import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
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 {
File file = new File("image.gif");
System.out.println(getFormatName(file));
InputStream is = new FileInputStream(file);
is.close();
System.out.println(getFormatName(is));
}
private static String getFormatName(Object o) {
try {
ImageInputStream iis = ImageIO.createImageInputStream(o);
Iterator iter = ImageIO.getImageReaders(iis);
if (!iter.hasNext()) {
return null;
}
ImageReader reader = (ImageReader) iter.next();
iis.close();
return reader.getFormatName();
} catch (IOException e) {
}
return null;
}
}