通过 PDFRenderer 实现预览PDF 功能

需要一个jar PDFRenderer-0.9.0.jar 

http://java.net/downloads/pdf-renderer/PDFRenderer-0.9.0.jar 

package com.wonders.stpt.attach.action;import java.awt.Image;import java.awt.Rectangle;import java.awt.image.BufferedImage;import java.io.File;import java.io.FileInputStream;import java.io.FilenameFilter;import java.io.FileOutputStream;import java.io.InputStream;import java.io.OutputStream;import java.io.RandomAccessFile;import java.nio.ByteBuffer;import java.nio.channels.FileChannel;import java.util.Arrays;import java.util.Comparator;import javax.imageio.*;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.apache.struts2.convention.annotation.Action;import org.apache.struts2.convention.annotation.Namespace;import org.apache.struts2.convention.annotation.ParentPackage;import org.apache.struts2.convention.annotation.Result;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.beans.factory.annotation.Qualifier;import org.springframework.context.annotation.Scope;import org.springframework.stereotype.Component;import com.sun.image.codec.jpeg.JPEGCodec;import com.sun.image.codec.jpeg.JPEGImageEncoder;import com.sun.pdfview.PDFFile;import com.sun.pdfview.PDFPage;import com.wonders.stpt.attach.model.vo.UploadFile;import com.wonders.stpt.attach.service.FjshService;import com.wonders.stpt.userMsg.action.AbstractParamAction;@SuppressWarnings("serial")@ParentPackage("struts-default")@Namespace(value="/attach")@Component("attachViewerAction")@Scope("prototype")public class AttachViewerAction extends AbstractParamAction{private FjshService fjshService;private final int maxPage = 30; public FjshService getFjshService() {return fjshService;}@Autowired(required=false)public void setFjshService(@Qualifier("fjshService")FjshService fjshService) {this.fjshService = fjshService;}/** * PDF文档在线以图片格式预览. *  */@Action(value="/pdfPreview",results={@Result(name="pdf",location="/attachPreview/pdfViewer.jsp")})public String pdfPreview() {//按fileId查找出该文件的路径以及文件名.//该部分代码copy自附件上传组件HttpServletRequest request = servletRequest;HttpServletResponse response = servletResponse;String fileId = request.getParameter("fileId");if("".equals(fileId) || null == fileId) {servletRequest.setAttribute("state", "f");return "pdf";}UploadFile upFile = this.fjshService.loadFileById(fileId);if(upFile == null) {servletRequest.setAttribute("state", "f");return "pdf";}String path = upFile.getPath();// 文件所在磁盘路径.String fileName = upFile.getFileAllName();// 真实文件名.String saveFileName = upFile.getSaveFileName();// 磁盘上的文件名.String version = upFile.getVersion();if ("old".equals(request.getParameter("ver"))){if (version != null){saveFileName = saveFileName.replace(".dat","_v"+version+".dat");}}//当前应用绝对路径String appPath =  request.getSession().getServletContext().getRealPath ("");    String imageSavePath = appPath + "\\preview_images\\";    //按照文件路径读取PDF文档，并将其按页转换为图片String filePath = path + saveFileName ;if(filePath == null || "".equals(filePath)) {servletRequest.setAttribute("state", "f");return "pdf";}else {PDFFile pdfFile = this.getPdfFile(filePath);if(this.pdf2Images(pdfFile,imageSavePath,String.valueOf(upFile.getId()))) { //如果转换成功return "pdf";}else {servletRequest.setAttribute("state", "f");return "pdf";}}}/** * 图片文件在线预览 *  */@Action(value="/imagePreview",results={@Result(name="image",location="/attachPreview/imageViewer.jsp")})public String imagePreview() {//按fileId查找出该文件的路径以及文件名.//该部分代码copy自附件上传组件HttpServletRequest request = servletRequest;HttpServletResponse response = servletResponse;String fileId = request.getParameter("fileId");if("".equals(fileId) || null == fileId) {servletRequest.setAttribute("state", "f");return "image";}UploadFile upFile = this.fjshService.loadFileById(fileId);if(upFile == null) {servletRequest.setAttribute("state", "f");return "image";}String path = upFile.getPath();// 文件所在磁盘路径.String fileName = upFile.getFileAllName();// 真实文件名.String saveFileName = upFile.getSaveFileName();// 磁盘上的文件名.String version = upFile.getVersion();if ("old".equals(request.getParameter("ver"))){if (version != null){saveFileName = saveFileName.replace(".dat","_v"+version+".dat");}}//当前应用绝对路径String appPath =  request.getSession().getServletContext().getRealPath ("");    String imageSavePath = appPath + "\\preview_images\\";    //按照文件路径读取文件String filePath = path + saveFileName ;if(filePath == null || "".equals(filePath)) {servletRequest.setAttribute("state", "f");return "image";}else {//如果成功读取文件String imageName = String.valueOf(upFile.getId());String extName = upFile.getFileExtName();if(getImageFile(filePath,imageSavePath,imageName,extName)) {return "image";}else {servletRequest.setAttribute("state", "f");return "image";}}}/** * image文件读取.  * @param filePath -- 待读取文件的路径. * @param imageSavePath -- 图片保存路径. * @param imageName -- 图片文件保存后的文件名称（包括后缀）. * @return boolean instance. */private boolean getImageFile(String filePath,String imageSavePath,String dirName,String extName) {String path = imageSavePath + dirName + "\\";File file = new File(path);if(!file.exists()){//判断以文件名命名的文件夹是否存在.file.mkdirs();}try {InputStream is = new FileInputStream(filePath);String imagePath = path + dirName + "." + extName;FileOutputStream os = new FileOutputStream(imagePath);  // 输出到文件流.byte[] buffer = new byte[1024];int n = 0;while ((n = is.read(buffer, 0, 1024)) > 0) {os.write(buffer, 0, n);}os.close();is.close();} catch (Exception ex) {ex.printStackTrace();return false;}servletRequest.setAttribute("state", "s");servletRequest.setAttribute("dirName", dirName);servletRequest.setAttribute("imageName", dirName + "." + extName);return true;}/** * PDF文档读取.  * @param filePath -- 待读取PDF文件的路径. * @return null 或者 PDFFile instance. */private PDFFile getPdfFile(String filePath) {try {//load a pdf file from byte buffer.File file = new File(filePath);RandomAccessFile raf = new RandomAccessFile(file, "r");FileChannel channel = raf.getChannel();ByteBuffer buf = channel.map(FileChannel.MapMode.READ_ONLY, 0,channel.size());PDFFile pdfFile = new PDFFile(buf);return pdfFile;} catch (Exception ex) {ex.printStackTrace();}return null;}/** * PDF文档按页转换为图片. * @param pdfFile -- PDFFile instance * @param imageSavePath -- 图片保存路径. * @param fileName -- 保存图片文件夹名称. */private boolean pdf2Images(PDFFile pdfFile,String imageSavePath,String fileName) {if(pdfFile == null ) { //待转换文档不存在，返回false.return false;}//将转换后图片存放于path路径下String path = imageSavePath + fileName + "\\";File filePath = new File(path);if(!filePath.exists()){//判断以文件名命名的文件夹是否存在.filePath.mkdirs();}//取得当前文件夹下的所有jpg格式的文件名.String[] imageNames = filePath.list(new ImageFilter());if(imageNames.length == 0) {  //当前文件夹下没有文件.//将pdf文档按页转为图片.String imagePath = "";try {//对转换页数进行限制,最多只转换前maxPage页.int pages = pdfFile.getNumPages();if(pages > maxPage){pages = maxPage;}for (int i = 1; i <= pages; i++) {// draw the page to an imagePDFPage page = pdfFile.getPage(i);// get the width and height for the doc at the default zoomRectangle rect = new Rectangle(0,    0,    (int) page.getBBox().getWidth(),    (int) page.getBBox().getHeight());// generate the imageImage img = page.getImage(rect.width, rect.height, // width & height  rect, // clip rect  null, // null for the ImageObserver  true, // fill background with white  true // block until drawing is done  );BufferedImage tag = new BufferedImage(rect.width,   rect.height,  BufferedImage.TYPE_INT_RGB);tag.getGraphics().drawImage(img, 0,0,rect.width,rect.height,null);imagePath = path + i + ".jpg";FileOutputStream out = new FileOutputStream(imagePath);  // 输出到文件流.JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);encoder.encode(tag); // JPEG编码.out.close();}}catch (Exception ex) {ex.printStackTrace();return false;}}//取得当前文件夹下的所有jpg格式的文件名.imageNames = filePath.list(new ImageFilter());//对文件名排序.Arrays.sort(imageNames,new FileNameComparator());servletRequest.setAttribute("state", "s");servletRequest.setAttribute("fileName", fileName);servletRequest.setAttribute("imageNames", imageNames);return true;}//图片后缀名过滤类//图片jpg过滤器类class ImageFilter implements FilenameFilter{ public boolean isImageFile(String fileName){  if(fileName.toLowerCase().endsWith("jpg")) {  return true;  }else {  return false;  }   }  public ImageFilter() {}  public boolean accept(File dir,String name){ return isImageFile(name);  }}//文件名称比较类class FileNameComparator implements Comparator {public final int compare(Object first, Object second) {   String[] fir = ((String)first).split("\\.");   String[] sec = ((String)second).split("\\.");      int firstPage = Integer.parseInt(fir[0]);   int secondPage = Integer.parseInt(sec[0]);   int diff = firstPage - secondPage;   if (diff > 0)    return 1;   if (diff < 0)    return -1;   else    return 0;}}}

转自：http://blog.csdn.net/z69183787/article/details/12616099