Java 获取图片的大小、宽、高

参考：https://www.cnblogs.com/hongten/archive/2012/11/26/hongten_java_ImageReader_BufferedImage.html 

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 Picture {
    public static void main(String[] args) throws FileNotFoundException, IOException {
        File picture = new File("E:/PrintScreen/StarSky.jpg");
        BufferedImage sourceImg = ImageIO.read(new FileInputStream(picture));
        
        System.out.println(String.format("Size: %.1f KB", picture.length()/1024.0));
        System.out.println("Width: " + sourceImg.getWidth());
        System.out.println("Height: " + sourceImg.getHeight());
    }
}

这个没看懂！

import java.io.File;
import java.io.IOException;
import java.util.Iterator;

import javax.imageio.ImageIO;
import javax.imageio.ImageReader;
import javax.imageio.stream.ImageInputStream;

public class Picture {
    public static void main(String[] args) {
        String srcPath = "E:/PrintScreen/1.jpg";
        
        File file = new File(srcPath);
        try {
            Iterator<ImageReader> readers = ImageIO.getImageReadersByFormatName("jpg");
            ImageReader reader = (ImageReader) readers.next();
            ImageInputStream iis = ImageIO.createImageInputStream(file);
            reader.setInput(iis, true);
            System.out.println(" " + reader.getWidth(0));
            System.out.println("height: " + reader.getHeight(0));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

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注意：图片是预先存放在Java Project下的Package中

import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.net.URL;

import javax.imageio.ImageIO;

public class GetImageSize {
    public static void main(String[] args) throws IOException {
        BufferedImage bi = null;
        
        try {
            URL u = GetImageSize.class.getClassLoader().getResource("images/background.png");
            bi = ImageIO.read(u);
        } catch (IOException e) {
            e.printStackTrace();
        }
        Image img = bi;
        
        System.out.println(img.getWidth(null));
        System.out.println(img.getHeight(null));
    }
}