java如何将pdf转换成image

package pdf; 
 
import java.awt.image.BufferedImage; 
import java.io.File; 
import java.io.IOException; 
import java.util.Date; 
import java.util.List; 
 
import javax.imageio.ImageIO; 
 
import org.apache.pdfbox.pdmodel.PDDocument; 
import org.apache.pdfbox.pdmodel.PDPage; 
 
public class PDFBox { 
   
  @SuppressWarnings("rawtypes") 
  public static void main(String[] args) throws IOException { 
    String p=System.getProperty("user.dir") + "/"+"zk.pdf";   
     
    PDDocument doc = PDDocument.load(p); 
    int pageCount = doc.getNumberOfPages(); 
    System.out.println(pageCount); 
    Date start = new Date(); 
    try { 
      List pages = doc.getDocumentCatalog().getAllPages(); 
      for(int i=0;i<pages.size();i++){ 
        PDPage page = (PDPage) pages.get(i); 
        @SuppressWarnings("unused") 
        int width = new Float(page.getTrimBox().getWidth()).intValue(); 
        @SuppressWarnings("unused") 
        int height = new Float(page.getTrimBox().getHeight()).intValue(); 
        BufferedImage image = page.convertToImage(); 
        ImageIO.write(image, "jpg", new File("img" + File.separator + (i + 1) + ".jpg")); 
        System.out.println("image in the page -->"+(i+1)); 
      } 
    } catch (Exception e) { 
      e.printStackTrace(); 
    }finally{ 
      if(doc != null){ 
        doc.close(); 
      } 
    } 
    Date end = new Date(); 
    System.out.println(end.getTime()-start.getTime()); 
    System.out.println("over"); 
  } 
   
} 

package pdf; 
 
import java.awt.Image; 
import java.awt.Rectangle; 
import java.awt.image.BufferedImage; 
import java.io.File; 
import java.io.FileOutputStream; 
import java.io.IOException; 
import java.io.RandomAccessFile; 
import java.nio.MappedByteBuffer; 
import java.nio.channels.FileChannel; 
 
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 PDFRenderer { 
   
  public static void main(String[] args) throws IOException{ 
    String pdfRealePath=System.getProperty("user.dir") + "/"+"zk.pdf"; 
    File file = new File(pdfRealePath); 
    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,true,true); 
      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("img" + File.separator + (i + 1) + ".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(); 
      System.out.println("image in the page -->"+(i+1)); 
    } 
  } 
}