使用iText

Question

我在报告页脚中有一个HTML代码。但是，此页脚的高度可能会根据我的HTML代码的内容而有所不同。是否可以做一些工作来根据代码的大小自动调整页脚的高度？

Footer.java

public class Footer extends PdfPageEventHelper {
    protected ElementList footer;
    public Footer(String html) throws IOException {
        footer = XMLWorkerHelper.parseToElementList(html, null);
    }
    @Override
    public void onEndPage(PdfWriter writer, Document document) {
        try {
            ColumnText ct = new ColumnText(writer.getDirectContent());

            // In my case this rectagle is resizeable height
            ct.setSimpleColumn(new Rectangle(36, 200, 559, 32));

            for (Element e : footer) {
                ct.addElement(e);
            }
            ct.go();
        } catch (DocumentException de) {
            throw new ExceptionConverter(de);
        }
    }
}

Answer 1

您的页脚似乎没有任何动态部分，各页之间有所不同。在这种情况下，您可以简单地从将html渲染为一些一次性PDF并测量其尺寸开始，然后使用这些尺寸设置您创建的实际文档的边距。

您可以实施此方法，例如使用这样的页面事件侦听器类：

Movie.java
    @OneToMany(mappedBy = "movie", targetEntity = Clip.class, cascade = CascadeType.ALL, fetch = FetchType.EAGER)
    private Set<Clip> clips = new HashSet<Clip>();

//the below getter will look for data of related Clip
    public Set<Clip> getClips(){ return this.clips}


 Clip.java

    @ManyToOne
        @JoinColumn(name="movie_id")
        private Movie movie;

//the below getter will look for related Movie again
   public Movie getMovie() { return this.movie }

（StaticFooter助手类）

您可以这样应用它：

public static class Footer extends PdfPageEventHelper {
    private final Rectangle boundingBox;
    private final List<Element> elements;
    private PdfTemplate template = null;
    private float blankAfter = 0;

    public Footer(String html, float width) throws DocumentException, IOException {
        this(XMLWorkerHelper.parseToElementList(html, null), width);
    }

    public Footer(List<Element> elements, float width) throws DocumentException, IOException {
        this.elements = elements;
        try (   OutputStream os = new NullOutputStream()    ) {
            Document document = new Document();
            PdfWriter writer = PdfWriter.getInstance(document, os);
            document.open();

            Rectangle bbox = new Rectangle(0, 0, width, 1000);
            float bottomLine = createTemplate(writer, bbox);
            boundingBox = new Rectangle(width, bbox.getTop() - bottomLine);
            template = null;

            writer.setPageEmpty(false);
            document.close();
        }
    }

    float createTemplate(PdfWriter writer, Rectangle boundingBox) throws DocumentException {
        template = writer.getDirectContent().createTemplate(10000, 10000);
        template.setBoundingBox(boundingBox);
        ColumnText columnText = new ColumnText(template);
        Rectangle bbox = template.getBoundingBox();
        columnText.setSimpleColumn(bbox.getLeft(), bbox.getBottom(), bbox.getRight(), bbox.getTop());
        for (Element element : elements) {
            columnText.addElement(element);
        }
        columnText.go();
        return columnText.getYLine() + columnText.getDescender();
    }

    void ensureTemplate(PdfWriter writer) throws DocumentException {
        if (template == null) {
            createTemplate(writer, boundingBox);
        }
    }

    public void setBottomMargin(Document document, float blankBefore, float blankAfter) {
        float marginBottom = boundingBox.getHeight() + blankBefore + blankAfter;
        document.setMargins(document.leftMargin(), document.rightMargin(), document.topMargin(), marginBottom);
        this.blankAfter = blankAfter;
    }

    @Override
    public void onEndPage(PdfWriter writer, Document document) {
        try {
            ensureTemplate(writer);

            Rectangle bbox = template.getBoundingBox();
            Rectangle pageSize = document.getPageSize();

            float x = pageSize.getLeft((pageSize.getWidth() - bbox.getWidth()) / 2f - bbox.getLeft());
            float y = pageSize.getBottom(blankAfter - bbox.getBottom());
            writer.getDirectContentUnder().addTemplate(template, x, y);
        } catch (DocumentException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        super.onEndPage(writer, document);
    }
}

（StaticFooter测试Document document = new Document(); PdfWriter writer = PdfWriter.getInstance(document, new FileOutputStream(new File(RESULT_FOLDER, "StaticFooterShort.pdf"))); String html = "<p>Short Test Footer.</p>"; Footer footer = new Footer(html, document.right() - document.left()); writer.setPageEvent(footer); footer.setBottomMargin(document, 10, 10); document.open(); for (int i = 0; i < 200; i++) { document.add(new Paragraph("Lorem ipsum dolor sit amet, consetetur sadipscing elitr, ...")); } document.close(); ）

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PS：我使用的testShortFooter类是Apache Commons IO帮助器，但是如果您不希望额外的依赖关系，可以轻松实现类似的东西，只需实现忽略所有输入的NullOutputStream即可。