文件在线预览doc,docx转换pdf(一)

时间:2022-02-05 04:29:46

文件在线预览doc,docx转换pdf(一)

1. 前言

文档转换是一个是一块硬骨头,但是也是必不可少的,我们正好做的知识库产品中,也面临着同样的问题,文档转换,精准的全文搜索,知识的转换率,是知识库产品的基本要素,初识阅读时同时绞尽脑汁,自己开发?,集成第三方?都是中小企业面临的一大难题…….

自己在网上搜索着找到poi开源出来的很多例子,最开始是用poi把所有文档转换为html,

1) 在github上面找到一个https://github.com/litter-fish/transform完整的demo,你想要的转换基本都提供,初学者可以参照实现转换出来的基本样子,达到通用级别,需要自己花很多功夫。此开源代码是基于poi和itext(pdf)的转换方式。

2) https://gitee.com/kekingcn/file-online-preview这是开源中国提供的一个源码,基于jodconverter,原理是调用windows,另存为的组件,实现转换。

3) 收费产品例如【永中office】【office365】【idocv】、【https://downloads.aspose.com/words/java】





2. 转换思路

自己在尝试过很多后,也与永中集成了文档转换,发现,要想完成预览的品质,必须的做二次渲染。毕竟永中做了十几年文档转换我们不能比的,自己琢磨后,发现一个勉强靠谱的思路,doc和docx都转换为pdf实现预览。都是在基于poi的基础上。

2.1. Doc转换pdf

1) Doc转换为xml



/**
* doc转xml
*/
public String toXML(String filePath){ try{ POIFSFileSystem nPOIFSFileSystem = new POIFSFileSystem(new File(filePath)); HWPFDocument nHWPFDocument = new HWPFDocument(nPOIFSFileSystem);
WordToFoConverter nWordToHtmlConverter = new WordToFoConverter(
DocumentBuilderFactory.newInstance().newDocumentBuilder().newDocument());
PicturesManager nPicturesManager = new PicturesManager() { public String savePicture(byte[] arg0, PictureType arg1,String arg2, float arg3, float arg4) {
//file:///F://20.vscode//iWorkP//temp//images//0.jpg
//System.out.println("file:///"+PathMaster.getWebRootPath()+ java.io.File.separator + "temp"+java.io.File.separator+"images" + java.io.File.separator + arg2);
// return "file:///"+PathMaster.getWebRootPath()+java.io.File.separator +"temp"+java.io.File.separator+"images" + java.io.File.separator + arg2;
return "file:///"+PathMaster.getWebRootPath()+java.io.File.separator +"temp"+java.io.File.separator+"images" + java.io.File.separator + arg2;
}
}; nWordToHtmlConverter.setPicturesManager(nPicturesManager);
nWordToHtmlConverter.processDocument(nHWPFDocument);
String nTempPath = PathMaster.getWebRootPath() + java.io.File.separator + "temp" + java.io.File.separator + "images" + java.io.File.separator;
File nFile = new File(nTempPath); if (!nFile.exists()) {
nFile.mkdirs();
}
for (Picture nPicture : nHWPFDocument.getPicturesTable().getAllPictures()) {
nPicture.writeImageContent(new FileOutputStream(nTempPath + nPicture.suggestFullFileName()));
}
Document nHtmlDocument = nWordToHtmlConverter.getDocument();
OutputStream nByteArrayOutputStream = new FileOutputStream(OUTFILEFO);
DOMSource nDOMSource = new DOMSource(nHtmlDocument);
StreamResult nStreamResult = new StreamResult(nByteArrayOutputStream); TransformerFactory nTransformerFactory = TransformerFactory.newInstance();
Transformer nTransformer = nTransformerFactory.newTransformer(); nTransformer.setOutputProperty(OutputKeys.ENCODING, "GBK");
nTransformer.setOutputProperty(OutputKeys.INDENT, "YES");
nTransformer.setOutputProperty(OutputKeys.METHOD, "xml"); nTransformer.transform(nDOMSource, nStreamResult); nByteArrayOutputStream.close(); return ""; }catch(Exception e){
e.printStackTrace();
}
return "";
}

2) Xml转换为pdf

这里我是使用fop通过xml转换为pdf,也是最近欣喜的一个发现,poi官网推荐的我一直没去仔细看,里面的架包和永中的很多高清包,一模一样,现在貌似路子对了。有兴趣者研究去吧。我的源码已经在githubhttps://github.com/liuxufeijidian/file.convert.master/tree/master上面,环境已经配置好,需要准备好doc和docx文档即可。

/*
* xml 转pdf
*/
public void xmlToPDF() throws SAXException, TransformerException{
// Step 1: Construct a FopFactory by specifying a reference to the configuration file
// (reuse if you plan to render multiple documents!)
FopFactory fopFactory = null;
new URIResolverAdapter(new URIResolver(){
public Source resolve(String href, String base) throws TransformerException {
try {
URL url = new URL(href);
URLConnection connection = url.openConnection();
connection.setRequestProperty("User-Agent", "whatever");
return new StreamSource(connection.getInputStream());
} catch (IOException e) {
throw new RuntimeException(e);
}
}
});
OutputStream out = null;
try { fopFactory = FopFactory.newInstance(new File(CONFIG)); // Step 2: Set up output stream.
// Note: Using BufferedOutputStream for performance reasons (helpful with FileOutputStreams). out = new BufferedOutputStream(new FileOutputStream(OUTFILEPDF)); // Step 3: Construct fop with desired output format
Fop fop = fopFactory.newFop(MimeConstants.MIME_PDF, out); // Step 4: Setup JAXP using identity transformer
TransformerFactory factory = TransformerFactory.newInstance();
Transformer transformer = factory.newTransformer(); // identity transformer // Step 5: Setup input and output for XSLT transformation
// Setup input stream
Source src = new StreamSource(OUTFILEFO); // Resulting SAX events (the generated FO) must be piped through to FOP
Result res = new SAXResult(fop.getDefaultHandler());
// Step 6: Start XSLT transformation and FOP processing
transformer.transform(src, res); } catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
//Clean-up
try {
out.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}}

2.1.3

很多时候我们是使用word直接转的html,但是需要自己写二次渲染的代码,较为复杂,我是使用迂回方法,doc转xml,再用xml转换pdf,转换出来的pdf用pdfjs渲染即可实现和浏览器打开一样的预览,pdfjs预览方法详情见https://blog.csdn.net/liuxufeijidian/article/details/82260199





ending:大家都想看效果如何,https://github.com/litter-fish/transform,github获取改源码,配置好doc和docx文档即可实现转换,接下来会继续努力不间断优化和更新文档转换。