程序功能在Applet上使用鼠標(biāo)在屏幕上隨意畫直線和畫點(diǎn)

1、1 程序功能：在Applet上使用鼠標(biāo)在屏幕上隨意畫直線和畫點(diǎn)。用戶點(diǎn)擊“畫線”按鈕可畫直線，點(diǎn)擊“畫點(diǎn)”按鈕可畫連續(xù)點(diǎn)，點(diǎn)擊“清除”按鈕可清除畫面上的所有內(nèi)容。 2 編寫LX8_9.java程序文件，源代碼如下。Button line, point, clear; MyCanvas2 c; public void init() c=new MyCanvas2(); c.setSize(350,200); c.setBackground(Color.green); line=new Button("畫線"); point=new Button("畫點(diǎn)")

2、; clear=new Button("清除"); add(line); add(point); add(clear); add(c); line.addActionListener(this); point.addActionListener(this); clear.addActionListener(this); public void actionPerformed(ActionEvent e) if (e.getSource()=line) / 設(shè)為畫直線模式 c.mode=0; else if (e.getSource()=point) / 設(shè)為畫連續(xù)點(diǎn)模式 c

3、.mode=1; else if (e.getSource()=clear) / 清除畫面 c.points=new Vector(); c.x1= -1; c.repaint(); class MyCanvas2 extends Canvas implements MouseListener,MouseMotionListener int x1, y1, x2, y2, mode; Vector points=new Vector(); MyCanvas2() addMouseListener(this); addMouseMotionListener(this); public void

4、paint(Graphics g) for (int i=0;i<points.size();i+) / 所有操作結(jié)果被重新畫出 Rectangle r=(Rectangle)points.elementAt(i); g.drawLine(r.x, r.y, r.width, r.height); if (x1!= -1 && mode =0) /畫當(dāng)前直線 g.drawLine(x1, y1, x2, y2); public void mousePressed(MouseEvent e) / 記錄起點(diǎn)坐標(biāo) x1=e.getX(); y1=e.getY(); public

5、 void mouseDragged(MouseEvent e) if (mode=0) / 記錄當(dāng)前坐標(biāo) x2=e.getX(); y2=e.getY(); else / 畫連續(xù)點(diǎn)時(shí)保存每一個(gè)筆畫的起點(diǎn)和當(dāng)前坐標(biāo) points.addElement(new Rectangle(x1, y1, e.getX(), e.getY(); x1=e.getX(); y1=e.getY(); repaint(); public void mouseReleased(MouseEvent e) if (mode=0) / 保存當(dāng)前直線的起點(diǎn)和終點(diǎn)坐標(biāo) points.addElement(new Rectangle(x1, y1, e.getX(), e.getY(); public void mouseClicked(MouseEvent e) public void mouseEntered(MouseEvent e) public void mouseExited(MouseEvent e) public void mouseMoved(MouseEvent e) 3 編譯源程