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
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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; } }} |
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持服务器之家。
原文链接：https://blog.csdn.net/z69183787/article/details/12616099
