我必须开发一个本地用户和远程用户都应该是的白板应用程序，able to draw simultaneously这可能吗？如果可能，那么任何逻辑？
我已经开发了一个代码，但是当远程用户开始绘制我正在绘制的形状被他的形状和坐标替换时，我无法做到这一点。仅当两者同时绘制时才会出现此问题。
有什么想法吗？
这是我的代码
class Paper extends JPanel implements MouseListener,MouseMotionListener,ActionListener
{
static BufferedImage image;
int bpressed;
Color color;
Point start;
Point end;
Point mp;
Button elipse=new Button("elipse");
Button rectangle=new Button("rect");
Button line=new Button("line");
Button empty=new Button("");
JButton save=new JButton("Save");
JButton erase=new JButton("Erase");
String selected;
int ex,ey;//eraser
DatagramSocket dataSocket;
JButton button = new JButton("test");
Client client;
Point p=new Point();
int w,h;
public Paper(DatagramSocket dataSocket)
{
this.dataSocket=dataSocket;
client=new Client(dataSocket);
System.out.println("paper");
setBackground(Color.white);
addMouseListener(this);
addMouseMotionListener(this);
color = Color.black;
setBorder(BorderFactory.createLineBorder(Color.black));
//save.setPreferredSize(new Dimension(100,20));
save.setMaximumSize(new Dimension(75,27));
erase.setMaximumSize(new Dimension(75,27));
}
public void paintComponent(Graphics g)
{
try
{
g.drawImage(image, 0, 0, this);
Graphics2D g2 = (Graphics2D)g;
g2.setPaint(Color.black);
if(selected==("elipse"))
g2.drawOval(start.x, start.y,(end.x-start.x),(end.y-start.y));
else if(selected==("rect"))
g2.drawRect(start.x, start.y, (end.x-start.x),(end.y-start.y));
else if(selected==("line"))
g2.drawLine(start.x,start.y,end.x,end.y);
}
catch(Exception e)
{}
}
//Function to draw the shape on image
public void draw()
{
Graphics2D g2 = image.createGraphics();
g2.setPaint(color);
if(selected=="line")
g2.drawLine(start.x, start.y, end.x, end.y);
if(selected=="elipse")
g2.drawOval(start.x, start.y, (end.x-start.x),(end.y-start.y));
if(selected=="rect")
g2.drawRect(start.x, start.y, (end.x-start.x),(end.y-start.y));
repaint();
g2.dispose();
start=null;
}
//To add the point to the board which is broadcasted by the server
public synchronized void addPoint(Point ps,String varname,String shape,String event)
{
try
{
if(end==null)
end = new Point();
if(start==null)
start = new Point();
if(shape.equals("elipse"))
selected="elipse";
else if(shape.equals("line"))
selected="line";
else if(shape.equals("rect"))
selected="rect";
else if(shape.equals("erase"))
{
selected="erase";
erase();
}
if(end!=null && start!=null)
{
if(varname.equals("end"))
end=ps;
if(varname.equals("mp"))
mp=ps;
if(varname.equals("start"))
start=ps;
if(event.equals("drag"))
repaint();
else if(event.equals("release"))
draw();
}
}
catch(Exception e)
{
e.printStackTrace();
}
}
//To set the size of the image
public void setWidth(int x,int y)
{
System.out.println("("+x+","+y+")");
w=x;
h=y;
image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
Graphics2D g2 = image.createGraphics();
g2.setPaint(Color.white);
g2.fillRect(0,0,w,h);
g2.dispose();
}
//Function which provides the erase functionality
public void erase()
{
Graphics2D pic=(Graphics2D) image.getGraphics();
pic.setPaint(Color.white);
pic.fillRect(start.x, start.y, 10, 10);
}
//Function to add buttons into the panel, calling this function returns a panel
public JPanel addButtons()
{
JPanel buttonpanel=new JPanel();
JPanel row1=new JPanel();
JPanel row2=new JPanel();
JPanel row3=new JPanel();
JPanel row4=new JPanel();
buttonpanel.setPreferredSize(new Dimension(80,80));
//buttonpanel.setMinimumSize(new Dimension(150,150));
row1.setLayout(new BoxLayout(row1,BoxLayout.X_AXIS));
row1.setPreferredSize(new Dimension(150,150));
row2.setLayout(new BoxLayout(row2,BoxLayout.X_AXIS));
row3.setLayout(new BoxLayout(row3,BoxLayout.X_AXIS));
row4.setLayout(new BoxLayout(row4,BoxLayout.X_AXIS));
buttonpanel.setLayout(new BoxLayout(buttonpanel,BoxLayout.Y_AXIS));
elipse.addActionListener(this);
rectangle.addActionListener(this);
line.addActionListener( this);
save.addActionListener( this);
erase.addActionListener( this);
buttonpanel.add(Box.createRigidArea(new Dimension(10,10)));
row1.add(elipse);
row1.add(Box.createRigidArea(new Dimension(5,0)));
row1.add(rectangle);
buttonpanel.add(row1);
buttonpanel.add(Box.createRigidArea(new Dimension(10,10)));
row2.add(line);
row2.add(Box.createRigidArea(new Dimension(5,0)));
row2.add(empty);
buttonpanel.add(row2);
buttonpanel.add(Box.createRigidArea(new Dimension(10,10)));
row3.add(save);
buttonpanel.add(row3);
buttonpanel.add(Box.createRigidArea(new Dimension(10,10)));
row4.add(erase);
buttonpanel.add(row4);
return buttonpanel;
}
//To save the image drawn
public void save()
{
try
{
ByteArrayOutputStream bos = new ByteArrayOutputStream();
JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(bos);
JFileChooser fc = new JFileChooser();
fc.showSaveDialog(this);
encoder.encode(image);
byte[] jpgData = bos.toByteArray();
FileOutputStream fos = new FileOutputStream(fc.getSelectedFile()+".jpeg");
fos.write(jpgData);
fos.close();
//add replce confirmation here
}
catch (IOException e)
{
System.out.println(e);
}
}
public void mouseClicked(MouseEvent arg0) {
// TODO Auto-generated method stub
}
@Override
public void mouseEntered(MouseEvent arg0) {
}
public void mouseExited(MouseEvent arg0) {
// TODO Auto-generated method stub
}
public void mousePressed(MouseEvent e)
{
if(selected=="line"||selected=="erase")
{
start=e.getPoint();
client.broadcast(start,"start", selected,"press");
}
else if(selected=="elipse"||selected=="rect")
{
mp = e.getPoint();
client.broadcast(mp,"mp", selected,"press");
}
}
public void mouseReleased(MouseEvent e)
{
if(start!=null)
{
if(selected=="line")
{
end=e.getPoint();
client.broadcast(end,"end", selected,"release");
}
else if(selected=="elipse"||selected=="rect")
{
end.x = Math.max(mp.x,e.getX());
end.y = Math.max(mp.y,e.getY());
client.broadcast(end,"end", selected,"release");
}
draw();
}
//start=null;
}
public void mouseDragged(MouseEvent e)
{
if(end==null)
end = new Point();
if(start==null)
start = new Point();
if(selected=="line")
{
end=e.getPoint();
client.broadcast(end,"end", selected,"drag");
}
else if(selected=="erase")
{
start=e.getPoint();
erase();
client.broadcast(start,"start", selected,"drag");
}
else if(selected=="elipse"||selected=="rect")
{
start.x = Math.min(mp.x,e.getX());
start.y = Math.min(mp.y,e.getY());
end.x = Math.max(mp.x,e.getX());
end.y = Math.max(mp.y,e.getY());
client.broadcast(start,"start", selected,"drag");
client.broadcast(end,"end", selected,"drag");
}
repaint();
}
@Override
public void mouseMoved(MouseEvent arg0) {
// TODO Auto-generated method stub
}
public void actionPerformed(ActionEvent e)
{
if(e.getSource()==elipse)
selected="elipse";
if(e.getSource()==line)
selected="line";
if(e.getSource()==rectangle)
selected="rect";
if(e.getSource()==save)
save();
if(e.getSource()==erase)
{
selected="erase";
erase();
}
}
}
class Button extends JButton
{
String name;
public Button(String name)
{
this.name=name;
Dimension buttonSize = new Dimension(35,35);
setMaximumSize(buttonSize);
}
public void paintComponent(Graphics g)
{
super.paintComponent(g);
Graphics2D g2 = (Graphics2D)g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
//g2.setStroke(new BasicStroke(1.2f));
if (name == "line") g.drawLine(5,5,30,30);
if (name == "elipse") g.drawOval(5,7,25,20);
if (name== "rect") g.drawRect(5,5,25,23);
}
}