Question

I'm using iText to convert HTML file structure to PDF. My HTML files contain code snippets in <pre> blocks, but iText doesn't leave them formatted as they are.

Example of my <pre> block:

<something>
   <somethingelse>
      some content
   </somethingelse>
</something>

This is what iText outputs to PDF:

<something>  <somethingelse> some content  </somethingelse>  </something>

Is there a way to configure iText to format this correctly?

My iText code snippet:

FileOutputStream os = new FileOutputStream(...);
Document doc = new Document(PageSize.A4);
PdfWriter writer = PdfWriter.getInstance(doc, os);
CSSResolver cssResolver = XMLWorkerHelper.getInstance().getDefaultCssResolver(true);
HtmlPipelineContext htmlContext = new HtmlPipelineContext();

htmlContext.setTagFactory(Tags.getHtmlTagProcessorFactory());
htmlContext.setImageProvider(new AbstractImageProvider() {
    public String getImageRootPath() {
        ...
    }
});

Pipeline<?> pipeline = new CssResolverPipeline(cssResolver,
                       new HtmlPipeline(htmlContext,
                       new PdfWriterPipeline(doc, writer)));
XMLWorker worker = new XMLWorker(pipeline, true);
XMLParser parser = new XMLParser(worker);

doc.open();

for (String inputFile : inputFiles) {
    parser.parse(new FileInputStream(inputFile), StandardCharsets.UTF_8);
}

doc.close();

Answer 1

您可以实现自己的TagProcessor并在TagProcessorFactory上注册它：

[...]
HtmlPipelineContext htmlContext = new HtmlPipelineContext(null);

TagProcessorFactory tagFactory = Tags.getHtmlTagProcessorFactory();
tagFactory.addProcessor(new TagProcessor() {

    @Override
    public List<Element> startElement(WorkerContext ctx, Tag tag) {
        return null;
    }

    @Override
    public List<Element> content(WorkerContext ctx, Tag tag, String content) {
        return null;
    }

    @Override
    public List<Element> endElement(WorkerContext ctx, Tag tag, List<Element> currentContent) {
        return null;
    }

    @Override
    public boolean isStackOwner() {
        return false;
    }
}, "pre");

htmlContext.setTagFactory(tagFactory);
[...]

然后，您可以使用Tag对象创建iText元素并将其返回到List对象中。您如何格式化和处理内容完全取决于您。

Answer 2

以下代码段（基于您的代码段和XMLWorker Documentation）会创建一个包含<pre>块的PDF。

public class HtmlToPdf {

    // proper exception handling needs to be implemented
    public static void main(String[] args) throws Exception {
        Document document = new Document(PageSize.A4);
        PdfWriter pdfWriter = PdfWriter.getInstance(document,
                new FileOutputStream("r:/temp/testpdf.pdf")
        );

        CSSResolver cssResolver = XMLWorkerHelper.getInstance()
                .getDefaultCssResolver(true);
        HtmlPipelineContext htmlContext = new HtmlPipelineContext(null);

        htmlContext.setTagFactory(Tags.getHtmlTagProcessorFactory());

        Pipeline<?> pipeline = new CssResolverPipeline(cssResolver,
                new HtmlPipeline(htmlContext,
                        new PdfWriterPipeline(document, pdfWriter)
                )
        );
        XMLWorker worker = new XMLWorker(pipeline, true);
        XMLParser parser = new XMLParser(worker);

        document.open();

        String str = "<!DOCTYPE html PUBLIC \"-//W3C//DTD XHTML 1.0 Strict//EN\" \n"
                + "   \"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd\">\n"
                + "<html xmlns=\"http://www.w3.org/1999/xhtml\" lang=\"en\" xml:lang=\"en\">\n"
                + "  <head>\n"
                + "    <title>sample html</title>\n"
                + "  </head>\n"
                + "  <body>\n"
                + "    <h2>sample text</h2>\n"
                + "    <pre>\n"
                + "      &lt;something&gt;\n"
                + "        &lt;somethingelse&gt;\n"
                + "          some content\n"
                + "        &lt;/somethingelse&gt;\n"
                + "      &lt;/something&gt;\n"
                + "    </pre>\n"
                + "  </body>\n"
                + "</html>";
        parser.parse(new StringReader(str));
        document.close();
    }
}

Java iText HTML to PDF <pre> block formatting

2 个答案: