[web] java 将pdf转化为图片

Z时代
2024-01-10
分类：综合
java
官方文档 https://java.net/projects/pdf-renderer/
package com.wa.xwolf.sblog.controller;
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.io.Writer;
import java.lang.reflect.Method;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.security.AccessController;
import java.security.PrivilegedAction;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
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;
/**
 * pdf 在线预览实现
 * @author xwolf
 * @Date 2015-06-16 09:32
 *
 */
public class PDFOnlineViewController  {
     private static void changePdfToImg() {  
            try {  
            File file = new File("G:\\view.pdf");  
            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);  
           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()));  
            Image img = page.getImage(rect.width, rect.height, 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);  
            FileOutputStream out = new FileOutputStream("G:\\" + i + ".jpg"); // 输出到文件流  
           JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);  
            JPEGEncodeParam param2 = encoder.getDefaultJPEGEncodeParam(tag);  
            param2.setQuality(1f, false);// 1f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();  
            }  
        }  
        @SuppressWarnings("unchecked")
        private 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;  
            }  
            });  
        }  
        public static void main(String[] args) {
            changePdfToImg();
        }
}