A, BufferedImage class presentation
CAPTCHA image generation mainly uses a BufferedImage class, the following:
Create a DrawImage Servlet, used to generate the CAPTCHA image
1 package wxb.response.study;
2 import java.awt.Color;
3 import java.awt.Font;
4 import java.awt.Graphics;
5 import java.awt.Graphics2D;
6 import java.awt.image.BufferedImage;
7 import java.io.IOException;
8 import java.util.Random;
9 import javax.imageio.ImageIO;
10 import javax.servlet.ServletException;
11 import javax.servlet.http.HttpServlet;
12 import javax.servlet.http.HttpServletRequest;
13 import javax.servlet.http.HttpServletResponse;
14 /**
15 * 生成随机图片，用来作为验证码
16 */
17 public class DrawImage extends HttpServlet {
Private static serialVersionUID = Final 18 is 3038623696184546092L Long;
. 31 1 // create a picture in memory
19
20 public static final int WIDTH = 120 ; // generated image width
21 public static final int HEIGHT = 30 ; // generated image height
22 is
23 is the doGet public void (the HttpServletRequest Request, the HttpServletResponse Response)
24 throws ServletException, IOException {
this.doPost 25 (Request, Response);
26 is}
27
28 public void the doPost (the HttpServletRequest Request, the HttpServletResponse Response)
29 throws ServletException, IOException {
30 String createTypeFlag = request.getParameter ( "createTypeFlag"); // passed by the client receiving createTypeFlag identification
32 the BufferedImage the BufferedImage new new BI = (WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);
. 33 is obtained image // 2
34 is bi.getGraphics Graphics G = ();
35. 3 // set back color image.
36 setBackground (G);
.. 4 // 37 [image provided border
38 is the setBorder (G);
.. 5 39 // draw lines on the interference image
40 drawRandomLine (G);
.. 6 // 41 is written in the random number image
42 // String random = drawRandomNum (( Graphics2D) g, "ch "); // Chinese codes generated image
43 // String random = drawRandomNum (( Graphics2D) g," nl "); // a combination of letters and generating a digital image codes
44 // String random = drawRandomNum (( Graphics2D) g, "n"); // pure digital codes generated image
45 // String random = drawRandomNum (( Graphics2D) g, "l"); // pure letter codes generated image
46 String random = drawRandomNum ((Graphics2D ) g, createTypeFlag); // the createTypeFlag identifier passed by the client to generate image codes
47 @ 7 there will be a random number in the session.
48 Request.getSession () the setAttribute ( "checkcode." ,random);
49 @ 8 is provided in response to the first notification image browser to open in the form of
50 response.setContentType ( "image / jpeg" ); // equivalent to response.setHeader ( "the Content-the Type", "Image / JPEG");
51 is // set the response header 9 do not control the browser cache
52 is. response.setDateHeader ( "expries", -1);
53 is response.setHeader ( "the cache-control", "cache-NO");
54 is response.setHeader ( "Pragma "," Cache-NO ");
. 55 // 10 addressed picture browser
56 is ImageIO.write (BI," JPG ", response.getOutputStream ());
57 is}
58
59 / **
67 g.fillRect (0, 0, WIDTH, HEIGHT);
68}
60 * set the background color image
61 is G * @param
62 is * /
Private void setBackground 63 is (Graphics G) {
64 // set the color
65 g.setColor (Color.WHITE);
66 // filling region
69
70 / *
71 * set the picture frame
72 * @param G
73 is * /
74 Private the setBorder void (Graphics G) {
75 // set the border color
76 g.setColor (Color.BLUE);
77 // frame region
78 g.drawRect (. 1,. 1, WIDTH - 2, HEIGHT - 2);
79}
80
81 / **
82 * Videos random lines on the image
83 * @param G
84 * /
85 Private void drawRandomLine (Graphics G) {
86 // set the color
87 g.setColor (Color.GREEN);
// Set the number of lines 88 and draw lines
89 for (int I = 0; I <. 5; I ++) {
90 int new new X1 = the Random () the nextInt (WIDTH);.
. Int Y1 = new new 91 is the Random () the nextInt ( HEIGHT);
105 * /
The Random new new int X2 = 92 () the nextInt (WIDTH);.
93 Y2 = new new int the Random () the nextInt (HEIGHT);.
94 g.drawLine (X1, Y1, X2, Y2);
95}
96}
97
98 / * *
99 * Videos random character
100 * @param G
101 * @param createTypeFlag
102 @return *
103 * String is a variable parameter createTypeFlag ...,
104 * Java1.5 adds new features: variable parameters: parameters that apply to a unknown number, type determination of the case, java processing the array as a variable parameter. NOTE: The last parameter must be in a variable
109 // set the font
110 g.setFont ( new Font ( "Arial", Font.BOLD, 20));
String Private drawRandomNum 106 (the Graphics2D G, ... String createTypeFlag) {
107 // set the color
108 g.setColor (Color.RED);
111 // commonly used Chinese characters
112 String baseChineseChar = "\u7684\u4e00\u4e86\u662f\u6211\u4e0d\u5728\u4eba\u4eec\u6709\u6765\u4ed6\u8fd9\u4e0a\u7740\u4e2a\u5730\u5230\u5927\u91cc\u8bf4\u5c31\u53bb\u5b50\u5f97\u4e5f\u548c\u90a3\u8981\u4e0b\u770b\u5929\u65f6\u8fc7\u51fa\u5c0f\u4e48\u8d77\u4f60\u90fd\u628a\u597d\u8fd8\u591a\u6ca1\u4e3a\u53c8\u53ef\u5bb6\u5b66\u53ea\u4ee5\u4e3b\u4f1a\u6837\u5e74\u60f3\u751f\u540c\u8001\u4e2d\u5341\u4ece\u81ea\u9762\u524d\u5934\u9053\u5b83\u540e\u7136\u8d70\u5f88\u50cf\u89c1\u4e24\u7528\u5979\u56fd\u52a8\u8fdb\u6210\u56de\u4ec0\u8fb9\u4f5c\u5bf9\u5f00\u800c\u5df1\u4e9b\u73b0\u5c71\u6c11\u5019\u7ecf\u53d1\u5de5\u5411\u4e8b\u547d\u7ed9\u957f\u6c34\u51e0\u4e49\u4e09\u58f0\u4e8e\u9ad8\u624b\u77e5\u7406\u773c\u5fd7\u70b9\u5fc3\u6218\u4e8c\u95ee\u4f46\u8eab\u65b9\u5b9e\u5403\u505a\u53eb\u5f53\u4f4f\u542c\u9769\u6253\u5462\u771f\u5168\u624d\u56db\u5df2\u6240\u654c\u4e4b\u6700\u5149\u4ea7\u60c5\u8def\u5206\u603b\u6761\u767d\u8bdd\u4e1c\u5e2d\u6b21\u4eb2\u5982\u88ab\u82b1\u53e3\u653e\u513f\u5e38\u6c14\u4e94\u7b2c\u4f7f\u5199\u519b\u5427\u6587\u8fd0\u518d\u679c\u600e\u5b9a\u8bb8\u5feb\u660e\u884c\u56e0\u522b\u98de\u5916\u6811\u7269\u6d3b\u90e8\u95e8\u65e0\u5f80\u8239\u671b\u65b0\u5e26\u961f\u5148\u529b\u5b8c\u5374\u7ad9\u4ee3\u5458\u673a\u66f4\u4e5d\u60a8\u6bcf\u98ce\u7ea7\u8ddf\u7b11\u554a\u5b69\u4e07\u5c11\u76f4\u610f\u591c\u6bd4\u9636\u8fde\u8f66\u91cd\u4fbf\u6597\u9a6c\u54ea\u5316\u592a\u6307\u53d8\u793e\u4f3c\u58eb\u8005\u5e72\u77f3\u6ee1\u65e5\u51b3\u767e\u539f\u62ff\u7fa4\u7a76\u5404\u516d\u672c\u601d\u89e3\u7acb\u6cb3\u6751\u516b\u96be\u65e9\u8bba\u5417\u6839\u5171\u8ba9\u76f8\u7814\u4eca\u5176\u4e66\u5750\u63a5\u5e94\u5173\u4fe1\u89c9\u6b65\u53cd\u5904\u8bb0\u5c06\u5343\u627e\u4e89\u9886\u6216\u5e08\u7ed3\u5757\u8dd1\u8c01\u8349\u8d8a\u5b57\u52a0\u811a\u7d27\u7231\u7b49\u4e60\u9635\u6015\u6708\u9752\u534a\u706b\u6cd5\u9898\u5efa\u8d76\u4f4d\u5531\u6d77\u4e03\u5973\u4efb\u4ef6\u611f\u51c6\u5f20\u56e2\u5c4b\u79bb\u8272\u8138\u7247\u79d1\u5012\u775b\u5229\u4e16\u521a\u4e14\u7531\u9001\u5207\u661f\u5bfc\u665a\u8868\u591f\u6574\u8ba4\u54cd\u96ea\u6d41\u672a\u573a\u8be5\u5e76\u5e95\u6df1\u523b\u5e73\u4f1f\u5fd9\u63d0\u786e\u8fd1\u4eae\u8f7b\u8bb2\u519c\u53e4\u9ed1\u544a\u754c\u62c9\u540d\u5440\u571f\u6e05\u9633\u7167\u529e\u53f2\u6539\u5386\u8f6c\u753b\u9020\u5634\u6b64\u6cbb\u5317\u5fc5\u670d\u96e8\u7a7f\u5185\u8bc6\u9a8c\u4f20\u4e1a\u83dc\u722c\u7761\u5174\u5f62\u91cf\u54b1\u89c2\u82e6\u4f53\u4f17\u901a\u51b2\u5408\u7834\u53cb\u5ea6\u672f\u996d\u516c\u65c1\u623f\u6781\u5357\u67aa\u8bfb\u6c99\u5c81\u7ebf\u91ce\u575a\u7a7a\u6536\u7b97\u81f3\u653f\u57ce\u52b3\u843d\u94b1\u7279\u56f4\u5f1f\u80dc\u6559\u70ed\u5c55\u5305\u6b4c\u7c7b\u6e10\u5f3a\u6570\u4e61\u547c\u6027\u97f3\u7b54\u54e5\u9645\u65e7\u795e\u5ea7\u7ae0\u5e2e\u5566\u53d7\u7cfb\u4ee4\u8df3\u975e\u4f55\u725b\u53d6\u5165\u5cb8\u6562\u6389\u5ffd\u79cd\u88c5\u9876\u6025\u6797\u505c\u606f\u53e5\u533a\u8863\u822c\u62a5\u53f6\u538b\u6162\u53d4\u80cc\u7ec6";
A combination of numbers and letters 113 //
114 baseNumLetter String = "0123456789ABCDEFGHJKLMNOPQRSTUVWXYZ";
115 // pure digital
1 16 BaseNum String = "0123456789";
117 // pure letters
1 18 baseLetter String = "ABCDEFGHJKLMNOPQRSTUVWXYZ";
119 // createTypeFlag [0] = = null indicates no arguments are passed
120 IF (createTypeFlag.length> null && 0! = createTypeFlag [0]) {
121 IF (createTypeFlag [0] .equals ( "CH")) {
122 // taken characters
123 return createRandomChar (g , baseChineseChar);
124} the else IF (createTypeFlag [0] .equals ( "NL")) {
combination of numbers and letters taken // 125 of
126 return createRandomChar (g,baseNumLetter);
IF the else} 127 (createTypeFlag [0] .equals ( "n-")) {
128 // Capture digital
129 return createRandomChar (G, BaseNum);
130. IF the else} (createTypeFlag [0] .equals ( "L")) {
131 // taken letters
132 return createRandomChar (G, baseLetter);
133}
134} the else {
135 // default combination of numbers and letters taken
136 return createRandomChar (G, baseNumLetter);
137}
138
139 return "";
140}
141 is
142 / **
143 * create a random character
144 * @param G
145 * @param baseChar
146 * @return random characters
* 147/
148 String Private createRandomChar (the Graphics2D G, String baseChar) {
149 the StringBuffer the StringBuffer new new SB = ();
150 X = int. 5;
151 CH String = "";
152 // control word
153 for (int i = 0; I <. 4; I ++) {
154 // set the font rotational angle of
155 new new int the Random Degree = (.) the nextInt ()% 30;
156 CH = baseChar.charAt (new new the Random (). the nextInt (baseChar.length ())) + "";
157 sb.append (CH);
158 // forward angle
159 g.rotate (Degree Math.PI * / 180 [, X, 20 is);
160. g.drawString (CH, X, 20 is);
161 / / reverse angle
162 g.rotate (-degree * Math.PI / 180 , x, 20);
163 x += 30;
164 }
165 return sb.toString();
166 }
167 }
Second, the use CAPTCHA image form in Form
1 <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
2 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
3 <html>
4 <head>
5 <title>在Form表单中使用验证码</title>
6 <script type="text/javascript">
7 //刷新验证码
8 function changeImg(){
9 document.getElementById("validateCodeImg").src="${pageContext.request.contextPath}/servlet/DrawImage?"+Math.random();
10 }
11 </script>
12 </head>
13
14 <body>
15 <form action="${pageContext.request.contextPath}/servlet/CheckServlet" method="post">
16 验证码：<input type="text" name="validateCode"/>
17 <img alt = "codes see, for a" the src = "$ {pageContext.request.contextPath} / the servlet / the DrawImage" ID = "validateCodeImg" the onclick = "changeImg ()">
18 is <the href = A "javascript: void (0)" onclick = "changeImg ()"> clear, for a </a>
. 19 a
20 is <INPUT type = "Submit" value = "submit">
21 is </ form >
22 is </ body>
23 is </ HTML>
DrawImage Servlet can be generated in addition to alphanumeric codes combined image can also be generated characters, purely digital, purely letters verification picture, only needs to pass a good agreement DrawImage Servlet can generate an identifier parameter, as follows below:
1 <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
2 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
3 <html>
4 <head>
5 <title>在Form表单中使用验证码</title>
6 <script type="text/javascript">
7 //刷新验证码
8 function changeImg(obj,createTypeFlag){
9 document.getElementById(obj.id).src="${pageContext.request.contextPath}/servlet/DrawImage?createTypeFlag="+createTypeFlag+"&"+Math.random();
10 }
11 </script>
12 </head>
13
14 <body>
15 <form action="${pageContext.request.contextPath}/servlet/CheckServlet" method="post">
16 alphanumeric codes: <type INPUT = "text" name = "validateCode" />
. 17 <IMG Alt = "codes see, for a" src = "$ {pageContext.request.contextPath} / servlet / the DrawImage "ID =" validateCodeImg1 "the onclick =" changeImg (the this, 'NL') ">
18 is a
. 19 Chinese codes: <INPUT type =" text "name =" validateCode "/>
20 is <IMG Alt = "codes see, for a" the src = "$ {pageContext.request.contextPath} / the servlet / the DrawImage? createTypeFlag = CH" ID = "validateCodeImg2" the onclick = "changeImg (the this, 'CH')">
21 is a
22 is English codes: <INPUT type = "text" name = "validateCode" />
23 is <img alt = "codes see, for a" src = "$ {pageContext.request.contextPath} / servlet / DrawImage? createTypeFlag = l" id = "validateCodeImg3" onclick = "changeImg (this, 'l') ">
24 a
25 digital codes: <INPUT type = "text" name = "validateCode" />
26 is <IMG Alt = "codes see, for a" src = "$ {pageContext.request.contextPath} / servlet / DrawImage ? = n-createTypeFlag "ID =" validateCodeImg4 "the onclick =" changeImg (the this, 'n-') ">
27 a
28 <INPUT type =" Submit "value =" submit ">
29 </ form>
30 </ body>
31 is </ HTML>
Third, form submission server side form up processing codes
Package wxb.response.study. 1;
2 Import java.io.IOException;
. 3 Import javax.servlet.ServletException;
. 4 Import the javax.servlet.http.HttpServlet;
. 5 Import the javax.servlet.http.HttpServletRequest;
. 6 Import the javax.servlet. http.HttpServletResponse;
. 7 / **
. 8 * @author GaCl
. 9 * after the server receives the authentication code processing
10 * /
. 11 CheckServlet the extends the HttpServlet {public class
12 is the doGet public void (the HttpServletRequest Request, the HttpServletResponse Response)
13 is ServletException throws, IOException {
14 String clientCheckcode = request.getParameter ( "validateCode"); // receiving client browser to submit up codes
15 String serverCheckcode = (String) request.getSession () getAttribute ( "checkcode");. // session authentication code from the server side
16 if (clientCheckcode.equals (serverCheckcode)) {// the client and server codes comparison side validation, if they are equal, then validated by
17 System.out.println ( "PIN verified!");
18 is} {the else
. 19 System.out.println ( "PIN verification failed!");
20}
21 }
22 is
23 is the doPost public void (the HttpServletRequest Request, the HttpServletResponse Response)
24 throws ServletException, IOException {
25 the doGet (Request, Response);
26 is}
27
28}