java使用renderer将pdf按页转换为图片

import java.awt.image;

import java.awt.rectangle;

import java.awt.image.bufferedimage;

import java.io.file;

import java.io.filenotfoundexception;

import java.io.fileoutputstream;

import java.io.ioexception;

import java.io.randomaccessfile;

import java.lang.reflect.method;

import java.nio.mappedbytebuffer;

import java.nio.channels.filechannel;

import java.security.accesscontroller;

import java.security.privilegedaction;

//如果com.sun.image找不到，就是eclipse默认把这些受访问限制的api设成了error。只要把windows-preferences-java-complicer-errors/warnings里面的deprecated and restricted api中的forbidden references(access rules)选为warning就可以编译通过

import com.sun.image.codec.jpeg.jpegcodec;

import com.sun.image.codec.jpeg.jpegencodeparam;

import com.sun.image.codec.jpeg.jpegimageencoder;

import com.sun.pdfview.pdffile;

import com.sun.pdfview.pdfpage;

public class pdftoimage {

  public static void main(string[] args) {

  string instructiopath= "e:/临时文件1.pdf" ;

  string picturepath = "e:/临时文件1/" ;

  changepdftoimg(instructiopath,picturepath);

  }

   public static int changepdftoimg(string instructiopath,string picturepath) {

     int countpage = 0 ;

     try {

       //instructiopath ="d:/instructio/2015-05-16/android 4编程入门经典.pdf"

       //picturepath = "d:/instructio/picture/2015-05-16/";

       file file = new file(instructiopath);

       randomaccessfile raf = new randomaccessfile(file, "r" );

       filechannel channel = raf.getchannel();

       mappedbytebuffer buf = channel.map(filechannel.mapmode.read_only,

           0 , channel.size());

       pdffile pdffile = new pdffile(buf);

       //创建图片文件夹

       file dirfile = new file(picturepath);

         if (!dirfile.exists()){

            dirfile.mkdirs();

         }

       //获得图片页数

       countpage = pdffile.getnumpages();

       for ( int i = 1 ; i <= pdffile.getnumpages(); i++) {

         pdfpage page = pdffile.getpage(i);

         rectangle rect = new rectangle( 0 , 0 , (( int ) page.getbbox()

             .getwidth()), (( int ) page.getbbox().getheight()));

         int n = 2 ;

         /** 图片清晰度（n>0且n<7）【pdf放大参数】 */

         image img = page.getimage(rect.width * n, rect.height * n,

             rect, /** 放大pdf到n倍，创建图片。 */

             null , /** null for the imageobserver */

             true , /** fill background with white */

             true /** block until drawing is done */

         );

         bufferedimage tag = new bufferedimage(rect.width * n,

             rect.height * n, bufferedimage.type_int_rgb);

         tag.getgraphics().drawimage(img, 0 , 0 , rect.width * n,

             rect.height * n, null );

         /**

          * file imgfile = new file("d:\\work\\mybook\\filesnew\\img\\" +

          * i + ".jpg"); if(imgfile.exists()){

          * if(imgfile.createnewfile()) { system.out.println("创建图片："+

          * "d:\\work\\mybook\\filesnew\\img\\" + i + ".jpg"); } else {

          * system.out.println("创建图片失败！"); } }

          */

         fileoutputstream out = new fileoutputstream(picturepath+ "/" + i

             + ".png" );

         /** 输出到文件流 */

         jpegimageencoder encoder = jpegcodec.createjpegencoder(out);

         jpegencodeparam param2 = encoder.getdefaultjpegencodeparam(tag);

         param2.setquality(1f, true );

         /** 1f~0.01f是提高生成的图片质量 */

         encoder.setjpegencodeparam(param2);

         encoder.encode(tag);

         /** jpeg编码 */

         out.close();

       }

       channel.close();

       raf.close();

       /*unmap(buf);*/  //pdf转化成图片后，释放mappedbytebuffer资源。调用unmap(buf);无效。

       /** 如果要在转图片之后删除pdf，就必须要这个关闭流和清空缓冲的方法 */

     } catch (filenotfoundexception e) {

       e.printstacktrace();

     } catch (ioexception e) {

       e.printstacktrace();

     }

     return countpage;

   }

   @suppresswarnings ( "unchecked" )

   public static void unmap( final object buffer) {

     accesscontroller.doprivileged( new privilegedaction() {

       public object run() {

         try {

           method getcleanermethod = buffer.getclass().getmethod(

               "cleaner" , new class [ 0 ]);

           getcleanermethod.setaccessible( true );

           sun.misc.cleaner cleaner = (sun.misc.cleaner) getcleanermethod

               .invoke(buffer, new object[ 0 ]);

           cleaner.clean();

         } catch (exception e) {

           e.printstacktrace();

         }

         return null ;

       }

     });

   }

}

method m = filechannelimpl. class .getdeclaredmethod( "unmap" ,

     mappedbytebuffer. class );

    m.setaccessible( true );

    m.invoke(filechannelimpl. class , buf);