在Swing窗口中画图，如何使窗口最小化后图形不消失

菜鸟一个，最近做一个swing的项目，发现窗口的最小化，最大化都会导致画的线与图形消失，实际上是绘制方法没有写在paint（）里面，而是写在了按钮的监听事件中。

画线按钮代码，画线的方法写在监听事件内，所以每次窗口状态变化都会刷新，线条消失

package Service;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.RenderingHints;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.util.ArrayList;
import java.util.List;

import javax.swing.JButton;

import Util.PaintBayLinePanel;

//画线按钮
public class DrawButton_action implements ActionListener{
	private PaintBayLinePanel linePanel;
	private List xy;//用于存取左右岸坐标
	private JButton button;
	public DrawButton_action(PaintBayLinePanel linePanel,List xy,JButton button){
		this.linePanel = linePanel;
		this.xy = xy;
		this.button = button;
	}
	@Override
	public void actionPerformed(ActionEvent e) {
		// TODO Auto-generated method stub
		linePanel.addMouseListener(new MouseListener() {
			
			List li = new ArrayList();
			Graphics g;
	
			@Override
			public void mouseClicked(MouseEvent e) {
				// TODO Auto-generated method stub
				Point p1 = new Point();
				Point p2 = new Point();
				int[] point_XY = new int[4];//暂存点的坐标
				li.add(e.getPoint());
				if (li.size() % 2 == 0) {
					g = linePanel.getGraphics();
					((Graphics2D) g).setRenderingHint(RenderingHints.KEY_ANTIALIASING , RenderingHints.VALUE_ANTIALIAS_ON);//去掉锯齿
					g.setColor(Color.red);
					p1 = li.get(0);
					p2 = li.get(1);
					
					point_XY[0] = p1.x;
					point_XY[1] = p1.y;
					point_XY[2] = p2.x;
					point_XY[3] = p2.y;
					
					g.fillOval(e.getX(), e.getY(), 2, 2);//画点
					g.drawLine(p1.x, p1.y, p2.x, p2.y);//画线
					System.out.println("绘制的点为:"+p1.x+" "+p1.y+","+p2.x+" "+p2.y);
					xy.add(point_XY);
					li.clear();
				} else {
					g = linePanel.getGraphics();
					g.setColor(Color.red);
					g.fillOval(e.getX(), e.getY(), 2, 2);
				}
			}

			@Override
			public void mousePressed(MouseEvent e) {
				// TODO Auto-generated method stub
				
			}

			@Override
			public void mouseReleased(MouseEvent e) {
				// TODO Auto-generated method stub
				
			}

			@Override
			public void mouseEntered(MouseEvent e) {
				// TODO Auto-generated method stub
				
			}

			@Override
			public void mouseExited(MouseEvent e) {
				// TODO Auto-generated method stub
				
			} 
		});

		this.button.removeActionListener(this);// 移除侦听事件
	}

}

解决方法：

在panel的paint()方法内重新绘制，通过list存储数据传过来，进行绘制。

public void paint(Graphics g) {
		    super.paint(g);
	            g.setColor(Color.red);
	            ((Graphics2D) g).setRenderingHint(RenderingHints.KEY_ANTIALIASING , RenderingHints.VALUE_ANTIALIAS_ON); //清除锯齿
	            
	            for(int i=0;i

这样问题就解决了，无论是最小化还是最大化，都不会消失！