如何将HTML页眉和页脚添加到页面？

如何使用itext从html源添加标题到pdf？

目前，我们已经扩展了PdfPageEventHelper并覆盖了这些方法。 工作正常，但当我到2页以上时它会抛出RuntimeWorkerException。

@Override void onStartPage(PdfWriter writer, Document document) { InputStream is = new ByteArrayInputStream(header?.getBytes()); XMLWorkerHelper.getInstance().parseXHtml(writer, document, is); } @Override void onEndPage(PdfWriter writer, Document document) { InputStream is = new ByteArrayInputStream(footer?.getBytes()); XMLWorkerHelper.getInstance().parseXHtml(writer, document, is); } 

Answer 1

一般来说， 禁止在onStartPage()事件中添加内容。 禁止在onEndPage()向document对象添加内容。 您应该使用PdfWriter ， NOT文档在onEndPage()方法中添加页眉和页脚。 另外：通过一遍又一遍地解析HTML，你浪费了大量的CPU。

请看一下HtmlHeaderFooter示例。

它有两个HTML代码段，一个用于页眉，一个用于页脚。

 public static final String HEADER = "
Header
Some title
"; public static final String FOOTER = "
Footer
Some title
"; 

请注意，有更好的方法来描述页眉和页脚，而不是使用HTML，但也许这是你的要求之一，所以我不会问你为什么不使用官方文档中解释的任何方法。 顺便说一下：您可以在免费电子书中找到解决问题所需的所有信息，以便下载它…

我们只会在页面事件中阅读这些HTML代码段，然后我们将在每个页面上反复渲染元素：

 public class HeaderFooter extends PdfPageEventHelper { protected ElementList header; protected ElementList footer; public HeaderFooter() throws IOException { header = XMLWorkerHelper.parseToElementList(HEADER, null); footer = XMLWorkerHelper.parseToElementList(FOOTER, null); } @Override public void onEndPage(PdfWriter writer, Document document) { try { ColumnText ct = new ColumnText(writer.getDirectContent()); ct.setSimpleColumn(new Rectangle(36, 832, 559, 810)); for (Element e : header) { ct.addElement(e); } ct.go(); ct.setSimpleColumn(new Rectangle(36, 10, 559, 32)); for (Element e : footer) { ct.addElement(e); } ct.go(); } catch (DocumentException de) { throw new ExceptionConverter(de); } } } 

您是否看到我们用于添加从XML Worker获取的Element对象的机制？ 我们创建一个ColumnText对象，该对象将写入编写器的直接内容 （禁止使用该document ）。 我们定义一个Rectangle ，我们使用go()来渲染元素。

结果显示在html_header_footer.pdf中 。

Answer 2

Bruno的anwser是正确的，但它完全不适合我，因为XMLWorkerHelper.parsetoElementsList无法解析某些系统字体另一方面XMLWorkerHelper.getInstance（）。parseXHtml（writer，document，is）; 我能够正确地解析系统字体，所以我必须沿着元素处理程序的路线走下去，这里有一个处理方式，这是C＃中的代码

  /// 
 /// returns pdf in bytes. /// 
 /// contents. /// header contents. /// footer contents. ///  public Byte[] GetPDF(string contentsHtml, string headerHtml, string footerHtml) { // Create a byte array that will eventually hold our final PDF Byte[] bytes; // Boilerplate iTextSharp setup here // Create a stream that we can write to, in this case a MemoryStream using (var ms = new MemoryStream()) { // Create an iTextSharp Document which is an abstraction of a PDF but **NOT** a PDF using (var document = new Document(PageSize.A4, 40, 40, 120, 120)) { // Create a writer that's bound to our PDF abstraction and our stream using (var writer = PdfWriter.GetInstance(document, ms)) { // Open the document for writing document.Open(); var headerElements = new HtmlElementHandler(); var footerElements = new HtmlElementHandler(); XMLWorkerHelper.GetInstance().ParseXHtml(headerElements, new StringReader(headerHtml)); XMLWorkerHelper.GetInstance().ParseXHtml(footerElements, new StringReader(footerHtml)); writer.PageEvent = new HeaderFooter(headerElements.GetElements(), footerElements.GetElements()); // Read your html by database or file here and store it into finalHtml eg a string // XMLWorker also reads from a TextReader and not directly from a string using (var srHtml = new StringReader(contentsHtml)) { // Parse the HTML iTextSharp.tool.xml.XMLWorkerHelper.GetInstance().ParseXHtml(writer, document, srHtml); } document.Close(); } } // After all of the PDF "stuff" above is done and closed but **before** we // close the MemoryStream, grab all of the active bytes from the stream bytes = ms.ToArray(); } return bytes; } } 

页面事件和元素处理程序代码在这里

 public partial class HeaderFooter : PdfPageEventHelper { private ElementList HeaderElements { get; set; } private ElementList FooterElements { get; set; } public HeaderFooter(ElementList headerElements, ElementList footerElements) { HeaderElements = headerElements; FooterElements = footerElements; } public override void OnEndPage(PdfWriter writer, Document document) { base.OnEndPage(writer, document); try { ColumnText headerText = new ColumnText(writer.DirectContent); foreach (IElement e in HeaderElements) { headerText.AddElement(e); } headerText.SetSimpleColumn(document.Left, document.Top, document.Right, document.GetTop(-100), 10, Element.ALIGN_MIDDLE); headerText.Go(); ColumnText footerText = new ColumnText(writer.DirectContent); foreach (IElement e in FooterElements) { footerText.AddElement(e); } footerText.SetSimpleColumn(document.Left, document.GetBottom(-100), document.Right, document.GetBottom(-40), 10, Element.ALIGN_MIDDLE); footerText.Go(); } catch (DocumentException de) { throw new Exception(de.Message); } } } public class HtmlElementHandler : IElementHandler { public ElementList Elements { get; set; } public HtmlElementHandler() { Elements = new ElementList(); } public ElementList GetElements() { return Elements; } public void Add(IWritable w) { if (w is WritableElement) { foreach (IElement e in ((WritableElement)w).Elements()) { Elements.Add(e); } } } }