稍微改动一下就可以显示所要大小的图片了。

import java.io.*;
import java.awt.image.*;
import javax.swing.*;
import javax.imageio.*;
import java.awt.*;

public class Test {
    public Test() {}

    public static void main(String[] args) {
        JFrame frame = new JFrame();
        Container cont = frame.getContentPane();
        JMenu jmuEdit = new JMenu("edit");
        JMenuItem jmuiPaste;
        File imagefile = new File("f:/menu.gif");
        try {
            BufferedImage bufferedImage = ImageIO.read(imagefile);
    //此处的参数应为BufferedImage.SCALE_SMOOTH
            Image image = new ImageIcon(bufferedImage).getImage().
                          getScaledInstanc(16,16,BufferedImage.SCALE_SMOOTH);
            ImageIcon imageicon = new ImageIcon(image);
            jmuEdit.add(jmuiPaste = new JMenuItem("Paste", imageicon));
        } catch (IOException e) {}
        JMenuBar mbar = new JMenuBar();
        mbar.add(jmuEdit);
        frame.setJMenuBar(mbar);
        frame.setBounds(400, 400, 400, 300);
        frame.setVisible(true);
    }
}

try
        {
            File imagefile=new File("paste.png");
            BufferedImage bufferedImage = ImageIO.read(imagefile);
            // bufferedImage.getScaledInstance(16,16,BufferedImage.SCALE_FAST);
           
             
            Image changeimage = new ImageIcon(bufferedImage).getImage().
            getScaledInstance(16,16,BufferedImage.SCALE_FAST);

            ImageIcon imageicon=new ImageIcon(changeimage);
            jmuEdit.add(jmuiPaste=new JMenuItem("粘贴(P)",imageicon));
        } catch (IOException e)
        {
            e.printStackTrace();
        }

sorry,我试过用BufferedImage.SCALE_FAST也行，我认为可能是ImageIcon imageicon=new ImageIcon(changeimage);这句我原来的参数类型是BufferedImage  或bufferedImage.getScaledInstance(16,16,BufferedImage.SCALE_FAST);没达到改变大小的效果 ，我也不懂，希望大家赐教，说说自己的看法