import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import javax.imageio.ImageIO;

public class CalPit {
 public static void main(String[] args) throws FileNotFoundException, IOException {
  File picture = new File("C:/Users/Administrator/Pictures/我的图片/neusoft.png");
  BufferedImage sourceImg =ImageIO.read(new FileInputStream(picture));
  System.out.println(String.format("%.1f",picture.length()/1024.0));
  System.out.println(sourceImg.getWidth());
  System.out.println(sourceImg.getHeight());
 }
}

原帖地址：http://blog.csdn.net/huangyunzeng2008/article/details/8505640