Java--添加背景图片

package com.welcome;

import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.Image;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.net.URL;

import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;

import com.cranerpt.CraneRPT;
import com.monitor.Monitor;
import com.report.Report;
import com.storage.Storage;
import com.transport.Transport;

public class Welcome implements ActionListener{

    static int WIDTH=500;
    static int HEIGHT=500;
    static int XLoc=450;
    static int YLoc=200;

    JFrame jframe=new JFrame();
    JPanel jpanel=new JPanel();
    JPanel northJPanel=new JPanel();
    JPanel southJPanel=new JPanel();
    JLabel label=new JLabel();
    JButton reportButton=new JButton();
    JButton CraneRPTButton=new JButton();
    JButton StorageButton=new JButton();
    JButton TransportButton=new JButton();
    JButton MonitorButton=new JButton();    

    ImageIcon background = new ImageIcon("src/Image/12.JPG");
    JLabel backgroundLabel = new JLabel(background);//将背景图放在标签里。

    Container container=jframe.getContentPane();

    public Welcome()
    {
        jframe.setContentPane(jpanel);
        jframe.setSize(WIDTH, HEIGHT);
        jframe.setResizable(false);

        jframe.getLayeredPane().add(backgroundLabel, new Integer(Integer.MIN_VALUE));
        backgroundLabel.setBounds(0,0,jframe.getWidth(),jframe.getHeight());
        jframe.getLayeredPane().setLayout(null);

        jpanel.setOpaque(false);

        init();
        paint();

        reportButton.addActionListener(this);
        CraneRPTButton.addActionListener(this);
        StorageButton.addActionListener(this);
        TransportButton.addActionListener(this);
        MonitorButton.addActionListener(this);
    }
    public void init()
    {
        URL url=this.getClass().getResource("/Image/BOE_2.png");
        Image image=Toolkit.getDefaultToolkit().getImage(url);
        jframe.setIconImage(image);

        jframe.setTitle("Welcome");
        jframe.setSize(WIDTH,HEIGHT);
        jframe.setLocation(XLoc,YLoc);
        jframe.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        jframe.addWindowListener(
                new WindowAdapter(){
                    public void windowClosing(WindowEvent e){
                        System.exit(0);
                    }
                }
            );
    }
    public void paint()
    {
        reportButton.setText("Report");
        CraneRPTButton.setText("CraneRPT");
        StorageButton.setText("Storage");
        TransportButton.setText("Transport");
        MonitorButton.setText("Monitor");
        label.setText("欢迎界面");
        label.setFont(new Font("宋体",Font.BOLD|Font.PLAIN,25));

        reportButton.setFocusable(false);
        CraneRPTButton.setFocusable(false);
        StorageButton.setFocusable(false);
        TransportButton.setFocusable(false);
        MonitorButton.setFocusable(false);

        label.setBounds(170,100,300,40);
        reportButton.setBounds(80,200,100,35);
        CraneRPTButton.setBounds(210,200,100,35);
        StorageButton.setBounds(340,200,100,35);
        TransportButton.setBounds(80,300,100,35);
        MonitorButton.setBounds(210,300,100,35);

        backgroundLabel.add(label);
        backgroundLabel.add(reportButton);
        backgroundLabel.add(CraneRPTButton);
        backgroundLabel.add(StorageButton);
        backgroundLabel.add(TransportButton);
        backgroundLabel.add(MonitorButton);

        container.add(jpanel);

        jframe.setVisible(true);
    }

    @Override
    public void actionPerformed(ActionEvent e)
    {
        // TODO Auto-generated method stub
        if(e.getSource()==reportButton)
        {
            Report report=new Report();
        }
        if(e.getSource()==CraneRPTButton)
        {
            CraneRPT craneRpt=new CraneRPT();
        }
        if(e.getSource()==StorageButton)
        {
            Storage storage=new Storage();
        }
        if(e.getSource()==TransportButton)
        {
            Transport  transport =new Transport ();
        }
        if(e.getSource()==MonitorButton)
        {
            Monitor monitor=new Monitor();
        }
    }
    public static void main(String []args)
    {
        Welcome welcome=new Welcome();
    }

}

图片路径设置要正确才行！