Java Graphics - 如何读取图像文件并获取其大小

import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

import javax.imageio.ImageIO;

public class Main {
  BufferedImage img;

  public static int getWidthFromImage(String filename) {
    BufferedImage image;
    try {
      image = ImageIO.read(new File(filename));
      return image.getWidth();
    } catch (IOException e) {
      System.out.println(e.getMessage());
      e.printStackTrace();
    }
    return -1;
  }

  public static void main(String args[]) {
    System.out.print("The width of the image in pixels is: "
        + getWidthFromImage(args[0]));
  }
}