java使用PDFRenderer实现预览PDF功能

java使用PDFRenderer实现预览PDF功能

本文实例为大家分享了java使用PDFRenderer实现预览PDF功能，供大家参考，具体内容如下

需要一个jar 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 image

PDFPage page = pdfFile.getPage(i);

// get the width and height for the doc at the default zoom

Rectangle rect = new Rectangle(0,

0,

(int) page.getBBox().getWidth(),

(int) page.getBBox().getHeight());

// generate the image

Image 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;

}

}

}

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