验证码的生成

来源：互联网发布：中国民营企业调查数据编辑：程序博客网时间：2024/05/16 02:43

　　现在的项目中，验证码已经成为登录界面必不可少的一项，那么验证码是如何生成的？

package com.bjpowernode.drp.util.Servlet;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;import javax.servlet.http.HttpSession;public class AuthImageServlet extends HttpServlet   {         private static final String CONTENT_TYPE = "text/html; charset=gb2312";       //设置字母的大小,大小       private Font mFont = new Font("Times New Roman", Font.PLAIN, 17);       public void init() throws ServletException       {           super.init();       }       Color getRandColor(int fc,int bc)       {           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);       }         public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException       {           response.setHeader("Pragma","No-cache");           response.setHeader("Cache-Control","no-cache");           response.setDateHeader("Expires", 0);           //表明生成的响应是图片           response.setContentType("image/jpeg");                      int width=100, height=18;           BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);                      Graphics g = image.getGraphics();           Random random = new Random();           g.setColor(getRandColor(200,250));           g.fillRect(1, 1, width-1, height-1);           g.setColor(new Color(102,102,102));           g.drawRect(0, 0, width-1, height-1);           g.setFont(mFont);             g.setColor(getRandColor(160,200));             //画随机线           for (int i=0;i<155;i++)           {               int x = random.nextInt(width - 1);               int y = random.nextInt(height - 1);               int xl = random.nextInt(6) + 1;               int yl = random.nextInt(12) + 1;               g.drawLine(x,y,x + xl,y + yl);           }             //从另一方向画随机线           for (int i = 0;i < 70;i++)           {               int x = random.nextInt(width - 1);               int y = random.nextInt(height - 1);               int xl = random.nextInt(12) + 1;               int yl = random.nextInt(6) + 1;               g.drawLine(x,y,x - xl,y - yl);           }             //生成随机数,并将随机数字转换为字母           String sRand="";           for (int i=0;i<6;i++)           {               int itmp = random.nextInt(26) + 65;               char ctmp = (char)itmp;               sRand += String.valueOf(ctmp);               g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));               g.drawString(String.valueOf(ctmp),15*i+10,16);           }             HttpSession session = request.getSession(true);           session.setAttribute("rand",sRand);           g.dispose();           ImageIO.write(image, "JPEG", response.getOutputStream());       }       public void destroy()       {       }   }

　　建立Servlet，写入上面相应的代码，并在配置文件中对Servlet进行配置。那么访问这个Servlet的时候就能产生类似图片的验证码。

　　效果图：

　　图片中的值已经存在放Session中了，在进行验证码验证的时候，只需要将输入的验证码和Session中的值进行比对就可以了。

1 0