文件在線預覽doc，docx轉換pdf（一）
1. 前言
文檔轉換是一個是一塊硬骨頭，可是也是必不可少的，咱們正好作的知識庫產品中，也面臨着一樣的問題，文檔轉換，精準的全文搜索，知識的轉換率，是知識庫產品的基本要素，初識閱讀時同時絞盡腦汁，本身開發?，集成第三方？都是中小企業面臨的一大難題…….
本身在網上搜索着找到poi開源出來的不少例子，最開始是用poi把全部文檔轉換爲html，
1) 在github上面找到一個https://github.com/litter-fish/transform完整的demo，你想要的轉換基本都提供，初學者能夠參照實現轉換出來的基本樣子，達到通用級別，須要本身花不少功夫。此開源代碼是基於poi和itext（pdf）的轉換方式。
2) https://gitee.com/kekingcn/file-online-preview這是開源中國提供的一個源碼，基於jodconverter，原理是調用windows，另存爲的組件，實現轉換。
3) 收費產品例如【永中office】【office365】【idocv】、【https://downloads.aspose.com/words/java】
2. 轉換思路
本身在嘗試過不少後，也與永中集成了文檔轉換，發現，要想完成預覽的品質，必須的作二次渲染。畢竟永中作了十幾年文檔轉換咱們不能比的，本身琢磨後，發現一個勉強靠譜的思路，doc和docx都轉換爲pdf實現預覽。都是在基於poi的基礎上。
2.1. Doc轉換pdf
1) Doc轉換爲xml
/**
* doc轉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轉換爲pdf
這裏我是使用fop經過xml轉換爲pdf，也是最近欣喜的一個發現，poi官網推薦的我一直沒去仔細看，裏面的架包和永中的不少高清包，如出一轍，如今貌似路子對了。有興趣者研究去吧。個人源碼已經在githubhttps://github.com/liuxufeijidian/file.convert.master/tree/master上面，環境已經配置好，須要準備好doc和docx文檔便可。
/*
* xml 轉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
不少時候咱們是使用word直接轉的html，可是須要本身寫二次渲染的代碼，較爲複雜，我是使用迂迴方法，doc轉xml，再用xml轉換pdf，轉換出來的pdf用pdfjs渲染便可實現和瀏覽器打開同樣的預覽，pdfjs預覽方法詳情見https://blog.csdn.net/liuxufeijidian/article/details/82260199
ending：你們都想看效果如何，https://github.com/litter-fish/transform，github獲取改源碼，配置好doc和docx文檔便可實現轉換，接下來會繼續努力不間斷優化和更新文檔轉換。