这篇文章将为大家详细讲解有关如何使用java实现在线预览，小编觉得挺实用的，因此分享给大家做个参考，希望大家阅读完这篇文章后可以有所收获。
具体内容如下所示：
###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。
###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;kppt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。
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