java实现pdf按页切分成图片

package com.ces.component.pictrueCut.entity;
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;  

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 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);
            /** 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;
            }
        });
    }
}