彩色验证码的实现

来源：互联网发布：登陆淘宝编辑：程序博客网时间：2024/05/10 19:56

<%@ page contentType="image/jpeg" pageEncoding="UTF-8" import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*" %>
    <%!
    Color getRandColor(int fc,int bc){//给定范围获得随机颜色
            Random random = new Random();
            if(fc>255) fc=255;
            if(bc>255) bc=255;
            int r=fc+random.nextInt(bc-fc);
            int g=fc+random.nextInt(bc-fc);
            int b=fc+random.nextInt(bc-fc);
            return new Color(r,g,b);
            }
    %>
    <%
    //设置页面不缓存
    response.setHeader("Pragma","No-cache");
    response.setHeader("Cache-Control","no-cache");
    response.setDateHeader("Expires", 0);

    // 在内存中创建图象
    int width=60, height=20;
    BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

// 获取图形上下文
Graphics g = image.getGraphics();

//生成随机类
Random random = new Random();

    // 设定背景色
    g.setColor(getRand(200,250));
    g.fillRect(0, 0, width, height);

    //设定字体
    g.setFont(new Font("Times New Roman",Font.BOLD,18));
    g.setColor(getRandColor(160,200));
     for (int i=0;i<155;i++)
    {
     int x = random.nextInt(width);
        int y = random.nextInt(height);
     int x1 = random.nextInt(12);
     int y1 = random.nextInt(12);
     g.drawLine(x, y, x+x1, y+y1);
    }
    // 取随机产生的认证码(4位数字)
     String sRand = "";

     for(int i=0; i<4; i++) {
    String rand=String.valueOf(random.nextInt(10));
sRand+=rand;
     g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));

     g.drawString(rand,13*i+6,16);
}
     // 将认证码存入SESSION
    session.setAttribute("rand",sRand);

// 随机产生20条干扰线，使图象中的认证码不易被其它程序探测到

// 释放所用到的图形上下文的资源
g.dispose();

// 输出图象到页面
ImageIO.write(image, "JPEG", response.getOutputStream());