如何添加"Y的第X页" iText 7中的页脚 [英] How to add a "Page X of Y" footer in iText 7

问题描述

我试图弄清楚如何在使用 iText 7 生成的PDF文档的每个页面中添加"Y的X页"页脚.

I'm trying to figure out how to add a "Page X of Y" footer to each page in a PDF document, which I'm generating using iText 7.

使用IEventHandler生成"Page X"部分似乎很简单-这是我一直在努力的"of of Y"位.我想避免生成整个文档两次，以查明它有多少页，因为这会严重影响性能！

Using an IEventHandler to generate the "Page X" part seems fairly straightforward - it's the "of Y" bit that I'm struggling with. I want to avoid generating the whole document twice in order to find out how many pages it has, as this would be a significant performance hit!

我在以下 iText 5 中找到了解决方案:

I've found a solution for this in iText 5 here: PDF Page Numbering in Java & iText, but iText 7 is a complete rewrite of iText with a totally different interface and so far I've been unable to find any similar iText 7 examples.

推荐答案

回答您为iText 5 找到的内容引用了 MovieCountries1 示例.对于iText 7，此示例已重写为

The answer you found for iText 5 references the MovieCountries1 example. This example has been rewritten for iText 7 as Listing_05_20_MovieCountries1. Its pivotal code:

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(FontConstants.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;
    }
}

您还将在这里找到许多其他示例的重写.

You'll find rewrites of many other samples there, too.

正如@Bruno在评论中指出的，甚至还有一个稍稍不同的示例，该示例是为iText 7真正创建的(与上面的示例是iText 5示例的端口相反).

As @Bruno remarked in a comment, there even is a slightly different example which has been genuinely created for iText 7 (in contrast to the example above which is the port of an iText 5 example).

这是第7章"rel =" noreferrer> iText 7 :积木教程.它使用showTextAligned()确保"X的第X页"与"Y"很好地匹配，而不管X和Y有多少个数字，请参见.其页面结束事件监听器方法:

It's an example accompanying the chapter 7 of the iText 7: building blocks tutorial. It uses showTextAligned() to make sure the "Page X of" nicely matches with the "Y", no matter how many digits X and Y have, cf. its end-of-page event listener method:

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();
}

( C07E03_PageXofY.java ，事件处理程序类PageXofY)

(C07E03_PageXofY.java, event handler class PageXofY)

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