Create thumbnails and avatars in Java

Avatars–icon-sized images used to represent people online–are usually square. Consider, Facebook avatars are 50 by 50 pixel images. Most source images are not square, however. Cameras typically take pictures with a 4:3 aspect ratio. So to create an avatar from an image, you must do two things: crop it to a square and resize it to your desired icon size.

Thumbnails present a similar challenge.  When displaying thumbnails in an image gallery, you typically want to enforce at least one of width|height to be the same for all images to avoid a very sloppy look.  The cleanest look is achieved with square thumbnails of equal size, though the necessary cropping may not be desireable in every case.
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How to load an image from a URL in java

Assuming you want to load the image from the URL into memory in order to display or manipulate it:

try {
    URL imageUrl = new URL("http//example/image.jpg");
    InputStream in = imageUrl.openStream();
    BufferedImage image = ImageIO.read(in);
    in.close();
}
catch (IOException ioe) {
    //log the error
}

Loading an image from a URL is as simple as that.  Now you’ve got a BufferedImage.

It can be even simpler, and if all you are doing is cropping or resizing the image, you may be interested in a little java image utility I wrote.  Using my ImageLoader and Image classes, the code would look like:

try {
    Image image = ImageLoader.fromUrl("http//example/image.jpg");
}
catch (IOException ioe) {
    //log the error
}

The Image class is a wrapper on a BufferedImage and provides some useful methods for cropping, resizing, and writing (saving) the image.  Let me know in the comments below if you’ve found this helpful.