xhtmlrenderer创建长度为0的PDF [英] xhtmlrenderer creating PDFs of length 0

问题描述

我是 org.xhtmlrenderer.pdf.ITextRenderer 的新手，并遇到此问题：

I am new to org.xhtmlrenderer.pdf.ITextRenderer and have this problem:

PDF我的测试servlet流到我的下载文件夹实际上是空文件。

The PDFs that my test servlet streams to my Downloads folder are in fact empty files.

相关方法 streamAndDeleteTheClob 如下所示。

第一个尝试块肯定不是问题。

The first try block is definitely not a problem.

服务器在第二个尝试块中花费了大量时间。没有异常抛出。

The server spends a lot of time in the second try block. No exception thrown.

任何人都可以建议解决这个问题或者调试它的好方法吗？

Can anyone suggest a solution to this problem or a good approach to to debugging it?

有人能指出基本相似的代码吗？

Can anyone point me to essentially similar code that really works?

任何帮助都会非常感激。

Any help would be much appreciated.

res.setContentType("application/pdf");

ServletOutputStream out = res.getOutputStream();

...

private boolean streamAndDeleteTheClob(int pageid,
                                  Connection con,
                                  ServletOutputStream out) throws IOException, ServletException {
   Statement statement;

   Clob htmlpage;

   StringBuffer pdfbuf = new StringBuffer();

   final String pageToSendQuery = "SELECT text FROM page WHERE pageid = " + pageid;

   // create xhtml file as a CLOB (Oracle large character object) and stream it into StringBuffer pdfbuf

  try {  // definitely no problem in this block
    statement = con.createStatement();
    resultSet = statement.executeQuery(pageToSendQuery);
    if (resultSet.next()) {
      htmlpage = resultSet.getClob(1);
    } else {
      return true;
    }
    final Reader in = htmlpage.getCharacterStream();
    final char[] buffer = new char[4096];
    while ((in.read(buffer)) != -1) {
      pdfbuf.append(buffer);
    }            
  } catch (Exception ex) {       
    out.println("buffering CLOB failed: " + ex);
  }

  // create pdf from StringBuffer

  try {
    DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
    Document doc = builder.parse(new InputSource(new StringReader(pdfbuf.toString())));
    ITextRenderer renderer = new ITextRenderer();
    renderer.setDocument(doc, null);
    renderer.layout();
    renderer.createPDF(out);
    out.close();
  } catch (Exception ex) {
    out.println("streaming of pdf failed: " + ex);

  }

  deleteClob(con, pageid);

  return false;
}

推荐答案

使用DocumentBuilder.parse方法将尝试解析XHTML页面中引用的DTD。这需要很长时间。如果您使用Flying Saucer（xhtmlrenderer），最简单的方法是以这种方式创建文档：

Using the DocumentBuilder.parse this way will try to resolve the DTD referenced in the XHTML page. It takes a really long time. The easyest way to aviod that if you are using the Flying Saucer (xhtmlrenderer), is to create the document this way:

Document myDocument = XMLResource.load(myInputStream).getDocument();

请注意，您也可以将XMLResource.load与Reader一起使用。

Note that you can use XMLResource.load with a Reader too.

这篇关于xhtmlrenderer创建长度为0的PDF的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！