将图片包装到Jframe

这可能更简单：JLabel在contentpane中使用FlowLayout：

import java.awt.FlowLayout;import java.awt.Rectangle;import java.awt.image.BufferedImage;import java.io.IOException;import java.net.URL;import javax.imageio.ImageIO;import javax.swing.ImageIcon;import javax.swing.Jframe;import javax.swing.JLabel;public class WarpImage {    public static void main(String[] args) throws IOException {        displayImage();    }    private static void displayImage() throws IOException{        URL url = new URL("http://www.digitalphotoartistry.com/rose1.jpg");        BufferedImage image = ImageIO.read(url);        ImageIcon icon= new ImageIcon(image);        Jframe frame=new Jframe();         frame.setDefaultCloseOperation(Jframe.EXIT_ON_CLOSE);        frame.setLayout(new FlowLayout());        JLabel lbl= new JLabel();        lbl.setIcon(icon);        frame.add(lbl);        frame.pack();        //check size :        Rectangle bounds = lbl.getBounds();        System.out.println(bounds.getWidth() +"-"+ bounds.getHeight());        frame.setVisible(true);    }}