ImageServlet.java
1 package com.yu;
2
3 import javax.servlet.http.HttpServlet;
4 import javax.servlet.http.HttpServletRequest;
5 import javax.servlet.http.HttpServletResponse;
6 import javax.servlet.http.HttpSession;
7 import javax.servlet.ServletException;
8 import javax.servlet.ServletOutputStream;
9 import javax.imageio.ImageIO;
10 import java.io.IOException;
11 import java.awt.image.BufferedImage;
12 import java.awt.*;
13 import java.util.Random;
14
15
16 public class ImageServlet extends HttpServlet {
17 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
18 doGet(request, response);
19 }
20
21 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
22 }
23
24 // 验证码图片的宽度。
25 private int width = 60;
26
27 // 验证码图片的高度。
28 private int height = 20;
29
30 // 验证码字符个数
31 private int codeCount = 4;
32
33 private int x = 0;
34
35 // 字体高度
36 private int fontHeight;
37
38 private int codeY;
39
40 char[] codeSequence = {'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',
41 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W',
42 'X', 'Y', 'Z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9'};
43
44 /**
45 * 初始化验证图片属性
46 */
47 public void init() throws ServletException {
48 // 从web.xml中获取初始信息
49 // 宽度
50 String strWidth = this.getInitParameter("width");
51 // 高度
52 String strHeight = this.getInitParameter("height");
53 // 字符个数
54 String strCodeCount = this.getInitParameter("codeCount");
55
56 System.out.println("strWidth=="+strWidth+"strHeight=="+strHeight+"strCodeCount=="+strCodeCount);
57
58 // 将配置的信息转换成数值
59 try {
60 if (strWidth != null && strWidth.length() != 0) {
61 width = Integer.parseInt(strWidth);
62 if (strHeight != null && strHeight.length() != 0) {
63 height = Integer.parseInt(strHeight);
64 }
65 if (strCodeCount != null && strCodeCount.length() != 0) {
66 codeCount = Integer.parseInt(strCodeCount);
67 }
68 }
69 }catch(NumberFormatException e){
70
71 }
72
73 x = width / (codeCount + 1);
74 fontHeight = height - 2;
75 codeY = height - 4;
76
77 }
78
79 protected void service(HttpServletRequest req, HttpServletResponse resp)
80 throws ServletException, java.io.IOException {
81
82 // 定义图像buffer
83 BufferedImage buffImg = new BufferedImage(width, height,
84 BufferedImage.TYPE_INT_RGB);
85 Graphics2D g = buffImg.createGraphics();
86
87 // 创建一个随机数生成器类
88 Random random = new Random();
89
90 // 将图像填充为白色
91 g.setColor(Color.WHITE);
92 g.fillRect(0, 0, width, height);
93
94 // 创建字体，字体的大小应该根据图片的高度来定。
95 Font font = new Font("Fixedsys", Font.PLAIN, fontHeight);
96 // 设置字体。
97 g.setFont(font);
98
99 // 画边框。
100 g.setColor(Color.BLACK);
101 g.drawRect(0, 0, width - 1, height - 1);
102
103 // 随机产生160条干扰线，使图象中的认证码不易被其它程序探测到。
104 g.setColor(Color.cyan);
105 for (int i = 0; i < 160; i++) {
106 int x = random.nextInt(width);
107 int y = random.nextInt(height);
108 int xl = random.nextInt(12);
109 int yl = random.nextInt(12);
110 g.drawLine(x, y, x + xl, y + yl);
111 }
112
113 // randomCode用于保存随机产生的验证码，以便用户登录后进行验证。
114 StringBuffer randomCode = new StringBuffer();
115 int red = 0, green = 0, blue = 0;
116
117 // 随机产生codeCount数字的验证码。
118 for (int i = 0; i < codeCount; i++) {
119 // 得到随机产生的验证码数字。
120 String strRand = String.valueOf(codeSequence[random.nextInt(36)]);
121 // 产生随机的颜色分量来构造颜色值，这样输出的每位数字的颜色值都将不同。
122 red = random.nextInt(255);
123 green = random.nextInt(255);
124 blue = random.nextInt(255);
125 // 用随机产生的颜色将验证码绘制到图像中。
126 g.setColor(new Color(red, green, blue));
127 g.drawString(strRand, (i + 1) * x, codeY);
128
129 // 将产生的四个随机数组合在一起。
130 randomCode.append(strRand);
131 }
132 // 将四位数字的验证码保存到Session中。
133 HttpSession session = req.getSession();
134 session.setAttribute("validateCode", randomCode.toString());
135
136 // 禁止图像缓存。
137 resp.setHeader("Pragma", "no-cache");
138 resp.setHeader("Cache-Control", "no-cache");
139 resp.setDateHeader("Expires", 0);
140
141 resp.setContentType("image/jpeg");
142
143 // 将图像输出到Servlet输出流中。
144 ServletOutputStream sos = resp.getOutputStream();
145 ImageIO.write(buffImg, "jpeg", sos);
146 sos.close();
147 }
148 }
ResultServlet.java
1 package com.yu;
2
3 import javax.servlet.http.HttpServlet;
4 import javax.servlet.http.HttpServletRequest;
5 import javax.servlet.http.HttpServletResponse;
6 import javax.servlet.ServletException;
7 import java.io.IOException;
8 import java.io.PrintWriter;
9
10 /**
11 * Created by IntelliJ IDEA.
12 * User: Administrator
13 * Date: 2009-11-18
14 * Time: 21:25:44
15 * To change this template use File | Settings | File Templates.
16 */
17 public class ResultServlet extends HttpServlet {
18
19
20 public void doGet(HttpServletRequest request, HttpServletResponse response)
21 throws ServletException, IOException {
22
23 doPost(request, response);
24 }
25 public void doPost(HttpServletRequest request, HttpServletResponse response)
26 throws ServletException, IOException {
27
28 response.setContentType("text/html;charset=utf-8");
29 String validateC = (String) request.getSession().getAttribute("validateCode");
30 String veryCode = request.getParameter("c");
31 System.out.println(veryCode);
32 System.out.println(validateC);
33 PrintWriter out = response.getWriter();
34 veryCode=veryCode.toUpperCase();
35 if (veryCode == null || "".equals(veryCode)) {
36 out.println("验证码为空");
37 } else {
38 if (validateC.equals(veryCode)) {
39 out.println("验证码正确");
40 } else {
41 out.println("验证码错误");
42 }
43 }
44 out.flush();
45 out.close();
46 }
47
48 }
49
changeImg.js
1 function changeImg() {
2 var imgSrc = $("#imgObj");
3 var src = imgSrc.attr("src");
4 imgSrc.attr("src", chgUrl(src));
5 //时间戳
6 //为了使每次生成图片不一致，即不让浏览器读缓存，所以需要加上时间戳
7 function chgUrl(url) {
8 var timestamp = (new Date()).valueOf();
9 urlurl = url.substring(0, 17);
10 if ((url.indexOf("?") >= 0)) {
11 urlurl = url + "&t=" + timestamp;
12 } else {
13 urlurl = url + "?t=" + timestamp;
14 }
15 return urlurl;
16 }
17 }
18 function isRightCode() {
19 var code = $("#veryCode").attr("value");
20
21 $.ajax({
22 type:"POST",
23 url:"ResultServlet",
24 data:"c="+code,
25 success:callback
26 });
27 }
28
29 function callback(data) {
30 $("#info").html(data);
31 }
32
ajax.jsp
1 <%@ page contentType="text/html;charset=UTF-8" language="java" %>
2 <html>
3 <head><title>ajax</title>
4 <script type="text/javascript" src="/js/jquery-1.2.6.js"></script>
5 <script type="text/javascript" src="/js/changImage.js"></script>
6 </head>
7 <body>
8 <input id="veryCode" name="veryCode" type="text"/>
9 <img id="imgObj" alt="" src="ImageServlet"/>
10 <a href="#" onclick="changeImg()">换一张</a>
11 <input type="button" value="验证" onclick="isRightCode()"/>
12 <div id="info"></div>
13 </body>
14 </html>
web.xml
1 <?xml version="1.0" encoding="UTF-8"?>
2 <web-app xmlns="http://java.sun.com/xml/ns/javaee"
3 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4 xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
5 http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
6 version="2.5">
7
8 <servlet>
9 <servlet-name>AjaxServlet</servlet-name>
10 <servlet-class>com.yu.AjaxServlet</servlet-class>
11 </servlet>
12 <servlet>
13 <servlet-name>ImageServlet</servlet-name>
14 <servlet-class>com.yu.ImageServlet</servlet-class>
15 <init-param>
16 <param-name>width</param-name>
17 <param-value>80</param-value>
18 </init-param>
19 <init-param>
20 <param-name>height</param-name>
21 <param-value>25</param-value>
22 </init-param>
23 <init-param>
24 <param-name>codeCount</param-name>
25 <param-value>4</param-value>
26 </init-param>
27 </servlet>
28 <servlet>
29 <servlet-name>ResultServlet</servlet-name>
30 <servlet-class>com.yu.ResultServlet</servlet-class>
31 </servlet>
32 <servlet-mapping>
33 <servlet-name>AjaxServlet</servlet-name>
34 <url-pattern>/AjaxServlet</url-pattern>
35 </servlet-mapping>
36 <servlet-mapping>
37 <servlet-name>ImageServlet</servlet-name>
38 <url-pattern>/ImageServlet</url-pattern>
39 </servlet-mapping>
40 <servlet-mapping>
41 <servlet-name>ResultServlet</servlet-name>
42 <url-pattern>/ResultServlet</url-pattern>
43 </servlet-mapping>
44 </web-app>