PdfWatermarkOut(InputStream inputStream, String waterMarkName) { try { // 水印的高和宽（参数可调节） int textH = 75; int textW = 170; // 间隔距离（参数可调节） int interval = 30; PdfReader reader = new PdfReader(inputStream); ByteArrayOutputStream outputStream = new ByteArrayOutputStream(); PdfStamper stamper = new PdfStamper(reader, outputStream); BaseFont base = BaseFont.createFont("STSong-Light", "UniGB-UCS2-H", BaseFont.EMBEDDED); PdfGState gs = new PdfGState(); gs.setFillOpacity(0.2f);//改透明度 gs.setStrokeOpacity(0.4f); int total = reader.getNumberOfPages() + 1; JLabel label = new JLabel(); label.setText(waterMarkName); PdfContentByte under; // 可添加多个水印 Rectangle pageRect = null; FontMetrics metrics; label.setText(waterMarkName); metrics = label.getFontMetrics(label.getFont()); for (int i = 1; i < total; i++) { pageRect = reader.getPageSizeWithRotation(i); // 在内容上方加水印 under = stamper.getOverContent(i); // 在内容下方加水印 //under = stamper.getUnderContent(i); under.saveState(); under.setGState(gs); under.beginText(); under.setFontAndSize(base, 20); // 水印文字成30度角倾斜 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); } } // 添加水印文字 under.endText(); } stamper.close(); reader.close(); return outputStream; } catch (Exception e) { throw new RuntimeException(e); } } public static InputStream PdfWatermarkInt(InputStream inputStream, String waterMarkName) { try { // 水印的高和宽（参数可调节） int textH = 75; int textW = 170; // 间隔距离（参数可调节） int interval = 30; PdfReader reader = new PdfReader(inputStream); ByteArrayOutputStream outputStream = new ByteArrayOutputStream(); PdfStamper stamper = new PdfStamper(reader, outputStream); BaseFont base = BaseFont.createFont("STSong-Light", "UniGB-UCS2-H", BaseFont.EMBEDDED); PdfGState gs = new PdfGState(); gs.setFillOpacity(0.2f);//改透明度 gs.setStrokeOpacity(0.4f); int total = reader.getNumberOfPages() + 1; JLabel label = new JLabel(); label.setText(waterMarkName); PdfContentByte under; // 可添加多个水印 Rectangle pageRect = null; FontMetrics metrics; label.setText(waterMarkName); metrics = label.getFontMetrics(label.getFont()); for (int i = 1; i < total; i++) { pageRect = reader.getPageSizeWithRotation(i); // 在内容上方加水印 under = stamper.getOverContent(i); // 在内容下方加水印 //under = stamper.getUnderContent(i); under.saveState(); under.setGState(gs); under.beginText(); under.setFontAndSize(base, 20); // 水印文字成30度角倾斜 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); } } // 添加水印文字 under.endText(); } stamper.close(); reader.close(); return new ByteArrayInputStream(outputStream.toByteArray()); } catch (Exception e) { throw new RuntimeException(e); } }}来源地址：https://blog.csdn.net/Ying_ph/article/details/131800711
