iText如何同时使用PdfWriterPipeline和PdfSmartCopy？

Question

我正在使用iText将 HTML 转换为 PDF 文件。我意识到输出文件大小太大，因此我决定使用它PdfSmartCopy来删除对象重复项。PdfSmartCopy我可以在 HTML 到 PDF 过程完成后使用，例如，我用来PdfSmartCopy从磁盘加载文件并将 PDF 转换为较小的尺寸。

我的问题是，我可以简化PdfSmartCopyHTML 到 PDF 的流程吗？我发现这PdfSmartCopy是 的子类PdfWriter。所以我将代码更改为：

public static void main(String[] args) throws Exception {

    try (OutputStream file = new FileOutputStream(new File("output.pdf"))) {

        Document document = new Document(PageSize.A4);

        //PdfWriter writer = PdfWriter.getInstance(document, file); // remove this line 

        PdfSmartCopy pdfCopy = new PdfSmartCopy(document, file); // change to this line

        pdfCopy.setInitialLeading(12.5f);

        document.open();

        CSSResolver cssResolver = new StyleAttrCSSResolver();

        CssFile cssFile = XMLWorkerHelper.getCSS(new FileInputStream("itext2\\css\\bootstrap.min.css"));

        cssResolver.addCss(cssFile);

        HtmlPipelineContext htmlContext = new HtmlPipelineContext(null);

        htmlContext.setTagFactory(Tags.getHtmlTagProcessorFactory());

        PdfWriterPipeline pdf = new PdfWriterPipeline(document, pdfCopy);

        HtmlPipeline html = new HtmlPipeline(htmlContext, pdf);

        CssResolverPipeline css = new CssResolverPipeline(cssResolver, html);

        XMLWorker worker = new XMLWorker(css, true);

        XMLParser p = new XMLParser(worker);

        String fileContent = PdfTest.readFile("itext2\\template.html");

        p.parse(new StringReader(fileContent));

        document.close();

        pdfCopy.close();

        file.close();

    } catch (Exception e) {

        e.printStackTrace();

    }

}

PdfSmartCopy是否可以在进行 HTML 到 PDF 渲染的同时使用？

https://api.itextpdf.com/iText5/5.5.9/com/itextpdf/text/pdf/PdfSmartCopy.html#PdfSmartCopy-com.itextpdf.text.Document-java.io.OutputStream-

Answer 1

在HTML到PDF的渲染过程中，我将其保存到内存中，稍后用于PdfSmartCopy生成slim pdf版本，这可以防止我在文件系统中生成两个不同的pdf文件（稍后无法删除）非纤薄的），如果对其他人有帮助，请粘贴以下代码：try (ByteArrayOutputStream byteData = new ByteArrayOutputStream()) {    Document document = new Document(PageSize.A4);    PdfWriter writer = PdfWriter.getInstance(document, byteData);               writer.setInitialLeading(12.5f);    document.open();    CSSResolver cssResolver = new StyleAttrCSSResolver();    CssFile cssFile = XMLWorkerHelper.getCSS(new FileInputStream("itext2\\css\\bootstrap.min.css"));    cssResolver.addCss(cssFile);    HtmlPipelineContext htmlContext = new HtmlPipelineContext(null);    htmlContext.setTagFactory(Tags.getHtmlTagProcessorFactory());    PdfWriterPipeline pdf = new PdfWriterPipeline(document, writer);    HtmlPipeline html = new HtmlPipeline(htmlContext, pdf);    CssResolverPipeline css = new CssResolverPipeline(cssResolver, html);    XMLWorker worker = new XMLWorker(css, true);    XMLParser p = new XMLParser(worker);    String fileContent = PdfTest.readFile("itext2\\template.html");    p.parse(new StringReader(fileContent));    document.close();    PdfReader reader = new PdfReader(byteData.toByteArray());    Document document1 = new Document();    File resultFile = new File("result.pdf");    PdfSmartCopy pdfCopy = new PdfSmartCopy(document1, new FileOutputStream(resultFile));    document1.open();    PdfImportedPage page;    for (int pageNumber = 1; pageNumber <= reader.getNumberOfPages(); pageNumber++) {        page = pdfCopy.getImportedPage(reader, pageNumber);        pdfCopy.addPage(page);    }    document1.close();    byteData.close();} catch (Exception e) {    e.printStackTrace();}