1 package com.logcd.servlet;
  2 
  3 import java.awt.Color;
  4 import java.awt.Font;
  5 import java.awt.Graphics2D;
  6 import java.awt.image.BufferedImage;
  7 import java.util.Random;
  8 import javax.imageio.ImageIO;
  9 import javax.servlet.*;
 10 import java.io.*;
 11 import javax.servlet.http.*;
 12 import javax.servlet.ServletException;
 13 import javax.servlet.http.HttpServlet;
 14 import javax.servlet.http.HttpServletRequest;
 15 import javax.servlet.http.HttpServletResponse;
 16 
 17 @SuppressWarnings("serial")
 18 public class RandomCode extends HttpServlet {
 19 
 20     public void doGet(HttpServletRequest request, HttpServletResponse response)
 21             throws ServletException, IOException {
 22 
 23         this.doPost(request, response);
 24     }
 25 
 26     public void doPost(HttpServletRequest request, HttpServletResponse response)
 27             throws ServletException, IOException {
 28 
 29         // 驗(yàn)證碼圖片的寬度。
 30         int width = 70;
 31         // 驗(yàn)證碼圖片的高度,。
 32         int height = 30;
 33         BufferedImage buffImg = new BufferedImage(width, height,
 34                 BufferedImage.TYPE_INT_RGB);
 35         Graphics2D g = buffImg.createGraphics();
 36 
 37         // 創(chuàng)建一個(gè)隨機(jī)數(shù)生成器類(lèi),。
 38         Random random = new Random();
 39 
 40         // 設(shè)定圖像背景色(因?yàn)槭亲霰尘埃云?
 41         g.setColor(getRandColor(200, 250));
 42         g.fillRect(0, 0, width, height);
 43         // 創(chuàng)建字體,，字體的大小應(yīng)該根據(jù)圖片的高度來(lái)定,。
 44         Font font = new Font("Times New Roman", Font.HANGING_BASELINE, 28);
 45         // 設(shè)置字體。
 46         g.setFont(font);
 47 
 48         // 畫(huà)邊框,。
 49         g.setColor(Color.BLACK);
 50         g.drawRect(0, 0, width - 1, height - 1);
 51         // 隨機(jī)產(chǎn)生155條干擾線(xiàn),，使圖象中的認(rèn)證碼不易被其它程序探測(cè)到。
 52 //g.setColor(Color.GRAY);
 53         g.setColor(getRandColor(160,200));
 54         for (int i = 0; i < 155; i++) {
 55             int x = random.nextInt(width);
 56             int y = random.nextInt(height);
 57             int xl = random.nextInt(12);
 58             int yl = random.nextInt(12);
 59             g.drawLine(x, y, x + xl, y + yl);
 60         }
 61 
 62         // randomCode用于保存隨機(jī)產(chǎn)生的驗(yàn)證碼,，以便用戶(hù)登錄后進(jìn)行驗(yàn)證,。
 63         StringBuffer randomCode = new StringBuffer();
 64 
 65         // 設(shè)置默認(rèn)生成4個(gè)驗(yàn)證碼
 66         int length = 4;
 67         // 設(shè)置備選驗(yàn)證碼:包括"a-z"和數(shù)字"0-9"
 68         String base = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
 69 
 70         int size = base.length();
 71 
 72         // 隨機(jī)產(chǎn)生4位數(shù)字的驗(yàn)證碼。
 73         for (int i = 0; i < length; i++) {
 74             // 得到隨機(jī)產(chǎn)生的驗(yàn)證碼數(shù)字,。
 75             int start = random.nextInt(size);
 76             String strRand = base.substring(start, start + 1);
 77 
 78             // 用隨機(jī)產(chǎn)生的顏色將驗(yàn)證碼繪制到圖像中,。
 79 // 生成隨機(jī)顏色(因?yàn)槭亲銮熬埃云?
 80 //g.setColor(getRandColor(1, 100));
 81             
 82 //調(diào)用函數(shù)出來(lái)的顏色相同,，可能是因?yàn)榉N子太接近,，所以只能直接生成
 83             g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));
 84 
 85             g.drawString(strRand, 15 * i + 6, 24);
 86 
 87             // 將產(chǎn)生的四個(gè)隨機(jī)數(shù)組合在一起。
 88             randomCode.append(strRand);
 89         }
 90         // 將四位數(shù)字的驗(yàn)證碼保存到Session中,。
 91         HttpSession session = request.getSession();
 92         session.setAttribute("rand", randomCode.toString());
 93 
 94         //圖象生效
 95         g.dispose();
 96 
 97         // 禁止圖像緩存,。
 98         response.setHeader("Pragma", "no-cache");
 99         response.setHeader("Cache-Control", "no-cache");
100         response.setDateHeader("Expires", 0);
101 
102         response.setContentType("image/jpeg");
103 
104         // 將圖像輸出到Servlet輸出流中。
105         ServletOutputStream sos = response.getOutputStream();
106         ImageIO.write(buffImg, "jpeg", sos);
107         sos.flush();
108         sos.close();
109 
110     }
111 
112     Color getRandColor(int fc, int bc) {// 給定范圍獲得隨機(jī)顏色
113         Random random = new Random();
114         if (fc > 255)
115             fc = 255;
116         if (bc > 255)
117             bc = 255;
118         int r = fc + random.nextInt(bc - fc);
119         int g = fc + random.nextInt(bc - fc);
120         int b = fc + random.nextInt(bc - fc);
121         return new Color(r, g, b);
122     }
123 
124 }

1     <servlet>
2         <servlet-name>RandomCode</servlet-name>
3         <servlet-class>com.logcd.servlet.RandomCode</servlet-class>
4     </servlet>
5     <servlet-mapping>
6         <servlet-name>RandomCode</servlet-name>
7         <url-pattern>/randomCode</url-pattern>
8     </servlet-mapping>

 1 <meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
 2 <meta http-equiv="pragma" content="no-cache"/>
 3 <meta http-equiv="cache-control" content="no-cache"/>
 4 <meta http-equiv="expires" content="0"/>
 5 
 6 <iframe src="http://127.0.0.1/js_test/randomCode" id="codeFrame" name="codeFrame" frameborder="no" border="0" marginwidth="0"
 7      marginheight="0" scrolling="no" allowtransparency="yes" height="35" width="102"></iframe>
 8      <a href="javascript:void(0);" onclick="refreshCode();">看不清,，換一張</a>
 9     <br> 
10     <span id="codeImg"><img border=0 src="randomCode"></span>
11     <a href="javascript:void(0);" onclick="reloadCode()">看不清,，再換一張</a>

 1 function $(id){
 2     return document.getElementById(id);
 3 }
 4 
 5 /**刷新iframe**/
 6 function refreshCode(){
 7     window.frames["codeFrame"].location.reload();
 8 }
 9 
10 /**替換圖片**/
11 function reloadCode(){
12     $("codeImg").innerHTML = "<img border=0 src='randomCode'>";
13 }