【Java】生成图形验证码

　　本章介绍一个能生成比较好看的图形验证码类

生成验证码工具类

　　

1 package com.util;
2
3 import java.awt.Color;
4 import java.awt.Font;
5 import java.awt.Graphics;
6 import java.awt.Graphics2D;
7 import java.awt.RenderingHints;
8 import java.awt.geom.AffineTransform;
9 import java.awt.image.BufferedImage;
10 import java.io.File;
11 import java.io.FileOutputStream;
12 import java.io.IOException;
13 import java.io.OutputStream;
14 import java.util.Arrays;
15 import java.util.Random;
16
17 import javax.imageio.ImageIO;
18
19
20 public class VerifyCodeUtils {
21
22     //使用到Algerian字体，系统里没有的话需要安装字体，字体只显示大写，去掉了1,0,i,o几个容易混淆的字符
23     public static final String VERIFY_CODES = "23456789ABCDEFGHJKLMNPQRSTUVWXYZ";
24     private static Random random = new Random();
25
26
27     /**
28      * 使用系统默认字符源生成验证码
29      * @param verifySize    验证码长度
30      * @return
31      */
32     public static String generateVerifyCode(int verifySize){
33         return generateVerifyCode(verifySize, VERIFY_CODES);
34     }
35
36     /**
37      * 使用指定源生成验证码
38      * @param verifySize    验证码长度
39      * @param sources   验证码字符源
40      * @return
41      */
42     public static String generateVerifyCode(int verifySize, String sources){
43         if(sources == null || sources.length() == 0){
44             sources = VERIFY_CODES;
45         }
46         int codesLen = sources.length();
47         Random rand = new Random(System.currentTimeMillis());
48         StringBuilder verifyCode = new StringBuilder(verifySize);
49         for(int i = 0; i < verifySize; i++){
50             verifyCode.append(sources.charAt(rand.nextInt(codesLen-1)));
51         }
52         return verifyCode.toString();
53     }
54
55     /**
56      * 生成随机验证码文件,并返回验证码值
57      * @param w
58      * @param h
59      * @param outputFile
60      * @param verifySize
61      * @return
62      * @throws IOException
63      */
64     public static String outputVerifyImage(int w, int h, File outputFile, int verifySize) throws IOException{
65         String verifyCode = generateVerifyCode(verifySize);
66         outputImage(w, h, outputFile, verifyCode);
67         return verifyCode;
68     }
69
70     /**
71      * 输出随机验证码图片流,并返回验证码值
72      * @param w
73      * @param h
74      * @param os
75      * @param verifySize
76      * @return
77      * @throws IOException
78      */
79     public static String outputVerifyImage(int w, int h, OutputStream os, int verifySize) throws IOException{
80         String verifyCode = generateVerifyCode(verifySize);
81         outputImage(w, h, os, verifyCode);
82         return verifyCode;
83     }
84
85     /**
86      * 生成指定验证码图像文件
87      * @param w
88      * @param h
89      * @param outputFile
90      * @param code
91      * @throws IOException
92      */
93     public static void outputImage(int w, int h, File outputFile, String code) throws IOException{
94         if(outputFile == null){
95             return;
96         }
97         File dir = outputFile.getParentFile();
98         if(!dir.exists()){
99             dir.mkdirs();
100         }
101         try{
102             outputFile.createNewFile();
103             FileOutputStream fos = new FileOutputStream(outputFile);
104             outputImage(w, h, fos, code);
105             fos.close();
106         } catch(IOException e){
107             throw e;
108         }
109     }
110
111     /**
112      * 输出指定验证码图片流
113      * @param w
114      * @param h
115      * @param os
116      * @param code
117      * @throws IOException
118      */
119     public static void outputImage(int w, int h, OutputStream os, String code) throws IOException{
120         int verifySize = code.length();
121         BufferedImage image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
122         Random rand = new Random();
123         Graphics2D g2 = image.createGraphics();
124         g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,RenderingHints.VALUE_ANTIALIAS_ON);
125         Color[] colors = new Color[5];
126         Color[] colorSpaces = new Color[] { Color.WHITE, Color.CYAN,
127                 Color.GRAY, Color.LIGHT_GRAY, Color.MAGENTA, Color.ORANGE,
128                 Color.PINK, Color.YELLOW };
129         float[] fractions = new float[colors.length];
130         for(int i = 0; i < colors.length; i++){
131             colors[i] = colorSpaces[rand.nextInt(colorSpaces.length)];
132             fractions[i] = rand.nextFloat();
133         }
134         Arrays.sort(fractions);
135
136         g2.setColor(Color.GRAY);// 设置边框色
137         g2.fillRect(0, 0, w, h);
138
139         Color c = getRandColor(200, 250);
140         g2.setColor(c);// 设置背景色
141         g2.fillRect(0, 2, w, h-4);
142
143         //绘制干扰线
144         Random random = new Random();
145         g2.setColor(getRandColor(160, 200));// 设置线条的颜色
146         for (int i = 0; i < 20; i++) {
147             int x = random.nextInt(w - 1);
148             int y = random.nextInt(h - 1);
149             int xl = random.nextInt(6) + 1;
150             int yl = random.nextInt(12) + 1;
151             g2.drawLine(x, y, x + xl + 40, y + yl + 20);
152         }
153
154         // 添加噪点
155         float yawpRate = 0.05f;// 噪声率
156         int area = (int) (yawpRate * w * h);
157         for (int i = 0; i < area; i++) {
158             int x = random.nextInt(w);
159             int y = random.nextInt(h);
160             int rgb = getRandomIntColor();
161             image.setRGB(x, y, rgb);
162         }
163
164         shear(g2, w, h, c);// 使图片扭曲
165
166         g2.setColor(getRandColor(100, 160));
167         int fontSize = h-4;
168         Font font = new Font("Algerian", Font.ITALIC, fontSize);
169         g2.setFont(font);
170         char[] chars = code.toCharArray();
171         for(int i = 0; i < verifySize; i++){
172             AffineTransform affine = new AffineTransform();
173             affine.setToRotation(Math.PI / 4 * rand.nextDouble() * (rand.nextBoolean() ? 1 : -1), (w / verifySize) * i + fontSize/2, h/2);
174             g2.setTransform(affine);
175             g2.drawChars(chars, i, 1, ((w-10) / verifySize) * i + 5, h/2 + fontSize/2 - 10);
176         }
177
178         g2.dispose();
179         ImageIO.write(image, "png", os);
180     }
181
182     private static Color getRandColor(int fc, int bc) {
183         if (fc > 255)
184             fc = 255;
185         if (bc > 255)
186             bc = 255;
187         int r = fc + random.nextInt(bc - fc);
188         int g = fc + random.nextInt(bc - fc);
189         int b = fc + random.nextInt(bc - fc);
190         return new Color(r, g, b);
191     }
192
193     private static int getRandomIntColor() {
194         int[] rgb = getRandomRgb();
195         int color = 0;
196         for (int c : rgb) {
197             color = color << 8;
198             color = color | c;
199         }
200         return color;
201     }
202
203     private static int[] getRandomRgb() {
204         int[] rgb = new int[3];
205         for (int i = 0; i < 3; i++) {
206             rgb[i] = random.nextInt(255);
207         }
208         return rgb;
209     }
210
211     private static void shear(Graphics g, int w1, int h1, Color color) {
212         shearX(g, w1, h1, color);
213         shearY(g, w1, h1, color);
214     }
215
216     private static void shearX(Graphics g, int w1, int h1, Color color) {
217
218         int period = random.nextInt(2);
219
220         boolean borderGap = true;
221         int frames = 1;
222         int phase = random.nextInt(2);
223
224         for (int i = 0; i < h1; i++) {
225             double d = (double) (period >> 1)
226                     * Math.sin((double) i / (double) period
227                             + (6.2831853071795862D * (double) phase)
228                             / (double) frames);
229             g.copyArea(0, i, w1, 1, (int) d, 0);
230             if (borderGap) {
231                 g.setColor(color);
232                 g.drawLine((int) d, i, 0, i);
233                 g.drawLine((int) d + w1, i, w1, i);
234             }
235         }
236
237     }
238
239     private static void shearY(Graphics g, int w1, int h1, Color color) {
240
241         int period = random.nextInt(40) + 10; // 50;
242
243         boolean borderGap = true;
244         int frames = 20;
245         int phase = 7;
246         for (int i = 0; i < w1; i++) {
247             double d = (double) (period >> 1)
248                     * Math.sin((double) i / (double) period
249                             + (6.2831853071795862D * (double) phase)
250                             / (double) frames);
251             g.copyArea(i, 0, 1, h1, 0, (int) d);
252             if (borderGap) {
253                 g.setColor(color);
254                 g.drawLine(i, (int) d, i, 0);
255                 g.drawLine(i, (int) d + h1, i, h1);
256             }
257
258         }
259     }
260     public static void main(String[] args) throws IOException{
261         File dir = new File("C:/Users/H__D/Desktop/");
262         int w = 200, h = 80;
263         String verifyCode = generateVerifyCode(4);
264         File file = new File(dir, verifyCode + ".jpg");
265         outputImage(w, h, file, verifyCode);
266     }
267 }

使用图形验证码

　　1、使用流程

　　　　


　　2、服务器端生成验证码servlet

1 package com.servlet;
2
3 import java.io.IOException;
4
5 import javax.servlet.ServletException;
6 import javax.servlet.http.HttpServlet;
7 import javax.servlet.http.HttpServletRequest;
8 import javax.servlet.http.HttpServletResponse;
9
10 import com.util.VerifyCodeUtils;
11
12
13 public class CreateCodeServlet extends HttpServlet {
14
15
16     @Override
17     protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
18         resp.setHeader("Pragma", "No-cache");
19         resp.setHeader("Cache-Control", "no-cache");
20         resp.setDateHeader("Expires", 0);
21         resp.setContentType("image/jpeg");
22
23         //生成随机字串
24         String verifyCode = VerifyCodeUtils.generateVerifyCode(4);
25         //存入会话session
26         req.getSession().setAttribute("CODE", verifyCode.toLowerCase());
27
28         //生成图片
29         int width = 100;//宽
30         int height = 40;//高
31         VerifyCodeUtils.outputImage(width, height, resp.getOutputStream(), verifyCode);
32
33     }
34
35     @Override
36     protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
37         // TODO Auto-generated method stub
38         doGet(req, resp);
39     }
40 }

　　3、服务器端验证验证码servlet

1 package com.servlet;
2
3 import java.io.IOException;
4
5 import javax.servlet.ServletException;
6 import javax.servlet.http.HttpServlet;
7 import javax.servlet.http.HttpServletRequest;
8 import javax.servlet.http.HttpServletResponse;
9
10 import com.util.VerifyCodeUtils;
11
12
13 public class VerifyCodeServlet extends HttpServlet {
14
15
16     @Override
17     protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
18
19         String code = req.getParameter("code");
20         String key = (String) req.getSession().getAttribute("CODE");
21         if(code != null && code.equalsIgnoreCase(key)){
22             req.getSession().removeAttribute("CODE");
23             resp.getWriter().println(true);
24         }else{
25             resp.getWriter().println(false);
26         }
27     }
28
29     @Override
30     protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
31         // TODO Auto-generated method stub
32         super.doGet(req, resp);
33     }
34 }

　　4、servet的注册，web.xml文件

1 <?xml version="1.0" encoding="UTF-8"?>
2 <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
3   <display-name>test-captcha</display-name>
4
5
6   <servlet>
7       <servlet-name>CreateCodeServlet</servlet-name>
8       <servlet-class>com.servlet.CreateCodeServlet</servlet-class>
9   </servlet>
10   <servlet-mapping>
11       <servlet-name>CreateCodeServlet</servlet-name>
12       <url-pattern>/createCode</url-pattern>
13   </servlet-mapping>
14
15    <servlet>
16       <servlet-name>VerifyCodeServlet</servlet-name>
17       <servlet-class>com.servlet.VerifyCodeServlet</servlet-class>
18   </servlet>
19   <servlet-mapping>
20       <servlet-name>VerifyCodeServlet</servlet-name>
21       <url-pattern>/verifyCode</url-pattern>
22   </servlet-mapping>
23
24
25   <welcome-file-list>
26     <welcome-file>index.jsp</welcome-file>
27   </welcome-file-list>
28 </web-app>

　　5、前端html文件

1 <%@ page language="java" contentType="text/html; charset=UTF-8"
2     pageEncoding="UTF-8"%>
3 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
4 <html>
5 <head>
6 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
7 <title>Insert title here</title>
8 </head>
9 <body>
10     <h2>测试验证码：</h2>
11     请输入验证码：<input type="text" name="code" /><img id="codeimg" src="${pageContext.request.contextPath }/createCode" onclick="changeImg()"><a href="javascript:void(0);" onclick="changeImg()">看不清，换一张</a>
12     <button onclick="submit()">提交</button>
13     <script type="text/javascript">
14
15         //改变验证码事件
16         function changeImg(){
17             var img = document.getElementById('codeimg');
18             img.src = "${pageContext.request.contextPath }/createCode?x=" + Math.floor(Math.random()*100)
19         }
20
21         //提交验证并验证验证码
22         function submit(){
23             var input = document.getElementsByTagName('input')[0];
24
25             //ajax提交
26             var xhr = new XMLHttpRequest();
27
28             xhr.onreadystatechange = function(){
29                 if(xhr.readyState == 4 && xhr.status == 200) {
30                     alert(xhr.responseText);
31                 }
32             }
33
34             xhr.open('get','${pageContext.request.contextPath }/verifyCode?code=' + input.value);
35             xhr.send(null);
36
37         }
38
39
40
41     </script>
42 </body>
43 </html>

　　6、使用浏览器打开页面访问，效果图如下：