javaWeb中的验证码

　　在做网站中，经常用到验证码验证什么的。如登陆验证...随着技术的升级，验证码技术也升级了。验证码的出现时为了防止‘暴力破解’账号。下面我就讲我最近所学的一个普通写验证码的代码整理如下:

　　第一步:servlet中的代码

  1 package com.zuxia.servlet;
  2 
  3 import java.awt.BasicStroke;  
  4 import java.awt.Color;  
  5 import java.awt.Font;  
  6 import java.awt.Graphics;  
  7 import java.awt.Graphics2D;  
  8 import java.awt.GraphicsEnvironment;  
  9 import java.awt.geom.AffineTransform;  
 10 import java.awt.image.BufferedImage;  
 11 import java.io.IOException;  
 12 import java.util.Random;  
 13   
 14 import javax.imageio.ImageIO;  
 15 import javax.servlet.ServletException;  
 16 import javax.servlet.http.HttpServlet;  
 17 import javax.servlet.http.HttpServletRequest;  
 18 import javax.servlet.http.HttpServletResponse;  
 19 import javax.servlet.http.HttpSession;  
 20   
 21 public class DrawImageCode extends HttpServlet {  
 22   
 23     private Color getRandColor(int s, int e) {  
 24         Random random = new Random();  
 25         if (s > 255)  
 26             s = 255;  
 27         if (e > 255)  
 28             e = 255;  
 29         int r = random.nextInt(e - s) + s; // 随机生成RGB中的R值  
 30         int g = random.nextInt(e - s) + s; // 随机生成RGB中的G值  
 31         int b = random.nextInt(e - s) + s; // 随机生成RGB中的B值  
 32         return new Color(r, g, b);  
 33     }  
 34   
 35   
 36     public void doGet(HttpServletRequest request, HttpServletResponse response)  
 37             throws ServletException, IOException {  
 38   
 39         this.doPost(request, response);  
 40     }  
 41   
 42     public void doPost(HttpServletRequest request, HttpServletResponse response)  
 43             throws ServletException, IOException {  
 44   
 45         response.setHeader("Pragma", "No-cache");  
 46         response.setHeader("Cache-Control", "No-cache");  
 47         response.setDateHeader("Expires", 0);  
 48         //指定生成的响应图片  
 49         response.setContentType("image/jpeg");  
 50         int width = 150;                            //指定生成验证码图片的宽度  
 51         int heigh = 60;                         //指定生成验证码图片的高度  
 52             //获得图像数据缓冲对象  
 53         BufferedImage bi = new BufferedImage(width,heigh,BufferedImage.TYPE_INT_RGB);  
 54             //获得图形上下文的抽象基类  
 55         Graphics g = bi.getGraphics();  
 56         Random r = new Random();  
 57         Font f = new Font("黑体",Font.PLAIN,60);  //定义字体样式  
 58         g.setColor(getRandColor(200, 250));     //设置背景颜色  
 59         g.fillRect(0, 0, width, heigh);         //绘制背景  
 60         g.setFont(f);                           //设置字体  
 61         g.setColor(getRandColor(180, 200));     //设置前景颜色  
 62           
 63           
 64         Graphics2D g2d = (Graphics2D) g;  
 65         //画一条折线       
 66         //BasicStroke bs=new BasicStroke(5f,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL); //创建一个供画笔选择线条粗细的对象  
 67         //g2d.setStroke(bs);              //改变线条的粗细  
 68         g2d.setColor(Color.DARK_GRAY);      //设置当前颜色为预定义颜色中的深灰色  
 69         int[] xPoints=new int[8];  
 70         int[] yPoints=new int[8];  
 71         for(int j=0;j<8;j++){  
 72             xPoints[j]=r.nextInt(width - 1);  
 73             yPoints[j]=r.nextInt(heigh - 1);  
 74         }  
 75         g2d.drawPolyline(xPoints, yPoints,8);  
 76           
 77         String sRand = "";  
 78         String ctmp = "";  
 79         int itmp = 0;  
 80         for (int i = 0; i < 6; i++) {  
 81             switch (r.nextInt(2)) {  
 82             case 1:  
 83                 itmp = r.nextInt(26) + 65; // 生成A~Z的字母  
 84                 ctmp = String.valueOf((char) itmp);  
 85                 break;  
 86             default:  
 87                 itmp = r.nextInt(10) + 48; // 生成0~9的数字  
 88                 ctmp = String.valueOf((char) itmp);  
 89                 break;  
 90             }  
 91             sRand += ctmp;  
 92             //设置每个字符的随机颜色  
 93             Color color = new Color(20 + r.nextInt(210), 20 + r.nextInt(210), 20 + r.nextInt(210));  
 94             g2d.setColor(color);  
 95             //设置每个字符的随机字体  
 96             g2d.setFont(this.getRandomFont());  
 97             //设置每个字符的随机旋转  
 98             AffineTransform at = new AffineTransform();  
 99             int number = r.nextInt(3)-1;  
100             double role = number*r.nextDouble()*(Math.PI/4);  
101             at.setToRotation(role,25*i+5,55-r.nextInt(20)); //role:旋转角度,后面两个参数是设置围绕坐标点旋转  
102             g2d.setTransform(at);  
103               
104             g2d.drawString(ctmp, 25*i+5,55-r.nextInt(20));  
105         }  
106            HttpSession session = request.getSession(true);  
107            session.setMaxInactiveInterval(5*60);//设置session对象5分钟失效  
108            session.setAttribute("code", sRand.toString());  
109   
110            g2d.dispose();  
111   
112             System.out.println(sRand);  
113             ImageIO.write(bi, "JPEG", response.getOutputStream());  
114               
115               
116     }  
117       
118      
119      public static Font getRandomFont() {    
120             //String[] fonts = {"Georgia", "Verdana", "Arial", "Tahoma", "Time News Roman", "Courier New", "Arial Black", "Quantzite"};    
121             String[] fonts = {"a_TrianglerCmUp","Astarisborn","WishfulWaves"};  
122             Random r = new  Random();  
123            int fontIndex = r.nextInt(fonts.length);  
124             return new Font(fonts[fontIndex],  r.nextInt(3),50-r.nextInt(20));    
125         }  
126 }

　　　　第二步：jsp页面引用这servlet，用以显示效果

 1 <html>
 2 <head>
 3 <tiltle>我是验证码页面哦</title>
 4 
 5 </head>
 6 
 7 <body>
 8      <div><img src="DrawImageCode " alt="验证码"/></div>
 9 </body>
10 </html>

　　提示：DrawImageCode是已建好的servlet的路径名哦......