<%@ page import="java.io.*, javax.imageio.ImageIO, java.awt.image.BufferedImage" %>
<%
// Get the uploaded file
Part filePart = request.getPart("file");
String fileName = filePart.getSubmittedFileName();
InputStream fileContent = filePart.getInputStream();
// Load the JPG image
BufferedImage jpgImage = ImageIO.read(fileContent);
// Create a new PNG image and write the JPG image to it
BufferedImage pngImage = new BufferedImage(jpgImage.getWidth(), jpgImage.getHeight(), BufferedImage.TYPE_INT_ARGB);
pngImage.createGraphics().drawImage(jpgImage, 0, 0, null);
// Save the PNG image to a file
String pngFileName = fileName.replace(".jpg", ".png");
File pngFile = new File(pngFileName);
ImageIO.write(pngImage, "png", pngFile);
%>
JPG to PNG Converter - Result