想对jpeg格式图像进行压缩（不是缩略图）,压缩后还是jpeg格式,在java中如何实现

try {

// 压缩前的JPEG文件
File srcFile = new File("c:\\src.jpg");
// 压缩前后的JPEG文件
File dstFile = new File("c:\\dst.jpg");
// 压缩百分比
float quality = 0.75f;

BufferedImage srcImage = ImageIO.read(srcFile);

Iterator it = ImageIO.getImageWritersBySuffix("jpg");
if (it.hasNext()) {
FileImageOutputStream fileImageOutputStream = new FileImageOutputStream(dstFile);
ImageWriter iw = (ImageWriter) it.next();
ImageWriteParam iwp = iw.getDefaultWriteParam();
iwp.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
iwp.setCompressionQuality(quality);
iw.setOutput(fileImageOutputStream);
iw.write(null, new IIOImage(srcImage, null, null), iwp);
iw.dispose();
fileImageOutputStream.flush();
fileImageOutputStream.close();
}
} catch (FileNotFoundException ex) {
ex.printStackTrace();
} catch (IOException ex) {
ex.printStackTrace();
}