Java Graphics - 如何将图像从PNG更改为JPG与JPG ImageWriteParam

import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Locale;

import javax.imageio.IIOImage;
import javax.imageio.ImageIO;
import javax.imageio.ImageWriteParam;
import javax.imageio.ImageWriter;
import javax.imageio.plugins.jpeg.JPEGImageWriteParam;
import javax.imageio.stream.ImageOutputStream;

public class Main {

  public static void main(String[] args) throws Exception {
    BufferedImage img = ImageIO.read(new File("test.jpg"));
    writeJpegCompressedImage(img, "NEW.jpg");
  }

  private static void writeJpegCompressedImage(BufferedImage image,
      String outFile) throws IOException {
    float qualityFloat = 1f;
    ByteArrayOutputStream outStream = new ByteArrayOutputStream();

    ImageWriter imgWriter = ImageIO.getImageWritersByFormatName("jpg").next();
    ImageOutputStream ioStream = ImageIO.createImageOutputStream(outStream);
    imgWriter.setOutput(ioStream);

    JPEGImageWriteParam jpegParams = new JPEGImageWriteParam(
        Locale.getDefault());
    jpegParams.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
    jpegParams.setCompressionQuality(qualityFloat);

    imgWriter.write(null, new IIOImage(image, null, null), jpegParams);

    ioStream.flush();
    ioStream.close();
    imgWriter.dispose();

    OutputStream outputStream = new FileOutputStream(outFile);
    outStream.writeTo(outputStream);

  }
}