b0f5b0916aa6001c12d3a6ace67d4745

用JAVA语言编制一个画图板

   public void mouseExited(MouseEvent e)
   {statusBar.setText("     鼠标离开 @:[" + e.getX() +
                              ", " + e.getY() + "]"); }
 }

//鼠标事件mouseB类继承了MouseMotionAdapter，用来完成鼠标拖动和鼠标移动时的相应操作
 class mouseB extends MouseMotionAdapter
 {
  public void mouseDragged(MouseEvent e)
  {statusBar.setText("     拖拉鼠标 @:[" + e.getX() +
                              ", " + e.getY() + "]");
   if(currentChoice==3||currentChoice==13)
   {
    itemList[index-1].x1=itemList[index].x2=itemList[index].x1=e.getX();
    itemList[index-1].y1=itemList[index].y2=itemList[index].y1=e.getY();
    index++;
    createNewItem();
   }
   else
    {
     itemList[index].x2=e.getX();
     itemList[index].y2=e.getY();
    }
   repaint();
   }
  public void mouseMoved(MouseEvent e)
   {statusBar.setText("    移动鼠标 @:[" + e.getX() +
                              ", " + e.getY() + "]");}
  }

//选择字体风格时候用到的事件侦听器类，加入到字体风格的选择框中
private class checkBoxHandler implements ItemListener
{ public void itemStateChanged(ItemEvent e)
  {
   if(e.getSource()==bold)
     if(e.getStateChange()==ItemEvent.SELECTED)
        f1=Font.BOLD;
     else
        f1=Font.PLAIN;
   if(e.getSource()==italic)
     if(e.getStateChange()==ItemEvent.SELECTED)
        f2=Font.ITALIC;
     else
        f2=Font.PLAIN;
  }
 }

//画图面板类，用来画图
 class DrawPanel extends JPanel
 { public DrawPanel()
   {
    setCursor(Cursor.getPredefinedCursor(Cursor.CROSSHAIR_CURSOR));
    setBackground(Color.white);
    addMouseListener(new mouseA());
    addMouseMotionListener(new mouseB());
   }
   public void paintComponent(Graphics g)
    {
     super.paintComponent(g);
     Graphics2D g2d=(Graphics2D)g;	//定义画笔
     int j=0;
     while (j<=index)
      {draw(g2d,itemList[j]); j++;}
    }
   void draw(Graphics2D g2d,drawings i)
    {i.draw(g2d);}//将画笔传入到各个子类中，用来完成各自的绘图
 }

//新建一个画图基本单元对象的程序段
 void createNewItem()
  { if(currentChoice==14)//进行相应的游标设置
      drawingArea.setCursor(Cursor.getPredefinedCursor(Cursor.TEXT_CURSOR));
    else
      drawingArea.setCursor(Cursor.getPredefinedCursor(Cursor.CROSSHAIR_CURSOR));
    switch (currentChoice)
    {
      case 3:
        itemList[index]=new Pencil();
        break;
      case 4:
        itemList[index]=new Line();
        break;
      case 5:
        itemList[index]=new Rect();
        break;
      case 6:
        itemList[index]=new fillRect();
        break;
      case 7:
        itemList[index]=new Oval();
        break;
      case 8:
        itemList[index]=new fillOval();
        break;
      case 9:
        itemList[index]=new Circle();
        break;
      case 10:
        itemList[index]=new fillCircle();
        break;
      case 11:
        itemList[index]=new RoundRect();
        break;
      case 12:
        itemList[index]=new fillRoundRect();
        break;
      case 13:
        itemList[index]=new Rubber();
        break;
      case 14:
        itemList[index]=new Word();
        break;
    }
    itemList[index].type=currentChoice;
    itemList[index].R=R;
    itemList[index].G=G;
    itemList[index].B=B;
    itemList[index].stroke=stroke;
  }

//选择当前颜色程序段
public void chooseColor()
 {
    color=JColorChooser.showDialog(MiniDrawPad.this, "选择颜色",color);
    R=color.getRed();
    G=color.getGreen();
    B=color.getBlue();
    itemList[index].R=R;
    itemList[index].G=G;
    itemList[index].B=B;
  }

//选择当前线条粗细程序段
public void setStroke()
 {
  String input;
  input=JOptionPane.showInputDialog("请输入线条粗细值! ( >0 )");
  stroke=Float.parseFloat(input);
  itemList[index].stroke=stroke;
  }

//保存图形文件程序段
 public void saveFile()
 {
    JFileChooser fileChooser=new JFileChooser();
    fileChooser.setFileSelectionMode(JFileChooser.FILES_ONLY);
    int result =fileChooser.showSaveDialog(this);
    if(result==JFileChooser.CANCEL_OPTION)  return ;
    File fileName=fileChooser.getSelectedFile();
    fileName.canWrite();

    if (fileName==null||fileName.getName().equals(""))
      JOptionPane.showMessageDialog(fileChooser,"输入文件名字",
       "输入文件名字", JOptionPane.ERROR_MESSAGE);
    else{
      try 
      {fileName.delete();
       FileOutputStream fos=new FileOutputStream(fileName);

       output=new ObjectOutputStream(fos);
       drawings record;
       output.writeInt( index );

       for(int i=0;i< index ;i++)
       { drawings p= itemList[ i ] ;
         output.writeObject(p);
         output.flush();    //将所有图形信息强制转换成父类线性化存储到文件中
       }
       output.close();
       fos.close();
      }catch(IOException ioe)
       { ioe.printStackTrace(); }
    }
  }

//打开一个图形文件程序段
 public void loadFile()
 {
    JFileChooser fileChooser=new JFileChooser();
    fileChooser.setFileSelectionMode(JFileChooser.FILES_ONLY);
    int result =fileChooser.showOpenDialog(this);
    if(result==JFileChooser.CANCEL_OPTION)  return ;
    File fileName=fileChooser.getSelectedFile();
    fileName.canRead();
    if (fileName==null||fileName.getName().equals(""))
       JOptionPane.showMessageDialog(fileChooser,"输入文件名字",
            "输入文件名字", JOptionPane.ERROR_MESSAGE);
    else {
      try 
       { FileInputStream fis=new FileInputStream(fileName);
         input=new ObjectInputStream(fis);
         drawings inputRecord;
         int countNumber=0;
         countNumber=input.readInt();

         for(index=0;index< countNumber ;index++)
          {inputRecord=(drawings)input.readObject();
            itemList[ index ] = inputRecord ;
          }
         createNewItem();
         input.close();
         repaint();
       }catch(EOFException endofFileException){
            JOptionPane.showMessageDialog(this,"在文件中没有更多记录",
                           "类不能发现",JOptionPane.ERROR_MESSAGE );
          }
          catch(ClassNotFoundException classNotFoundException){
            JOptionPane.showMessageDialog(this,"不能创建新物体",
                           "文件结束",JOptionPane.ERROR_MESSAGE );
          }
          catch (IOException ioException){
            JOptionPane.showMessageDialog(this,"在读取文件过程出现错误",
                           "读取错误",JOptionPane.ERROR_MESSAGE );
            }
    }
  }

//新建一个文件程序段
 public void newFile()
 {
  index=0;
  currentChoice=3;
  color=Color.black;
  stroke=1.0f;
  createNewItem();
  repaint();//将有关值设置为初始状态，并且重画
 }

//#################################################################
//主函数段
 public static void main(String args[])
  {try 
    {UIManager.setLookAndFeel( UIManager.getSystemLookAndFeelClassName());
      } catch ( Exception e ) {}//将界面设置为当前windows风格

   MiniDrawPad newPad=new MiniDrawPad();
   newPad.addWindowListener(
     new WindowAdapter(){
      public void windowClosing(WindowEvent e)
       {System.exit(0);}});
  }
}

//定义画图的基本图形单元
class drawings implements Serializable//父类，基本图形单元，用到串行化接口，保存时所用
 {
  int x1,y1,x2,y2;	//定义坐标属性
  int R,G,B;		//定义色彩属性
  float stroke;		//定义线条粗细属性
  int type;		    //定义字体属性
  String s1;
  String s2;		//定义字体风格属性
  void draw(Graphics2D g2d){};//定义绘图函数
 }

//*******************************************************************
// 定义各种基本图形单元的子类，都继承自父类drawings。

 class Line extends drawings //直线类
 { void draw(Graphics2D g2d)
    {g2d.setPaint(new Color(R,G,B));
     g2d.setStroke(new BasicStroke(stroke,
         BasicStroke.CAP_ROUND,BasicStroke.JOIN_BEVEL));
     g2d.drawLine(x1,y1,x2,y2);
    }
 }

 class Rect extends drawings//矩形类
 {void draw(Graphics2D g2d)
  {g2d.setPaint(new Color(R,G,B));
   g2d.setStroke(new BasicStroke(stroke));
   g2d.drawRect(Math.min(x1,x2),Math.min(y1,y2),
          Math.abs(x1-x2),Math.abs(y1-y2));
  }
 }

 class fillRect extends drawings//实心矩形类
 {void draw(Graphics2D g2d)
  {g2d.setPaint(new Color(R,G,B));
   g2d.setStroke(new BasicStroke(stroke));
   g2d.fillRect(Math.min(x1,x2),Math.min(y1,y2),
              Math.abs(x1-x2),Math.abs(y1-y2));
  }
 }

 class Oval extends drawings//椭圆类
  {void draw(Graphics2D g2d)
    {g2d.setPaint(new Color(R,G,B));
     g2d.setStroke(new BasicStroke(stroke));
     g2d.drawOval(Math.min(x1,x2),Math.min(y1,y2),
                  Math.abs(x1-x2),Math.abs(y1-y2));
    }
  }

 class fillOval extends drawings//实心椭圆
 {void draw(Graphics2D g2d)
  {g2d.setPaint(new Color(R,G,B));
   g2d.setStroke(new BasicStroke(stroke));
   g2d.fillOval(Math.min(x1,x2),Math.min(y1,y2),
                Math.abs(x1-x2),Math.abs(y1-y2));
  }
 }

 class Circle extends drawings//圆类
 {void draw(Graphics2D g2d)
   {g2d.setPaint(new Color(R,G,B));
    g2d.setStroke(new BasicStroke(stroke));
    g2d.drawOval(Math.min(x1,x2),Math.min(y1,y2),
               Math.max(Math.abs(x1-x2),Math.abs(y1-y2)),
               Math.max(Math.abs(x1-x2),Math.abs(y1-y2))
               );
   }
 }

 class fillCircle extends drawings//实心圆
 {void draw(Graphics2D g2d)
  {g2d.setPaint(new Color(R,G,B));
   g2d.setStroke(new BasicStroke(stroke));
   g2d.fillOval(Math.min(x1,x2),Math.min(y1,y2),
               Math.max(Math.abs(x1-x2),Math.abs(y1-y2)),
               Math.max(Math.abs(x1-x2),Math.abs(y1-y2))
               );
  }
 }

 class RoundRect extends drawings//圆角矩形类
 {
  void draw(Graphics2D g2d)
  {g2d.setPaint(new Color(R,G,B));
   g2d.setStroke(new BasicStroke(stroke));
   g2d.drawRoundRect(Math.min(x1,x2),Math.min(y1,y2),
                   Math.abs(x1-x2),Math.abs(y1-y2), 50,35);
   }
 }

 class fillRoundRect extends drawings//实心圆角矩形类
 {void draw(Graphics2D g2d)
  {g2d.setPaint(new Color(R,G,B));
   g2d.setStroke(new BasicStroke(stroke));
   g2d.fillRoundRect(Math.min(x1,x2),Math.min(y1,y2),
                   Math.abs(x1-x2),Math.abs(y1-y2),50,35);
  }
 }

 class Pencil extends drawings//随笔画类
 {void draw(Graphics2D g2d)
  {g2d.setPaint(new Color(R,G,B));
   g2d.setStroke(new BasicStroke(stroke,
          BasicStroke.CAP_ROUND,BasicStroke.JOIN_BEVEL));
   g2d.drawLine(x1,y1,x2,y2);
  }
 }

 class Rubber extends drawings//橡皮擦类
 {void draw(Graphics2D g2d)
  {g2d.setPaint(new Color(255,255,255));
   g2d.setStroke(new BasicStroke(stroke+4,
          BasicStroke.CAP_ROUND,BasicStroke.JOIN_BEVEL));
   g2d.drawLine(x1,y1,x2,y2);
  }
 }

 class Word extends drawings//输入文字类
 {void draw(Graphics2D g2d)
   {g2d.setPaint(new Color(R,G,B));
    g2d.setFont(new Font(s2,x2+y2,((int)stroke)*18));
    if (s1!= null )  g2d.drawString(s1,x1,y1);
   }
 }
//*********************************************************************