java实现在线预览

简介

java实现在线预览功能是一个大家在工作中也许会遇到的需求，如果公司有钱，直接使用付费的第三方软件或者云在线预览服务就可以了，例如永中office、office web 365(http://www.officeweb365.com/)他们都有云在线预览服务，就是要钱0.0
如果想要免费的，可以用openoffice，还需要借助其他的工具(例如swfTools、FlexPaper等)才行，可参考这篇文章http://blog.csdn.net/z69183787/article/details/17468039，写的挺细的，实现原理就是：
1.通过第三方工具openoffice，将word、excel、ppt、txt等文件转换为pdf文件；
2.通过swfTools将pdf文件转换成swf格式的文件；
3.通过FlexPaper文档组件在页面上进行展示。
当然如果装了Adobe Reader XI，那把pdf直接拖到浏览器页面就可以直接打开预览，这样就不需要步骤2、3了，前提就是客户装了Adobe Reader XI这个pdf阅读器。
我这里介绍通过poi实现word、excel、ppt转html，这样就可以放在页面上了。

jar包 链接: https://pan.baidu.com/s/13o2CZTwM-Igx6wcoyEu_ug 密码: n95q

word转html

package wordToHtml;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.util.List;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import org.apache.commons.io.FileUtils;
import org.apache.poi.hwpf.HWPFDocument;
import org.apache.poi.hwpf.converter.PicturesManager;
import org.apache.poi.hwpf.converter.WordToHtmlConverter;
import org.apache.poi.hwpf.usermodel.Picture;
import org.apache.poi.hwpf.usermodel.PictureType;
import org.w3c.dom.Document;
public class PoiWordToHtml {
 public static void main(String[] args) throws Throwable {
  final String path = "D:\poi-test\wordToHtml\";
  final String file = "人员选择系分.doc";
  InputStream input = new FileInputStream(path + file);
  HWPFDocument wordDocument = new HWPFDocument(input);
  WordToHtmlConverter wordToHtmlConverter = new WordToHtmlConverter(
    DocumentBuilderFactory.newInstance().newDocumentBuilder()
      .newDocument());
  wordToHtmlConverter.setPicturesManager(new PicturesManager() {
   public String savePicture(byte[] content, PictureType pictureType,
     String suggestedName, float widthInches, float heightInches) {
    return suggestedName;
   }
  });
  wordToHtmlConverter.processDocument(wordDocument);
  List pics = wordDocument.getPicturesTable().getAllPictures();
  if (pics != null) {
   for (int i = 0; i < pics.size(); i++) {
    Picture pic = (Picture) pics.get(i);
    try {
     pic.writeImageContent(new FileOutputStream(path
       + pic.suggestFullFileName()));
    } catch (FileNotFoundException e) {
     e.printStackTrace();
    }
   }
  }
  Document htmlDocument = wordToHtmlConverter.getDocument();
  ByteArrayOutputStream outStream = new ByteArrayOutputStream();
  DOMSource domSource = new DOMSource(htmlDocument);
  StreamResult streamResult = new StreamResult(outStream);
  TransformerFactory tf = TransformerFactory.newInstance();
  Transformer serializer = tf.newTransformer();
  serializer.setOutputProperty(OutputKeys.ENCODING, "utf-8");
  serializer.setOutputProperty(OutputKeys.INDENT, "yes");
  serializer.setOutputProperty(OutputKeys.METHOD, "html");
  serializer.transform(domSource, streamResult);
  outStream.close();
  String content = new String(outStream.toByteArray());
  FileUtils.writeStringToFile(new File(path, "人员选择系分.html"), content, "utf-8");
 }
}

excel转html

package excelToHtml;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.List;

import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;

import org.apache.commons.io.FileUtils;
import org.apache.poi.hssf.converter.ExcelToHtmlConverter;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.hwpf.converter.PicturesManager;
import org.apache.poi.hwpf.converter.WordToHtmlConverter;
import org.apache.poi.hwpf.usermodel.Picture;
import org.apache.poi.hwpf.usermodel.PictureType;
import org.w3c.dom.Document;


public class PoiExcelToHtml {
    final static String path = "D:\poi-test\excelToHtml\";
     final static String file = "exportExcel.xls";
 public static void main(String args[]) throws Exception {

     InputStream input=new FileInputStream(path+file);
     HSSFWorkbook excelBook=new HSSFWorkbook(input);
     ExcelToHtmlConverter excelToHtmlConverter = new ExcelToHtmlConverter (DocumentBuilderFactory.newInstance().newDocumentBuilder().newDocument() );
     excelToHtmlConverter.processWorkbook(excelBook);
     List pics = excelBook.getAllPictures();
     if (pics != null) {
         for (int i = 0; i < pics.size(); i++) {
             Picture pic = (Picture) pics.get (i);
             try {
                 pic.writeImageContent (new FileOutputStream (path + pic.suggestFullFileName() ) );
             } catch (FileNotFoundException e) {
                 e.printStackTrace();
             }
         }
     }
     Document htmlDocument =excelToHtmlConverter.getDocument();
     ByteArrayOutputStream outStream = new ByteArrayOutputStream();
     DOMSource domSource = new DOMSource (htmlDocument);
     StreamResult streamResult = new StreamResult (outStream);
     TransformerFactory tf = TransformerFactory.newInstance();
     Transformer serializer = tf.newTransformer();
     serializer.setOutputProperty (OutputKeys.ENCODING, "utf-8");
     serializer.setOutputProperty (OutputKeys.INDENT, "yes");
     serializer.setOutputProperty (OutputKeys.METHOD, "html");
     serializer.transform (domSource, streamResult);
     outStream.close();

     String content = new String (outStream.toByteArray() );

     FileUtils.writeStringToFile(new File (path, "exportExcel.html"), content, "utf-8");
 }
}

ppt转html

其实只是ppt转图片，有了图片后放到页面上去，点击下一页就一张张显示就可以了。这里只介绍ppt转图片的过程。

package pptToImg;

import java.awt.Dimension;   
import java.io.File;   
import java.io.FileInputStream;   
import java.io.FileNotFoundException;   
import java.io.FileOutputStream;   
import java.io.IOException;   

import java.awt.Color;   
import java.awt.Dimension;   
import java.awt.Graphics2D;   
import java.awt.geom.Rectangle2D;   
import java.awt.image.BufferedImage;   

import org.apache.poi.hslf.model.TextRun;   
import org.apache.poi.hslf.record.Slide;   
import org.apache.poi.hslf.usermodel.RichTextRun;   
import org.apache.poi.hslf.usermodel.SlideShow;   

public class PPTtoImage {   
    public static void main(String[] args) {   
        // 读入PPT文件   
        File file = new File("D:/poi-test/pptToImg/test.ppt");   
        doPPTtoImage(file);   
    }   

    public static boolean doPPTtoImage(File file) {   
        boolean isppt = checkFile(file);   
        if (!isppt) {   
            System.out.println("The image you specify don't exit!");   
            return false;   
        }   
        try {   

            FileInputStream is = new FileInputStream(file);   
            SlideShow ppt = new SlideShow(is);   
            is.close();   
            Dimension pgsize = ppt.getPageSize();   
            org.apache.poi.hslf.model.Slide[] slide = ppt.getSlides();   
            for (int i = 0; i < slide.length; i++) {   
                System.out.print("第" + i + "页。");   

                TextRun[] truns = slide[i].getTextRuns();      
                for ( int k=0;k<truns.length;k++){      
                   RichTextRun[] rtruns = truns[k].getRichTextRuns();      
                  for(int l=0;l<rtruns.length;l++){      
                       int index = rtruns[l].getFontIndex();      
                        String name = rtruns[l].getFontName();                
                        rtruns[l].setFontIndex(1);      
                        rtruns[l].setFontName("宋体");  
//                        System.out.println(rtruns[l].getText());
                   }      
                }      
                BufferedImage img = new BufferedImage(pgsize.width,pgsize.height, BufferedImage.TYPE_INT_RGB);   

                Graphics2D graphics = img.createGraphics();   
                graphics.setPaint(Color.BLUE);   
                graphics.fill(new Rectangle2D.Float(0, 0, pgsize.width, pgsize.height));   
                slide[i].draw(graphics);   

                // 这里设置图片的存放路径和图片的格式(jpeg,png,bmp等等),注意生成文件路径   
                FileOutputStream out = new FileOutputStream("D:/poi-test/pptToImg/pict_"+ (i + 1) + ".jpeg");   
                javax.imageio.ImageIO.write(img, "jpeg", out);   
                out.close();   

            }   
            System.out.println("success!!");   
            return true;   
        } catch (FileNotFoundException e) {   
            System.out.println(e);   
            // System.out.println("Can't find the image!");   
        } catch (IOException e) {   
        }   
        return false;   
    }   

    // function 检查文件是否为PPT   
    public static boolean checkFile(File file) {   

        boolean isppt = false;   
        String filename = file.getName();   
        String suffixname = null;   
        if (filename != null && filename.indexOf(".") != -1) {   
            suffixname = filename.substring(filename.indexOf("."));   
            if (suffixname.equals(".ppt")) {   
                isppt = true;   
            }   
            return isppt;   
        } else {   
            return isppt;   
        }   
    }   

}  

ppt转图片有个缺陷，就是ppt里不是宋体的字有些可能会变成框框。 

以上都需要引入poi的jar包。 

要实现在线预览，只需把转换得到的html在新标签页打开或者镶嵌到某块区域就可以展现了。