验证码的代码

package cn.itcast.servlet.web;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class CheckCodeServlet
 */
@WebServlet("/CheckCodeServlet")
public class CheckCodeServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public CheckCodeServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //1.创建一个对象，这个对象在内存中就代表图片(验证码图片对象)
        int width=100;
        int height=50;
        BufferedImage image=new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        //2.美化图片
        //2.1填充图片颜色
        Graphics g = image.getGraphics();//获取画笔的对象
        g.setColor(Color.pink);//设置画笔的颜色
        g.fillRect(0, 0, width, height);//填充图片
        //2.2画边框
        g.setColor(Color.blue);
        g.drawRect(0, 0, width-1, height-1);
        
        String str="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
        //生成随机角标
        Random ran=new Random();
        for (int i = 1; i <=4; i++) {
            int index = ran.nextInt(str.length());
            //获取字符
            char ch = str.charAt(index);
            //2.3写验证码
            g.drawString(ch+"",width/5*i,height/2);
        }
        //2.4画干扰线
        g.setColor(Color.green);
        //随机生成坐标点
        for (int i = 0; i < 10; i++) {
            int x1=ran.nextInt(width);//生成一个0-width的随机值，不包括width
            int x2=ran.nextInt(width);
            int y1=ran.nextInt(height);
            int y2=ran.nextInt(height);
            g.drawLine(x1, x2, y1, y2);
        }
        
        
        
        //3.将图片输出到页面展示
        //将内存中的图片输出到页面
        ImageIO.write(image, "jpg", response.getOutputStream());
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}