What is the best way to scale images in Java?

Question

I have a web application written in Java (Spring, Hibernate/JPA, Struts2) where users can upload images and store them in the file system. I would like to scale those images

Answer 1

I know this is a very old question, but I got my own solution for this using standard Java API

import java.awt.*;
import java.awt.event.*;
import javax.imageio.*
import java.awt.image.*;

BufferedImage im, bi, bi2;
Graphics2D gfx;
int imWidth, imHeight, dstWidth, dstHeight;
int DESIRED_WIDTH = 500, DESIRED_HEIGHT = 500;

im = ImageIO.read(new File(filePath));
imWidth = im.getWidth(null);
imHeight = im.getHeight(null);

dstWidth = DESIRED_WIDTH;
dstHeight = (dstWidth * imHeight) / imWidth;

bi = new BufferedImage(dstWidth, dstHeight, im.getType());

gfx = bi.createGraphics();
gfx.drawImage(im, 0, 0, dstWidth, dstHeight, 0, 0, imWidth, imHeight, null);

bi2 = new BufferedImage(DESIRED_WIDTH, DESIRED_HEIGHT, im.getType());
gfx = bi2.createGraphics();

gfx.drawImage(bi, 0, 0, DESIRED_WIDTH, DESIRED_HEIGHT, null);

ImageIO.write(bi2, "jpg", new File(filePath));

I am sure it can be improved and adapted.