如何在iText 7中添加“Y的X页”页脚

Question

使用IEventHandler生成“Page X”部分似乎相当简单--我正在努力解决的是“Y”部分。我希望避免为了找出它有多少页而对整个文档生成两次，因为这将对性能产生重大影响！

我已经在iText5中找到了一个解决方案：Java中的PDF页码和iText，但是iText7是iText的完全重写，接口完全不同，到目前为止我还找不到任何类似的iText7示例。

Answer 1

您为iText5找到的答案引用了MovieCountries1示例。对于iText7，此示例被重写为清单0520MovieCountries1。它的关键代码：

protected PdfFont bold;
protected PdfFont italic;
protected PdfFont normal;

protected PdfFormXObject template;

public void manipulatePdf(String dest) throws IOException, SQLException {
    PdfDocument pdfDoc = new PdfDocument(new PdfWriter(dest));
    Document doc = new Document(pdfDoc, new PageSize(PageSize.A4), true);
    doc.setMargins(54, 36, 36, 36);

    bold = PdfFontFactory.createFont(FontConstants.HELVETICA_BOLD);
    italic = PdfFontFactory.createFont(FontConstants.HELVETICA_OBLIQUE);
    normal = PdfFontFactory.createFont(FontConstants.HELVETICA);

    template = new PdfFormXObject(new Rectangle(550, 803, 30, 30));
    PdfCanvas canvas = new PdfCanvas(template, pdfDoc);

    HeaderHandler headerHandler = new HeaderHandler();
    pdfDoc.addEventHandler(PdfDocumentEvent.START_PAGE, headerHandler);

    ... ADD CONTENT ...

    canvas.beginText();
    try {
        canvas.setFontAndSize(PdfFontFactory.createFont(FontConstants.HELVETICA), 12);
    } catch (IOException e) {
        e.printStackTrace();
    }
    canvas.moveText(550, 803);
    canvas.showText(Integer.toString(pdfDoc.getNumberOfPages()));
    canvas.endText();
    canvas.release();

    doc.close();
}

public class HeaderHandler implements IEventHandler {
    protected String country;

    @Override
    public void handleEvent(Event event) {
        PdfDocumentEvent docEvent = (PdfDocumentEvent) event;
        PdfPage page = docEvent.getPage();
        int pageNum = docEvent.getDocument().getPageNumber(page);
        PdfCanvas canvas = new PdfCanvas(page);
        canvas.beginText();
        try {
            canvas.setFontAndSize(PdfFontFactory.createFont(StandardFonts.HELVETICA), 12);
        } catch (IOException e) {
            e.printStackTrace();
        }
        canvas.moveText(34, 803);
        canvas.showText(country);
        canvas.moveText(450, 0);
        canvas.showText(String.format("Page %d of", pageNum));
        canvas.endText();
        canvas.stroke();
        canvas.addXObject(template, 0, 0);
        canvas.release();
    }

    public void setHeader(String country) {
        this.country = country;
    }
}

你也会在那里找到许多其他样本的重写。

正如@Bruno在评论中所说，甚至有一个稍微不同的例子，它是真正为iText7创建的（与上面的例子相反，这个例子是iText5例子的端口）。

public void handleEvent(Event event) {
    PdfDocumentEvent docEvent = (PdfDocumentEvent) event;
    PdfDocument pdf = docEvent.getDocument();
    PdfPage page = docEvent.getPage();
    int pageNumber = pdf.getPageNumber(page);
    Rectangle pageSize = page.getPageSize();
    PdfCanvas pdfCanvas = new PdfCanvas(
        page.newContentStreamBefore(), page.getResources(), pdf);
    Canvas canvas = new Canvas(pdfCanvas, pdf, pageSize);
    Paragraph p = new Paragraph()
        .add("Page ").add(String.valueOf(pageNumber)).add(" of");
    canvas.showTextAligned(p, x, y, TextAlignment.RIGHT);
    pdfCanvas.addXObject(placeholder, x + space, y - descent);
    pdfCanvas.release();
}