如何修复PDF转换时出现的XML无效字符（Unicode:0x13）错误

问题现象 #

转换含特殊字符的HTML到PDF时出现以下错误：

>>> Creation of PDF {} is invalid!
Can't load the XML resource (using TRaX transformer). org.xml.sax.SAXParseException; lineNumber: 20; columnNumber: 4615; An invalid XML character (Unicode: 0x13) was found in the element content of the document.
org.xml.sax.SAXParseException; lineNumber: 20; columnNumber: 4615; An invalid XML character (Unicode: 0x13) was found in the element content of the document.
An invalid XML character (Unicode: 0x13) was found in the element content of the document.

相关代码 #

public ByteArrayInputStream createPdf(String textToConvert) throws IOException {

    ByteArrayOutputStream out = new ByteArrayOutputStream();
    PDDocument document = new PDDocument();

    try {
        PdfRendererBuilder builder = new PdfRendererBuilder();
        builder.defaultTextDirection(BaseRendererBuilder.TextDirection.LTR);

        builder.withHtmlContent(textToConvert, "");

        PDFont font = PDType0Font.load(document, this.getClass().getClassLoader().getResourceAsStream("fonts/" + FontNameEnum.TT_NORMS_PRO_REGULAR.getName()));
        font.encode("UTF-8");
        PDFontSupplier fontSupplier = new PDFontSupplier(font);

        builder.useFont(fontSupplier, "TTNormsPro-Regular");
        builder.usePDDocument(document);

        PdfBoxRenderer renderer = builder.buildPdfRenderer();
        renderer.createPDFWithoutClosing();

        document.save(out);
    } catch (Exception e) {
       e.printStackTrace();
    } finally {
        document.close();
    }

    return new ByteArrayInputStream(out.toByteArray());
}

解决方案 #

使用\P{Print}会误删Ÿ、Ã、È这类合法UTF-8字符，正确做法是仅移除XML规范明确禁止的非法字符，保留所有合法字符。

步骤1：添加文本清理方法 #

实现方法过滤XML 1.0不允许的字符：

private String cleanXmlInvalidChars(String input) {
    // XML 1.0允许的字符范围：#x9 | #xA | #xD | [#x20-#xD7FF] | [#xE000-#xFFFD] | [#x10000-#x10FFFF]
    return input.replaceAll("[^\\x09\\x0A\\x0D\\x20-\\xD7FF\\xE000-\\xFFFD\\x10000-\\x10FFFF]", "");
}

步骤2：在PDF转换前清理文本 #

修改createPdf方法，传入HTML内容前先执行清理：

// 在builder.withHtmlContent前添加清理逻辑
String cleanedHtml = cleanXmlInvalidChars(textToConvert);
builder.withHtmlContent(cleanedHtml, "");

这样既能移除0x13这类XML非法字符，又能保留所有合法UTF-8字符，避免误删问题。

内容的提问来源于stack exchange，提问作者vikifor