java画板小demo

用java写的一个画板demo 是Java课程的一个作业，比较简单直接贴代码，有不完善的地方，但是因为对swing编程没什么兴趣所以暂时不想改了
MyPanel.java
import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Panel;
import java.awt.Point;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionAdapter;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;
import java.util.Vector;

public class MyPanel extends Panel{

    /**
     *
     */
    private static final long serialVersionUID = 1L;

    enum DrawType
    {
        FreeDom,
        Line,
        Ellipse,
        Rectangle
    }

    private Vector<Vector<Point>> FreedomDatas = new Vector<Vector<Point>>(); //freeDom时使用
    private Vector<Vector<Point>> lineDatas = new Vector<Vector<Point>>(); //Line时使用
    private Vector<Vector<Point>> ellipseDatas = new Vector<Vector<Point>>();
    private Vector<Vector<Point>> rectangleDatas = new Vector<Vector<Point>>();

    private Color lineColor = Color.blue;
    private int lineWidth = 5;
    private DrawType drawType = DrawType.FreeDom;

    private Vector<Vector<Vector<Point>>> allWriteDatas = new Vector<Vector<Vector<Point>>>();
    private Vector<Vector<Vector<Point>>> allReadDatas = new Vector<Vector<Vector<Point>>>();

    public MyPanel()
    {
        addMouseListener(new MouseAdapter()
        {
            public void mousePressed(MouseEvent e)
            {
                switch(drawType)
                {
                    case FreeDom:
                        Point p = new Point(e.getX(),e.getY());
                        Vector<Point> newLine = new Vector<Point>();
                        newLine.add(p);
                        FreedomDatas.add(newLine);
                        break;
                    case Line:
                        //画直线
                        Point prePoint = new Point(e.getX(),e.getY());
                        Vector<Point> newl = new Vector<Point>();
                        newl.add(prePoint);
                        lineDatas.add(newl);
                        break;
                    case Ellipse:
                        //画椭圆
                        Point newPoint = new Point(e.getX(),e.getY());
                        Vector<Point> newp = new Vector<Point>();
                        newp.add(newPoint);
                        ellipseDatas.add(newp);
                        break;
                    case Rectangle:
                        //画矩形
                        Point nPoint = new Point(e.getX(),e.getY());
                        Vector<Point> newn = new Vector<Point>();
                        newn.add(nPoint);
                        rectangleDatas.add(newn);
                        break;

补充：软件开发 , Java ,