java第一次上机实验验证码

package javashiyan;

import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.*;

public  class Yanzhen extends JFrame
{
    //定义成员变量
    private Mypanel mp;
    private JButton b;
    private JTextField txt;
    private ActionListener listener;
    
    public Yanzhen()
    {
        Realize();
    }
    public void Realize()
    {
        JFrame f=new JFrame("验证码");
        //实例化
        b=new JButton();
        b.addActionListener(listener);
        ActionEvent e;
        b.setIcon(new ImageIcon("D://button//刷新.jpg"));//载入图片
        b.setLocation(200,100);//设置位置
        b.setSize(32,32);//设置大小
        b.setVisible(true);//设置显示
        
        txt=new JTextField();
        txt.setSize(90,30);
        txt.setLocation(10,100);
        txt.setVisible(true);
        
        mp=new Mypanel();
        mp.setSize(100,30);
        mp.setLocation(100,100);
        
        JButton jb=new JButton();
        
        
        f.add(mp);
        f.add(b);
        f.add(txt);
        
        f.setLayout(null);
        f.setSize(400, 400);//设置界面大小
        f.getContentPane().setBackground(Color.white);//设置界面的背景颜色
        f.getContentPane().setVisible(true);
        f.setVisible(true);
    }



    public void actionPerformed(ActionEvent e) {
        // TODO Auto-generated method stub
        
        
    }
}

package javashiyan;

import java.awt.*;
import java.util.*;

public class Mypanel extends Panel {
    public void paint(Graphics g)
    {
        int height = 50;
        int width = 90;
        //验证码框背景颜色
        g.setColor(Color.white);
        //填充验证码背景
        g.fillRect(0, 0, width, height);
        g.setColor(Color.BLACK);
        g.drawRect(0, 0, width-1, height-1);
        Random r = new Random();
        for(int i = 0;i<100;i++)
        {
            int x = r.nextInt(width)-1;
            int y = r.nextInt(height)-1;
            g.drawOval(x, y, 2, 2);//画干扰的圆点
        }
        for(int i=0;i<3;i++)
        {
            int x1=r.nextInt(width)-1;
            int y1=r.nextInt(height)-1;
            int x2=r.nextInt(width)-1;
            int y2=r.nextInt(height)-1;
            g.drawLine(x1, y1, x2, y2);//画干扰的线段
        }
        
        g.setFont(new Font("黑体",Font.BOLD,20));//设置验证码字体以及大小
        g.setColor(Color.BLUE);//设置验证码字体颜色
        //生成随机验证码
        char[] tmp = ("0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ").toCharArray();
        StringBuilder sb = new StringBuilder();
        for(int i = 0;i<4;i++)
        {
            int pos = r.nextInt(tmp.length);
            char c = tmp[pos];
            sb.append(c + " ");
        }
        g.drawString(sb.toString(), 10, 15);//写入验证码
    }
}

package javashiyan;



import java.util.Random;

public class main {

    public static void main(String[] args) 
    {    
            Yanzhen dang=new Yanzhen();
    }

}