JAVA的继承，构造函数，窗体

  1 import java.awt.*;
  2 import javax.swing.*;
  3 import javax.swing.JFrame;
  4 import java.awt.event.WindowListener;
  5 import java.awt.event.WindowEvent;
  6 import java.awt.event.WindowAdapter;
  7 import java.awt.event.ActionListener;
  8 import java.awt.event.ActionEvent;
  9 class QQ extends JFrame   //继承JFrame
 10 {
 11     QQ()  //构造函数
 12     {
 13         display();//调用display()函数
 14     }
 15     JButton btn1;
 16     JButton btn2;
 17     JTextField jtf1;
 18     JPasswordField jpf1; //密码文本
 19     class MyListener extends WindowAdapter //适配器   是扩展  不需要覆盖WindowAdapter中的所有方法 功能代码较多
 20     {
 21         public void windowClosing(WindowEvent e)
 22         {
 23             System.out.println("windowClosing");
 24             int res = JOptionPane.showConfirmDialog(null,"是否退出程序应用","提示", JOptionPane.YES_NO_OPTION); //弹出消息框
 25             System.out.println("res =" + res);
 26             if(res == 0)
 27             {
 28                 System.out.println("退出");
 29                 System.exit(1);// 退出
 30                 System.out.println("退出1"); //不输出  因为exit先执行
 31             }
 32             else if(res == 1)
 33             {
 34                 System.out.println("不退出");
 35                 setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
 36                 //System.exit(1);// 退出
 37                 // 不退出
 38             }
 39         }
 40     }
 41     class BtnAction implements ActionListener  //btn事件
 42     {
 43         public void actionPerformed(ActionEvent e)
 44         {
 45             System.out.println("actionPerformed");
 46             if(jtf1.getText().equals("jk") && jpf1.getText().equals("jk"))
 47             {
 48                 System.out.println("OK");
 49                 dispose();
 50                 (new JFrame("主窗口")).setVisible(true);
 51             }
 52             else
 53             {
 54                 System.out.println("Error");
 55                 JOptionPane.showConfirmDialog(null,"密码错误","提示", JOptionPane.DEFAULT_OPTION);
 56             }
 57         }
 58     }
 59     class BtnAction2 implements ActionListener   //内部类
 60     {
 61         public void actionPerformed(ActionEvent e)
 62         {
 63             Object o = e.getSource();
 64             JButton b = (JButton)o;  //强制类型转换
 65             System.out.println("芝麻开门" + btn2.getText());  //类的成员/函数，可以在内部类中使用
 66             
 67             if(b == btn2) //b.getSource == "注册"
 68             {
 69                 jtf1.setText("");
 70                 jpf1.setText("");
 71             }
 72         }
 73     }
 74     public void display()
 75     {
 76         //JFrame frm = new JFrame(); //窗体
 77         ImageIcon img1 = new ImageIcon("timg.gif"); //背景
 78         JLabel background1 = new JLabel(img1);
 79         this.getLayeredPane().add(background1, new Integer(Integer.MIN_VALUE)); 
 80         //background.setBounds(0, 0, img.getIconWidth(), img.getIconHeight());
 81         background1.setBounds(0, 0, 425, 450);
 82         ImageIcon img2 = new ImageIcon("33.gif"); 
 83         JLabel background2 = new JLabel(img2);
 84         this.getLayeredPane().add(background2, new Integer(Integer.MIN_VALUE)); 
 85         background2.setBounds(0, 0, img2.getIconWidth(), img2.getIconHeight());
 86         
 87         jtf1 = new JTextField(30); //文本
 88         //jtf1.setColumns(10);
 89         jtf1.setSize(200,35);
 90         jtf1.setLocation(130,130);
 91         jpf1 = new JPasswordField(30); //密码文本
 92         //jpf1.setEchoChar('#');     设置密码文本内容
 93         jpf1.setSize(200,35);
 94         jpf1.setLocation(130,180);
 95         
 96         JLabel lab1 = new JLabel("账号："); //标题
 97         Font fnt = new Font("Serief",Font.ITALIC+Font.BOLD,15);
 98         lab1.setFont(fnt);
 99         lab1.setBackground(Color.BLUE); //label的背景颜色
100         lab1.setOpaque(true); //label是否透明
101         lab1.setForeground(Color.YELLOW); //label前景色
102         JLabel lab2 = new JLabel("密码：");
103         lab1.setSize(50,30);
104         lab2.setSize(50,30);
105         lab1.setLocation(70,130);
106         lab2.setLocation(70,180);
107         btn1 = new JButton("登录");
108         btn1.setBounds(100,230,180,50);
109         Image im1 = (new ImageIcon("QQ.png")).getImage(); //图标
110         this.setIconImage(im1);
111         //ImageIcon im2 = new ImageIcon("77.png"); //图标
112         ImageIcon im2 = new ImageIcon("./77.png");
113         btn1.setIcon(im2);
114         this.setLayout(null);  //布局--绝对布局
115         MyListener ltn = new MyListener();  //监听
116         this.addWindowListener(ltn);
117         BtnAction act = new BtnAction();    //btn事件
118         btn1.addActionListener(act);
119         btn2 = new JButton("重置");
120         btn2.setBounds(300,230,100,50);
121         BtnAction2 act2 = new BtnAction2();
122         btn2.addActionListener(act2);
123         //frm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
124         this.setSize(425,325);
125         this.setLocation(700,500);
126         this.setTitle("QQ登录");
127         this.setResizable(false);        
128         this.add(btn1);
129         this.add(btn2);
130         this.add(lab1);
131         this.add(lab2);
132         this.add(jpf1);
133         this.add(jtf1);
134         this.add(background1);
135         this.add(background2);
136         this.setVisible(true);
137         System.out.println("OK");
138     }
139     public static void main(String[] args)
140     {
141         QQ Event1 = new QQ();
142         System.out.println("OK");
143     }
144 }