java使用PDFRenderer实现预览PDF功能

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测试数据parator;

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测试数据ponent;

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 ;

  }

  }

}