Java實現PDF水印文字換行、平鋪、旋轉效果

Java代碼實現對PDF的水印文字的添加。
水印的效果是：水印文字的換行、水印文字的平鋪、水印文字的旋轉。

import java.awt.FontMetrics;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;

import javax.swing.JLabel;

import com.itextpdf.text.BaseColor;
import com.itextpdf.text.DocumentException;
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;

public class TestWaterPrint {

    public static void setWatermark(BufferedOutputStream bos, String input, String waterMarkContent)
            throws DocumentException, IOException {
        // 使用"||"將內容進行分割
        String[] waterMarkContents = waterMarkContent.split("\\|\\|");

        PdfReader reader = new PdfReader(input);
        PdfStamper stamper = new PdfStamper(reader, bos);

        // 獲取總頁數 +1, 下面從1開始遍歷
        int total = reader.getNumberOfPages() + 1;

        BaseFont base = BaseFont.createFont("STSong-Light", "UniGB-UCS2-H", BaseFont.EMBEDDED);

        // 間隔
        int interval = 20;
        // 獲取水印文字的最大高度和寬度
        int textH = 0, textW = 0;
        for (int j = 0; j < waterMarkContents.length; j++) {
            JLabel label = new JLabel();
            label.setText(waterMarkContents[j]);
            FontMetrics metrics = label.getFontMetrics(label.getFont());
            if (textH < metrics.getHeight()) {
                textH = metrics.getHeight();
            }
            if (textW < metrics.stringWidth(label.getText())) {
                textW = metrics.stringWidth(label.getText());
            }
        

        // 設置水印透明度
        PdfGState gs = new PdfGState();
        gs.setFillOpacity(0.4f);
        gs.setStrokeOpacity(0.4f);

        Rectangle pageSizeWithRotation = null;
        PdfContentByte content = null;
        for (int i = 1; i < total; i++) {
            content = stamper.getOverContent(i);
            content.saveState();
            content.setGState(gs);

            // 設置字體和字體大小
            content.beginText();
            content.setFontAndSize(base, 20);

            // 設置顏色
            content.setColorFill(BaseColor.RED);

            // 獲取每一頁的高度、寬度
            pageSizeWithRotation = reader.getPageSizeWithRotation(i);
            float pageHeight = pageSizeWithRotation.getHeight();
            float pageWidth = pageSizeWithRotation.getWidth();

            // 根據紙張大小多次添加， 水印文字成30度角傾斜
            for (int height = interval + textH; height < pageHeight; height = height + textH * 6) {
                for (int width = interval + textW; width < pageWidth + textW; width = width + textW * 2) {
                    // 將分段的字段進行輸出編寫
                    for (int z = 0; z < waterMarkContents.length; z++) {
                        content.showTextAligned(Element.ALIGN_LEFT, waterMarkContents[z], width - textW, height -(textH+10) * (z + 1), 30);
                    }
                }
            }

            content.endText();
        }

        // 關閉流
        stamper.close();
        reader.close();
    }

    public static void main(String[] args) throws DocumentException, IOException {
        // 輸出的pdf文件
        BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(new File("/Users/yangyun/Documents/personal_doc/pic/11.pdf")));
       
        setWatermark(bos, "/Users/yangyun/Documents/personal_doc/pic/2020_PDF.pdf", "CSDN||stepMore||2020-5-30 11:19:12");
    }
}

示例PDF文件

添加水印後的PDF文件