<dependency>   
  <groupId>org.apache.pdfbox</groupId>   
  <artifactId>fontbox</artifactId>   
  <version>2.0.1</version> 
</dependency> 
<dependency>  
  <groupId>org.apache.pdfbox</groupId>  
  <artifactId>pdfbox</artifactId> 
  <version>2.0.1</version> 
</dependency>

public class PDFToImgUtil {
 
 private static Logger logger = LoggerFactory.getLogger(PDFToImgUtil.class);
 
 
 /**
 * 獲取PDF總頁數
 * @throws IOException 
 */
 public static int getPDFNum(String fileUrl) throws IOException {
 PDDocument pdDocument = null;
 int pages = 0;
 try {
  pdDocument = getPDDocument(fileUrl);
  pages = pdDocument.getNumberOfPages();
 } catch (Exception e) {
  e.printStackTrace();
   logger.error(e.getMessage(),e);
 } finally {
  if (pdDocument != null) {
  pdDocument.close();
  }
 }
 return pages;
 }
 
 
 /**
 * PDF轉圖片 根據頁碼一頁一頁轉 
 * @throws IOException 
 * imgType:轉換后的圖片類型 jpg,png
 */
 public static void PDFToImg(OutputStream sos,String fileUrl,int page,String imgType) throws IOException {
 PDDocument pdDocument = null;
 /* dpi越大轉換后越清晰，相對轉換速度越慢 */
 int dpi = 100;
 try {
  pdDocument = getPDDocument(fileUrl);
  PDFRenderer renderer = new PDFRenderer(pdDocument);
  int pages = pdDocument.getNumberOfPages();
  if (page <= pages && page > 0) {
  BufferedImage image = renderer.renderImageWithDPI(page,dpi);
  ImageIO.write(image, imgType, sos);
  }
 } catch (Exception e) {
  e.printStackTrace();
   logger.error(e.getMessage(),e);
 } finally {
  if (pdDocument != null) {
  pdDocument.close();
  }
 }
 
 }
 
 
 private static PDDocument getPDDocument(String fileUrl) throws IOException {
 File file = new File(fileUrl);
 FileInputStream inputStream = new FileInputStream(file);
   return PDDocument.load(inputStream);
 }
 
}