java使用itext库创建pdf并生成目录

使用iText库可以方便地创建PDF文档并生成目录。

首先需要导入iText库，可以通过Maven或Gradle方式导入。

接着可以创建一个PdfDocument对象，并设置文档属性：

PdfDocument pdfDoc = new PdfDocument(new PdfWriter("output.pdf"));
Document document = new Document(pdfDoc);
pdfDoc.setTagged();
pdfDoc.getCatalog().setLang(new PdfString("en-us"));
pdfDoc.getCatalog().setViewerPreferences(new PdfViewerPreferences().setDisplayDocTitle(true));
document.setProperty(Property.SPLIT_CHARACTERS, new DefaultSplitCharacters() {
    @Override
    public boolean isSplitCharacter(GlyphLine text, int glyphPos) {
        return false;
    }
});

然后可以添加章节标题和内容：

// 添加章节标题
Paragraph chapterTitle = new Paragraph("Chapter 1").setFont(PdfFontFactory.createFont(FontConstants.HELVETICA_BOLD)).setFontSize(16);
Chapter chapter = new Chapter(chapterTitle, 1);
document.add(chapter);

// 添加章节内容
Paragraph para1 = new Paragraph("This is the first paragraph.");
Paragraph para2 = new Paragraph("This is the second paragraph.");
document.add(para1);
document.add(para2);

最后可以生成目录：

pdfDoc.addEventHandler(PdfDocumentEvent.START_PAGE, new IEventHandler() {
    @Override
    public void handleEvent(Event event) {
        try {
            PdfDocumentEvent docEvent = (PdfDocumentEvent) event;
            PdfPage page = docEvent.getPage();
            PdfCanvas canvas = new PdfCanvas(page.newContentStreamBefore(), page.getResources(), pdfDoc);
            Rectangle rect = new Rectangle(36, 750, 523, 36);
            Canvas canvas1 = new Canvas(canvas, pdfDoc, rect);
            Paragraph p = new Paragraph().add("Table of Contents").setFont(PdfFontFactory.createFont(FontConstants.HELVETICA_BOLD)).setFontSize(12);
            canvas1.add(p);
            canvas1.close();

            PdfOutline root = pdfDoc.getOutlines(false);
            for (int i = 1; i <= 3; i++) {
                PdfOutline chapterOutline = root.addOutline(String.format("Chapter %d", i));
                chapterOutline.addDestination(PdfDestination.makeDestination(new PdfString(String.format("chapter_%d", i))));
            }
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }
});

完整的代码示例可参考：

import com.itextpdf.kernel.colors.ColorConstants;
import com.itextpdf.kernel.font.PdfFont;
import com.itextpdf.kernel.font.PdfFontFactory;
import com.itextpdf.kernel.geom.Rectangle;
import com.itextpdf.kernel.pdf.*;
import com.itextpdf.layout.Document;
import com.itextpdf.layout.element.AreaBreak;
import com.itextpdf.layout.element.Chapter;
import com.itextpdf.layout.element.Paragraph;
import com.itextpdf.layout.element.Text;
import com.itextpdf.layout.property.AreaBreakType;
import com.itextpdf.layout.property.Property;
import com.itextpdf.layout.renderer.DocumentRenderer;
import com.itextpdf.layout.renderer.DrawContext;
import com.itextpdf.layout.renderer.IRenderer;
import com.itextpdf.layout.renderer.ParagraphRenderer;
import com.itextpdf.layout.splitting.DefaultSplitCharacters;
import com.itextpdf.layout.splitting.GlyphLine;
import com.itextpdf.layout.splitting.ISplitCharacters;
import com.itextpdf.layout.splitting.SplitCharacters;
import com.itextpdf.layout.splitting.SplitCharacters.DefaultSplitCharacter;
import com.itextpdf.layout.splitting.SplitCharacters.SplitCharacter;

import java.io.IOException;

public class PdfGenerator {
    public static void main(String[] args) throws IOException {
        PdfDocument pdfDoc = new PdfDocument(new PdfWriter("output.pdf"));
        Document document = new Document(pdfDoc);
        pdfDoc.setTagged();
        pdfDoc.getCatalog().setLang(new PdfString("en-us"));
        pdfDoc.getCatalog().setViewerPreferences(new PdfViewerPreferences().setDisplayDocTitle(true));
        document.setProperty(Property.SPLIT_CHARACTERS, new DefaultSplitCharacters() {
            @Override
            public boolean isSplitCharacter(GlyphLine text, int glyphPos) {
                return false;
            }
        });

        // 添加章节
        Paragraph chapterTitle = new Paragraph("Chapter 1").setFont(PdfFontFactory.createFont(FontConstants.HELVETICA_BOLD)).setFontSize(16);
        Chapter chapter = new Chapter(chapterTitle, 1);
        chapter.setDestination("chapter_1");
        document.add(chapter);

        Paragraph para1 = new Paragraph("This is the first paragraph.");
        Paragraph para2 = new Paragraph("This is the second paragraph.");
        document.add(para1);
        document.add(para2);

        document.add(new AreaBreak(AreaBreakType.NEXT_PAGE));

        chapterTitle = new Paragraph("Chapter 2").setFont(PdfFontFactory.createFont(FontConstants.HELVETICA_BOLD)).setFontSize(16);
        chapter = new Chapter(chapterTitle, 2);
        chapter.setDestination("chapter_2");
        document.add(chapter);

        para1 = new Paragraph("This is the third paragraph.");
        para2 = new Paragraph("This is the fourth paragraph.");
        document.add(para1);
        document.add(para2);

        document.add(new AreaBreak(AreaBreakType.NEXT_PAGE));

        chapterTitle = new Paragraph("Chapter 3").setFont(PdfFontFactory.createFont(FontConstants.HELVETICA_BOLD)).setFontSize(16);
        chapter = new Chapter(chapterTitle, 3);
        chapter.setDestination("chapter_3");
        document.add(chapter);

        para1 = new Paragraph("This is the fifth paragraph.");
        para2 = new Paragraph("This is the sixth paragraph.");
        document.add(para1);
        document.add(para2);

        // 添加目录
        pdfDoc.addEventHandler(PdfDocumentEvent.START_PAGE, new IEventHandler() {
            @Override
            public void handleEvent(Event event) {
                try {
                    PdfDocumentEvent docEvent = (PdfDocumentEvent) event;
                    PdfPage page = docEvent.getPage();
                    PdfCanvas canvas = new PdfCanvas(page.newContentStreamBefore(), page.getResources(), pdfDoc);
                    Rectangle rect = new Rectangle(36, 750, 523, 36);
                    Canvas canvas1 = new Canvas(canvas, pdfDoc, rect);
                    Paragraph p = new Paragraph().add("Table of Contents").setFont(PdfFontFactory.createFont(FontConstants.HELVETICA_BOLD)).setFontSize(12);
                    canvas1.add(p);
                    canvas1.close();

                    PdfOutline root = pdfDoc.getOutlines(false);
                    for (int i = 1; i <= 3; i++) {
                        PdfOutline chapterOutline = root.addOutline(String.format("Chapter %d", i));
                        chapterOutline.addDestination(PdfDestination.makeDestination(new PdfString(String.format("chapter_%d", i))));
                    }
                } catch (Exception ex) {
                    ex.printStackTrace();
                }
            }
        });

        document.close();
    }
}

在运行代码后，将会生成一个名为"output.pdf"的PDF文档，包含了三个章节和一个目录。