java中Swing中URl怎么使用

Question

package com.ten;

import java.awt.Container;

import java.net.URL;

import javax.swing.ImageIcon;

import javax.swing.JFrame;

import javax.swing.JLabel;

import javax.swing.*;

public class MyImageIcon extends JFrame{

public MyImageIcon(){

Container con = getContentPane();

JLabel jl = new JLabel("这是一个JFrame窗体",JLabel.CENTER);

URL url = MyImageIcon.class.getResource("imageButton.jap");

Icon icon = new ImageIcon(url);

jl.setIcon(icon);

jl.setHorizontalAlignment(SwingConstants.CENTER);

jl.setOpaque(true);

con.add(jl);

setSize(250,100);

setVisible(true);

setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);

}

public static void main(String[] args){

new MyImageIcon();

}

}