JFrame画图基础和事件监听

消息框

JOptionPane.showMessageDialog(mine.this, "删除不成功!");

画图

class MyJPanel extends JPanel //继承面板类
{
    public void paint(Graphics g) //覆盖父类的方法,paint相当于画图
    {
        g.drawOval(30, 30, 80, 80);  //画圆
        g.drawLine(100, 100, 200, 200); //画直线 ,两点坐标
        g.setColor(Color.RED);
        g.drawRect(50,50,50,50);
        g.draw3DRect(100, 100, 100, 100,true); //画矩形 ,参数是做上角坐标和长宽
        g.setColor(Color.BLUE);
        g.fillRect(100, 100, 100, 100); //填充矩形
        g.fill3DRect(50, 50, 50, 50, false); //填充3d效果的矩形
        
    }
}

导入图片

Image tp=Toolkit.getDefaultToolkit().getImage(Panel.class.getResource("/龙猫2.jpg")); //固定格式,得到图片
        g.drawImage(tp, 30, 30, 100, 100, this); //画图

绘文字

g.setColor(Color.BLUE);
        g.setFont(new Font("华文彩云",Font.BOLD,50));
        g.drawString("很强", 100, 100);

监听事件

JButton bt=new JButton("运行");
        bt.addActionListener(this);  //自己的
        MyListener jt=new MyListener();
        bt.addActionListener(jt);  //另一个
        bt.setActionCommand("yunxing");

    public void actionPerformed(ActionEvent e) //必须实现监听器的抽象方法
    {
        if(e.getActionCommand()=="yunxing")
        {
            System.out.println("运行成功");
        }
    }

}

class MyListener implements ActionListener  //继承父类
{
    public void actionPerformed(ActionEvent e) //实现这个抽象函数
    {
        if(e.getActionCommand()=="yunxing") System.out.println("很强");
    }
}

键盘事件

this.add(mjp);
this.addKeyListener(mjp); //要添加监听器

class MyJPanel extends JPanel implements KeyListener //给面板实现键盘监听接口,以下3个函数必须实现
{
    int x=50,y=50;
    public void paint(Graphics g)
    {
        super.paint(g); //调用父类
        g.fillRect(x, y, 50, 50); //画矩形
    }
    public void keyPressed(KeyEvent e) { //按键事件
        // TODO Auto-generated method stub
        //System.out.println("键盘被按下");
        //System.out.println((char)e.getKeyCode());
        if(e.getKeyCode()==KeyEvent.VK_UP){    y-=5; }
        else if(e.getKeyCode()==KeyEvent.VK_DOWN){ y+=5; }
        else if(e.getKeyCode()==KeyEvent.VK_LEFT){ x-=5; }
        else if(e.getKeyCode()==KeyEvent.VK_RIGHT){ x+=5; }
        this.repaint();
        
    }
    public void keyReleased(KeyEvent e) { //松开事件
        // TODO Auto-generated method stub
        
    }
    public void keyTyped(KeyEvent e) { //打字事件
        // TODO Auto-generated method stub
        
    }
}

鼠标事件

this.add(mjp);
this.addMouseListener(mjp);

class MyJPanel extends JPanel implements MouseListener //以下5个函数要写
{
    int x=50,y=50;
    public void paint(Graphics g)
    {
        super.paint(g);
        g.drawOval(x, y, 50, 50);
    }
    public void mouseClicked(MouseEvent e) //鼠标点击事件
    {
        System.out.println(e.getX()+","+e.getY());
        x=e.getX();
        y=e.getY();
        this.repaint();
    }
    public void mouseReleased(MouseEvent e) //松开
    {
        
    }
    public void mouseExited(MouseEvent e)  //出界面
    {
        
    }
    public void mousePressed(MouseEvent e) //按下
    {
        
    }
    public void mouseEntered(MouseEvent e) //进入界面
    {
        
    }
}

增加新的对话窗口

public void actionPerformed(ActionEvent e) //原来窗口的监听
    {
        if(e.getActionCommand()=="tianjia")
        {
            Add add=new Add(this,"ok",true); //新的对话界面
          
        }
    }
class Add extends JDialog implements ActionListener
{
    public Add(Frame fck,String ckm,boolean msck)
    {
        super(fck,ckm,msck);  //父类
        //this.setTitle("学生信息");
        this.setSize(500, 500);
        this.setLocation(100, 100);
        JButton jb=new JButton("取消");
        jb.addActionListener(this);
        jb.setActionCommand("quxiao");
        this.add(jb);
        this.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
        this.setVisible(true);
    }
    public void actionPerformed(ActionEvent e)
    {
        if(e.getActionCommand()=="quxiao")
        {
            this.dispose(); //关闭窗口
        }
    }
}