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：
