jsp的验证码实现

package com.xunfang.demo;

import java.awt.Color;
import java.awt.Font;
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.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * @title://演示输出验证码
 * @author:阳阳
 * @date: 2015-5-13
 */
public class ServletResponsw1 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        //创建图片
        int width =120;
        int height = 30;
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        //拿到此图片的画笔
        Graphics g = image.getGraphics();
        
        //设定边框
        g.setColor(Color.blue);
        g.drawRect(0, 0, width, height);
        g.setColor(Color.gray);
        g.fillRect(1, 1, width-2, height-2);
        
        //增加干扰圆点
        Random r = new Random();
        g.setColor(Color.green);
        for (int i = 0; i < 100; i++) {
            g.drawOval(1, 1, r.nextInt(width),r.nextInt(height));
        }
        
        //设定中文
        g.setColor(Color.yellow);
        g.setFont(new Font("楷体", Font.BOLD, 1));
        String s = "增加分析验证码的难IHAVEmoney度可以加30条干扰线中国好声音深圳讯方通信技术有限公司刘德华成龙";
//输出4个字符 StringBuffer sb
= new StringBuffer(); for (int i = 0; i <4; i++) { char c = s.charAt(r.nextInt(s.length())); sb.append(c); g.drawString(c+"", 20+20*i+r.nextInt(5)*((i%2)==0?1:-1),20+r.nextInt(5)*((i%2)==0?1:-1)); } request.getSession().setAttribute("code", sb.toString()); ImageIO.write(image, "img", response.getOutputStream()); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }

 

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