运用Java做一个画板

首先给出文件结构

参考代码如下:

Graph.java

package Test.Package;

import javax.imageio.ImageIO;
import javax.swing.*;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.Serializable;
import java.net.URL;
import java.util.ArrayList;

abstract public class Graph implements Serializable{ //定义抽象类，并实现其序列化接口
    String type="line";
    Color color=Color.BLACK;  //线条颜色，默认为黑色
    float strokeWidth=1.0f; //线条粗细，默认为1.0f
    boolean fill=false;  //填充
    Point start=new Point(0,0);
    Point end=new Point(0,0);
    String string="";  // 插入字符串
    String fontName="宋体"; //字符串格式
    Integer fontSize=12; //字符串大小

    public Graph(){}

    public Graph(String type, Color color, float strokeWidth, boolean fill, Point start, Point end) {
        this.type = type;
        this.color = color;
        this.strokeWidth = strokeWidth;
        this.fill = fill;
        this.start = start;
        this.end = end;
    }// 构造方法

    void addPoint(){}

    abstract void draw(Graphics2D g);// 抽象方法

}

class Line extends Graph{

    public Line() {
        super();
    }

    public Line(String type, Color color, float strokeWidth, boolean fill, Point start, Point end) {
        super(type, color, strokeWidth, fill, start, end);
    }

    @Override
    void draw(Graphics2D g) {
        g.setPaint(color);
        g.setStroke(new BasicStroke(strokeWidth));
        g.drawLine(start.x,start.y,end.x,end.y);
    }
} //画线

class Rect extends Graph{
    public Rect() {
        super();
    }

    public Rect(String type, Color color, float strokeWidth, boolean fill, Point start, Point end) {
        super(type, color, strokeWidth, fill, start, end);
    }

    @Override
    void draw(Graphics2D g) {
        g.setPaint(color); // 设置颜色
        g.setStroke(new BasicStroke(strokeWidth));  //设置线条粗细
        int x=Math.min(start.x,end.x);
        int y=Math.min(start.y,end.y); // 得到起始坐标
        int width=Math.abs(start.x-end.x); // 宽
        int height=Math.abs(start.y-end.y); // 高
        if(fill)
            g.fillRect(x,y,width,height);
        else
            g.drawRect(x,y,width,height);
    }
}  //画矩形

class Loves extends Graph{
    public Loves() {
        super();
    }

    public Loves(String type, Color color, float strokeWidth, boolean fill, Point start, Point end) {
        super(type, color, strokeWidth, fill, start, end);
    }

    @Override
    void draw(Graphics2D g) {
        g.setColor(color);
        g.setStroke(new BasicStroke(strokeWidth));
        int x=Math.min(start.x,end.x);
        int y=Math.min(start.y,end.y); // 得到起始坐标
        int width = Math.abs(start.x - end.x); // 宽
        int height = Math.abs(start.y - end.y); // 高
        int[] xs=new int[360];
        int[] ys=new int[360];
        for(int i=0;i<360;i++){
            xs[i]= (int) (x-width/10*(28*Math.pow(Math.sin(i),3)));
            ys[i]= (int) (y-height/10*(20*Math.cos(i)-6*Math.cos(2*i)-3*Math.cos(3*i)-Math.cos(4*i) ));
        }
        if(fill){
            g.fillPolygon(xs,ys,360);
        }else{
            g.drawPolygon(xs,ys,360);
        }
    }
} // 画爱心

class Arc extends Graph{
    public Arc() {
        super();
    }

    public Arc(String type, Color color, float strokeWidth, boolean fill, Point start, Point end) {
        super(type, color, strokeWidth, fill, start, end);
    }

    @Override
    void draw(Graphics2D g) {
        g.setColor(color);
        g.setStroke(new BasicStroke(strokeWidth));
        int x = Math.min(start.x, end.x);
        int y = Math.min(start.y, end.y); // 得到起始坐标
        int width = Math.abs(start.x - end.x); // 宽
        int height = Math.abs(start.y - end.y); // 高
        g.drawArc(x,y,width,height,0,180);
    }
} // 画圆弧

class String2 extends Graph{

    public String2() {
        super();
    }

    public String2(String type, Color color, float strokeWidth, boolean fill, Point start, Point end) {
        super(type, color, strokeWidth, fill, start, end);
    }

    @Override
    void draw(Graphics2D g) {
        g.setColor(color);
        g.setFont(new Font(fontName,Font.BOLD,fontSize));
        g.drawString(string,start.x,start.y);
    }
}// 写入字符串

class Triangle extends Graph{
    Timer timer=null;
    public Triangle() {
        super();
    }

    public Triangle(String type, Color color, float strokeWidth, boolean fill, Point start, Point end) {
        super(type, color, strokeWidth, fill, start, end);
    }

    @Override
    void draw(Graphics2D g) {
        g.setColor(color);
        g.setStroke(new BasicStroke(strokeWidth));
        int x = Math.min(start.x, end.x);
        int y = Math.min(start.y, end.y); // 得到起始坐标
        int width = Math.abs(start.x - end.x); // 宽
        int height = Math.abs(start.y - end.y); // 高
        int[] xs = {x + width / 2, x, x + width};
        int[] ys = {y, y + height, y + height};
        if(fill){
            g.fillPolygon(xs,ys,3);
        }else{
            g.drawPolygon(xs, ys, 3); // 画三角形
        }
    }
}  // 三角形

class FivePoint extends Graph{
    public FivePoint() {
        super();
    }

    public FivePoint(String type, Color color, float strokeWidth, boolean fill, Point start, Point end) {
        super(type, color, strokeWidth, fill, start, end);
    }

    @Override
    void draw(Graphics2D g) {
        g.setColor(color);
        g.setStroke(new BasicStroke(strokeWidth));
        int x = Math.min(start.x, end.x);
        int y = Math.min(start.y, end.y); // 得到起始坐标
        int width = Math.abs(start.x - end.x); // 宽
        int height = Math.abs(start.y - end.y); // 高
        int xb= (int) (width/(2*Math.cos(Math.PI/5)));
        int yb= (int) (height/(1+Math.cos(Math.PI/5)));
        int zx=x+width/2;
        int zy=y+yb;
        // 根据五角星各个点的规律，得到五角星上相应的十个点的位置
        int[] xs={(int) (zx-xb*Math.cos(Math.PI/10)),(int) (zx+xb*Math.cos(Math.PI/10)),(int) (zx-xb*Math.sin(Math.PI/5)),zx,(int) (zx+xb*Math.sin(Math.PI/5))};
        int[] ys={(int) (zy-xb*Math.sin(Math.PI/10)),(int) (zy-xb*Math.sin(Math.PI/10)),(int) (zy+xb*Math.cos(Math.PI/5)),zy-yb,(int) (zy+xb*Math.cos(Math.PI/5))};
        int[] xs1={xs[0],xs[0]+(xs[1]-xs[0])/3,xs[3],xs[0]+2*(xs[1]-xs[0])/3,xs[1]
                ,xs[3]+2*(xs[4]-xs[3])/3,xs[4],xs[3],xs[2],xs[3]-2*(xs[3]-xs[2])/3};
        int[] ys1={ys[0],ys[0],ys[3],ys[0],ys[1],ys[3]+2*(ys[4]-ys[3])/3
                ,ys[4],ys[0]+2*(ys[4]-ys[0])/3,ys[2],ys[3]+2*(ys[2]-ys[3])/3};

        if(fill){
            g.fillPolygon(xs1,ys1,10);
        }else{
            g.drawPolygon(xs1,ys1,10);
        }
    }
} //五角星

class Oval extends Graph{
    public Oval() {
        super();
    }

    public Oval(String type, Color color, float strokeWidth, boolean fill, Point start, Point end) {
        super(type, color, strokeWidth, fill, start, end);
    }

    @Override
    void draw(Graphics2D g) {
        g.setPaint(color);
        g.setStroke(new BasicStroke(strokeWidth));
        int x=Math.min(start.x,end.x);
        int y=Math.min(start.y,end.y);
        int width=Math.abs(start.x-end.x);
        int height=Math.abs(start.y-end.y);
        if(fill)
            g.fillOval(x,y,width,height);
        else
            g.drawOval(x,y,width,height);
    }
} //画椭圆

class Pencil extends Graph{
    ArrayList<Point> points=new ArrayList<>();

    public Pencil() {
        super();
    }

    public Pencil(String type, Color color, float strokeWidth, boolean fill, Point start, Point end) {
        super(type, color, strokeWidth, fill, start, end);
    }

    @Override
    void draw(Graphics2D g) {
        g.setPaint(color);
        g.setStroke(new BasicStroke(strokeWidth));
        if(points.size()>1){
            Point s=points.get(0);
            for (Point e:points) {
                g.drawLine(s.x,s.y,e.x,e.y);
                s=e;
            }
        }
    }

    @Override
    void addPoint() {
        points.add(end);
    }
} //画笔

class Rubber extends Pencil{
    public Rubber() {
        super();
    }

    public Rubber(String type, Color color, float strokeWidth, boolean fill, Point start, Point end) {
        super(type, Color.WHITE, 36.0f, false, start, end);
    }

    @Override
    void draw(Graphics2D g) {
        super.draw(g);
    }
}//橡皮

class Image extends Graph{
    BufferedImage Image=null;

    public Image() {
        super();
    }

    public Image(String type, Color color, float strokeWidth, boolean fill, Point start, Point end) {
        super(type, color, strokeWidth, fill, start, end);
    }

    public void setImage(){
        URL url=getClass().getResource("/images/12.png"); //获取钟面图像文件的url
        try {
            Image= ImageIO.read(url); //载入图像
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @Override
    void draw(Graphics2D g) {
        g.setPaint(color);
        g.setStroke(new BasicStroke(strokeWidth));
        int x=Math.min(start.x,end.x);
        int y=Math.min(start.y,end.y);
        int width=Math.abs(start.x-end.x);
        int height=Math.abs(start.y-end.y);
        setImage();
        g.drawImage(Image,x,y,width,height,null);  // 绘制图片
    }
}// 插入图片

class Image2 extends Graph{
    public Image2() {
        super();
    }

    public Image2(String type, Color color, float strokeWidth, boolean fill, Point start, Point end) {
        super(type, color, strokeWidth, fill, start, end);
    }

    @Override
    void draw(Graphics2D g) {

    }
} /* 为Image类定义的类，如果直接保存具有Image对象的文件，会提示无法保存，
    如果将Image对象转换成Image2对象之后就可以实现保存功能了*/

Main.java

package Test.Package;

import javax.swing.*;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.net.URL;
import java.util.ArrayList;

public class Main {
    public static void main(String[] args) {
        FrmMain frmMain=new FrmMain();
        frmMain.setVisible(true);
    }
}

class FrmMain extends JFrame{
    String[] buttonStrings={"line","rect","oval","fivepoint","triangle","loves","pencil","color","string","arc","rubber","image"};
    String[] tipStrings={"绘制直线","绘制矩形","绘制椭圆","绘制五角星","绘制三角形","绘制爱心","自由绘制","选择颜色","输入文字","圆弧","橡皮","贴纸"};

    JMenuBar menuBar;
    JToolBar toolBar;
    JButton[] buttons; // 按钮数组
    JLabel stausBar;
    JComboBox cbxFont;   // 字体下拉框
    JComboBox cbxFontSize; // 字体大小下拉框
    String fontName="宋体"; // 默认字体为宋体
    Integer fontSize=12; //字体默认大小为12
    JPanel fontPanel;  // 字体面板
    JTextField jtextField; // 文本框
    JSlider slider;
    JCheckBox fillCheckBox;
    DrawPanel drawPanel; // 画板

    String type="line";
    Color color=Color.BLACK;
    float strokeWidth=1.0f; // 线条粗细默认为1.0
    boolean fill=false;  // 默认为不填充
    Point start=new Point(0,0);
    Point end=new Point(0,0);
    Graph graph;
    ArrayList<Graph> graphList=new ArrayList<>();

    public FrmMain(){
        super("我的画板");

        setBounds(400,200,1400,900);  // 设置窗口的大小为800，600
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        ButtonListener buttonListener=new ButtonListener(); // 按钮监控器对象

        // 菜单栏
        menuBar=new JMenuBar();
        setJMenuBar(menuBar);
        JMenu fileMenu=new JMenu("文件");
        JMenu editMenu=new JMenu("编辑");
        menuBar.add(fileMenu);
        menuBar.add(editMenu);
        JMenuItem newItem=new JMenuItem("新建");
        JMenuItem saveItem=new JMenuItem("保存");
        JMenuItem openItem=new JMenuItem("打开");
        JMenuItem exitItem=new JMenuItem("退出");
        newItem.setActionCommand("new");
        saveItem.setActionCommand("save");
        openItem.setActionCommand("open");
        exitItem.setActionCommand("exit");
        fileMenu.add(newItem);
        fileMenu.add(saveItem);
        fileMenu.add(openItem);
        fileMenu.addSeparator();  //为菜单项之间添加一个分割线
        fileMenu.add(exitItem);
        JMenuItem undoItem=new JMenuItem("撤销");
        undoItem.setActionCommand("undo");
        editMenu.add(undoItem);

        newItem.addActionListener(buttonListener);
        saveItem.addActionListener(buttonListener);
        openItem.addActionListener(buttonListener);
        exitItem.addActionListener(buttonListener);
        undoItem.addActionListener(buttonListener);

        // 工具栏 ，默认为水平布局
        toolBar=new JToolBar(JToolBar.HORIZONTAL);
        add(toolBar,BorderLayout.NORTH);  // 将工具栏添加到窗口中
        buttons=new JButton[tipStrings.length];
        for (int i=0;i<buttons.length;i++){
            URL url=getClass().getResource("/images/"+buttonStrings[i]+".png");
            ImageIcon imageIcon=new ImageIcon(url);
            buttons[i]=new JButton(imageIcon);  // 创建包含图标的按钮

            buttons[i].setToolTipText(tipStrings[i]);   //用来设置鼠标停在按钮上提示的信息
            buttons[i].setActionCommand(buttonStrings[i]);
            toolBar.add(buttons[i]);
            buttons[i].addActionListener(buttonListener);  // 为按钮添加监听器
        }

        fillCheckBox=new JCheckBox("填充"); // 复选框
        toolBar.add(fillCheckBox);
        fillCheckBox.addChangeListener(new ChangeListener() {
            @Override
            public void stateChanged(ChangeEvent e) {
                fill=fillCheckBox.isSelected(); // 返回布尔类型
            }
        });  // 为复选框添加监听器

        fontPanel=new JPanel();
        cbxFont=new JComboBox(); // 字体
        cbxFontSize=new JComboBox(); // 字体大小

        fontPanel.add(cbxFont);
        fontPanel.add(cbxFontSize);
        toolBar.add(fontPanel);

        GraphicsEnvironment ge=GraphicsEnvironment.getLocalGraphicsEnvironment();
        String[] fontList=ge.getAvailableFontFamilyNames();  // 获得系统的字体数组
        for(int i=0;i<fontList.length;i++)
            cbxFont.addItem(fontList[i]);  // 添加字体名称
        cbxFont.setSelectedIndex(31);

        for(int i=9;i<=72;i++)  // 添加字体大小
            cbxFontSize.addItem(new Integer(i).toString());
        cbxFontSize.setSelectedIndex(3);

        cbxFont.addItemListener(new ItemListener() {
            @Override
            public void itemStateChanged(ItemEvent e) {
                fontName= (String) cbxFont.getSelectedItem();
            }
        }); // 为下拉框设置监听器

        cbxFontSize.addItemListener(new ItemListener() {
            @Override
            public void itemStateChanged(ItemEvent e) {
                fontSize= Integer.parseInt((String) cbxFontSize.getSelectedItem());
            }
        });

        jtextField=new JTextField();  // 文本框
        jtextField.setFont(new Font("宋体",Font.BOLD,20));
        toolBar.add(jtextField);

        // 滑动条
        slider=new JSlider(1,20,1);
        slider.setMajorTickSpacing(1);
        slider.setPaintTicks(true);
        slider.setSnapToTicks(true);
        slider.setSize(200,30);
        slider.addChangeListener(new ChangeListener() {
            @Override
            public void stateChanged(ChangeEvent e) {
                strokeWidth=slider.getValue();
            }
        });  // 为滚动条添加监听器

        JPanel panel=new JPanel();
        panel.add(new JLabel("粗细"));
        panel.add(slider);  // 将组件slider添加到一个面板当中
        toolBar.add(panel); // 将这个面板添加到工具栏当中

        // 状态栏
        stausBar=new JLabel();
        stausBar.setText("欢迎使用画板");
        add(stausBar,BorderLayout.SOUTH);

        drawPanel=new DrawPanel();  // 画板
        add(drawPanel,BorderLayout.CENTER);

        try {
            String IfClassName="com.sun.java.swing.plaf.windows.WindowsClassicLookAndFeel";
            UIManager.setLookAndFeel(IfClassName);
            SwingUtilities.updateComponentTreeUI(this);
        } catch (Exception e) {
            e.printStackTrace();
        } // 设置图形界面风格
    }
    // 鼠标点击监听器类
    class MouseA extends MouseAdapter{
        @Override
        public void mousePressed(MouseEvent e) {
            stausBar.setText("鼠标按下["+e.getX()+","+e.getY()+"]");
            start=e.getPoint();
            end=e.getPoint();
            createNewGraph();

            if(type.equals("string") && e.getClickCount()==2){
                graph.string=jtextField.getText();
            }  // 如果点击按钮之后，type="etring",并且点击次数为2,那么将文本框中的内容赋值给graph对象中的变量string
            drawPanel.repaint();  // 重绘面板
        }

        @Override
        public void mouseReleased(MouseEvent e) {
            stausBar.setText("鼠标释放["+e.getX()+","+e.getY()+"]");

            graph.end=e.getPoint();

            drawPanel.repaint();
        }

        @Override
        public void mouseExited(MouseEvent e) {
            stausBar.setText("欢迎使用画板");
        }
    }

    class MouseB implements MouseMotionListener{

        @Override
        public void mouseDragged(MouseEvent e) {
            stausBar.setText("鼠标拖动["+e.getX()+","+e.getY()+"]");

            graph.end=e.getPoint();

            if(type.equals("pencil") || type.equals("rubber"))
                graph.addPoint();

            drawPanel.repaint();
        }

        @Override
        public void mouseMoved(MouseEvent e) {
            stausBar.setText("鼠标移动["+e.getX()+","+e.getY()+"]");
        }
    }

    class ButtonListener implements ActionListener{

        @Override
        public void actionPerformed(ActionEvent e) {
            String comStr=e.getActionCommand();
            switch (comStr){
                case "line":
                case "rect":
                case "oval":
                case "fivepoint":
                case "triangle":
                case "loves":
                case "pencil":
                case "string":
                case "rubber":
                case "arc":
                case "image":
                    type=comStr;
                    break;
                case "color":
                    Color selectedColor=JColorChooser.showDialog(FrmMain.this,"选择颜色",color);
                    if(selectedColor!=null)
                        color=selectedColor;
                    break;
                case "new":
                    graphList.clear();
                    drawPanel.repaint();
                    break;
                case "save":
                    saveFile();
                    break;
                case "open":
                    loadFile();
                    break;
                case "exit":
                    System.exit(0);
                case "undo":  // 防止撤销报错
                    try{
                        graphList.remove(graphList.size()-1);
                        drawPanel.repaint();
                    }catch (Exception e2){
                        JOptionPane.showMessageDialog(FrmMain.this,"当前没有任何可以撤销的！");
                    }
                default:
                    break;
            }
        }
    }
   // 绘图面板类
    class DrawPanel extends JPanel{
        public DrawPanel() {
            setCursor(Cursor.getPredefinedCursor(Cursor.CROSSHAIR_CURSOR));  // 设置光标的形状，这里为十字光标
            setBackground(Color.WHITE);  // 设置面板的背景颜色为白色

            addMouseListener(new MouseA());
            addMouseMotionListener(new MouseB());
        }

       public Cursor createCursor(String fileName) {
           java.awt.Image cursor = Toolkit.getDefaultToolkit().createImage(Toolkit.class.getResource(fileName));
           return Toolkit.getDefaultToolkit().createCustomCursor(cursor, new Point(0, 27), "mycursor");
       }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            for (Graph graph:graphList){
                graph.draw((Graphics2D)g);
            }
        }
    }

    void createNewGraph(){
        switch (type){
            case "line":
                graph=new Line(type,color,strokeWidth,fill,start,end);
                break;
            case "rect":
                graph=new Rect(type,color,strokeWidth,fill,start,end);
                break;
            case "oval":
                graph=new Oval(type,color,strokeWidth,fill,start,end);
                break;
            case "fivepoint":
                graph=new FivePoint(type,color,strokeWidth,fill,start,end);
                break;
            case "triangle":
                graph=new Triangle(type,color,strokeWidth,fill,start,end);
                break;
            case "loves":
                graph=new Loves(type,color,strokeWidth,fill,start,end);
                break;
            case "pencil":
                graph=new Pencil(type,color,strokeWidth,fill,start,end);
                break;
            case "string":
                graph=new String2(type,color,strokeWidth,fill,start,end);
                graph.fontName=fontName;
                graph.fontSize=fontSize;
                break;
            case "arc":
                graph=new Arc(type,color,strokeWidth,fill,start,end);
                break;
            case "rubber":
                graph=new Rubber(type,color,strokeWidth,fill,start,end);
                break;
            case "image":
                graph=new Image(type,color,strokeWidth,fill,start,end);
            default:
                break;
        }
        switch (type){  /*设置光标形状
        如果绘制的type为line(线)、rect(矩形)、oval(椭圆)、fivepoint(五角星)、triangle(三角形)、loves(爱心)、image(图片，这里为贴纸)、arc(圆弧),那么光标形状为十字符号
        如果绘制的type为pencil(画笔),那么光标形状为一支画笔（使用图片）
        如果需要添加注解，那么光标形状为文字光标类型
        如果type为rubber（橡皮）,那么光标形状为一个正方形（使用图片）
        */
            case "line":
            case "rect":
            case "oval":
            case "fivepoint":
            case "triangle":
            case "loves":
            case "image":
            case "arc":
                drawPanel.setCursor(Cursor.getPredefinedCursor(Cursor.CROSSHAIR_CURSOR));
                break;
            case "pencil":
                drawPanel.setCursor(drawPanel.createCursor("/images/pencil2.png"));
                break;
            case "string":
                drawPanel.setCursor(Cursor.getPredefinedCursor(Cursor.TEXT_CURSOR));
                break;
            case "rubber":
                drawPanel.setCursor(drawPanel.createCursor("/images/rubber2.png"));
            default:
                break;
        }
        graphList.add(graph);
    }

    void saveFile(){
        ArrayList<Graph> graphList2=new ArrayList<>();
        for(int i=0;i<graphList.size();i++){
            Graph graph1=graphList.get(i);
            String string=String.valueOf(graph1.getClass());
            int index=string.lastIndexOf(".")+1;
            if(string.substring(index).equals("Image")){
                graph1=new Image2(graph1.type,graph1.color,graph1.strokeWidth,graph1.fill,graph1.start,graph1.end);
            }  // 这里如果直接将Image对象写到文件中，会报错，所以将它转换成Image2对象之后再写入
            graphList2.add(graph1);
        }
        ObjectOutputStream output;

        JFileChooser fileChooser=new JFileChooser();
        fileChooser.setFileSelectionMode(JFileChooser.FILES_ONLY);
        int result=fileChooser.showSaveDialog(this);
        if(result==JFileChooser.CANCEL_OPTION)
            return;
        File file=fileChooser.getSelectedFile();
        file.canWrite();
        file.delete();

        try {
            output=new ObjectOutputStream(new FileOutputStream(file));
            output.writeObject(graphList2);
            output.close();
        } catch (Exception e) {
            JOptionPane.showMessageDialog(this,"保存文件出错！");
        }
    } // 保存文件

    void loadFile(){
        ArrayList<Graph> graphList2=null;
        ObjectInputStream input;

        JFileChooser fileChooser=new JFileChooser();
        fileChooser.setFileSelectionMode(JFileChooser.FILES_ONLY);
        int result=fileChooser.showOpenDialog(this);
        if(result==JFileChooser.CANCEL_OPTION)
            return;
        File file=fileChooser.getSelectedFile();
        file.canRead();

        try {
            input=new ObjectInputStream(new FileInputStream(file));
            graphList2=(ArrayList<Graph>)input.readObject();
            graphList.clear();
            for (int i=0;i<graphList2.size();i++){
                Graph graph1=graphList2.get(i);
                String string=String.valueOf(graph1.getClass());
                int index=string.lastIndexOf(".")+1;
                if(string.substring(index).equals("Image2")){
                    graph1=new Image(graph1.type,graph1.color,graph1.strokeWidth,graph1.fill,graph1.start,graph1.end);
                } // 如果读取的对象中有Image2对象，那么将它转换成Image对象
                graphList.add(graph1);
            }
            drawPanel.repaint();
            input.close();
        } catch (Exception e) {
            JOptionPane.showMessageDialog(this,"打开文件出错！");
        }  // 打开文件
    }
}

运行结果如下:

讲明一点: 直接复制代码可能不会运行成功，需要在src下新建文件夹images，然后再这个文件夹下面放一些图片，当然图片命名请参考代码中的图片命名，另外，图片的大小也需要重新设置一下。还有保存好的图片要用这个代码程序打开，否则不会显示，命名不需要后缀名。