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Categories / Java Tutorial / 2D Graphics

 

Detect the file type of the input stream prior to reading the image

import java.awt.image.BufferedImage; import java.net.URL; import java.util.Iterator; import javax.imageio.ImageIO; import javax.imageio.ImageReader; import javax.imageio.stream.ImageInputStream; public class Main {   public static void main(String[] argv) throws Exception {     ImageInputStream imageStream = ImageIO.createImageInputStream(new URL("").openStream());     Iterator<ImageReader> readers = ImageIO.getImageReaders(imageStream);     ImageReader reader = null;     if (!readers.hasNext()) {       imageStream.close();       return;     } else {       reader = readers.next();     }     String formatName = reader.getFormatName();     if (!formatName.equalsIgnoreCase("jpeg") && !formatName.equalsIgnoreCase("png")         && !formatName.equalsIgnoreCase("gif")) {       imageStream.close();       return;     }     reader.setInput(imageStream, true, true);     BufferedImage theImage = reader.read(0);     reader.dispose();     imageStream.close();   } }