【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

　　

 package com.util;

 import java.awt.Color;
 import java.awt.Font;
 import java.awt.Graphics;
 import java.awt.Graphics2D;
 import java.awt.RenderingHints;
 import java.awt.geom.AffineTransform;
 import java.awt.image.BufferedImage;
 import java.io.File;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.OutputStream;
 import java.util.Arrays;
 import java.util.Random;

 import javax.imageio.ImageIO;

 public class VerifyCodeUtils {

     //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
     public static final String VERIFY_CODES = "23456789ABCDEFGHJKLMNPQRSTUVWXYZ";
     private static Random random = new Random();

     /**
      * 使用系统默认字符源生成验证码
      * @param verifySize    验证码长度
      * @return
      */
     public static String generateVerifyCode(int verifySize){
         return generateVerifyCode(verifySize, VERIFY_CODES);
     }

     /**
      * 使用指定源生成验证码
      * @param verifySize    验证码长度
      * @param sources   验证码字符源
      * @return
      */
     public static String generateVerifyCode(int verifySize, String sources){
         if(sources == null || sources.length() == 0){
             sources = VERIFY_CODES;
         }
         int codesLen = sources.length();
         Random rand = new Random(System.currentTimeMillis());
         StringBuilder verifyCode = new StringBuilder(verifySize);
         for(int i = 0; i < verifySize; i++){
             verifyCode.append(sources.charAt(rand.nextInt(codesLen-1)));
         }
         return verifyCode.toString();
     }

     /**
      * 生成随机验证码文件,并返回验证码值
      * @param w
      * @param h
      * @param outputFile
      * @param verifySize
      * @return
      * @throws IOException
      */
     public static String outputVerifyImage(int w, int h, File outputFile, int verifySize) throws IOException{
         String verifyCode = generateVerifyCode(verifySize);
         outputImage(w, h, outputFile, verifyCode);
         return verifyCode;
     }

     /**
      * 输出随机验证码图片流,并返回验证码值
      * @param w
      * @param h
      * @param os
      * @param verifySize
      * @return
      * @throws IOException
      */
     public static String outputVerifyImage(int w, int h, OutputStream os, int verifySize) throws IOException{
         String verifyCode = generateVerifyCode(verifySize);
         outputImage(w, h, os, verifyCode);
         return verifyCode;
     }

     /**
      * 生成指定验证码图像文件
      * @param w
      * @param h
      * @param outputFile
      * @param code
      * @throws IOException
      */
     public static void outputImage(int w, int h, File outputFile, String code) throws IOException{
         if(outputFile == null){
             return;
         }
         File dir = outputFile.getParentFile();
         if(!dir.exists()){
             dir.mkdirs();
         }
         try{
             outputFile.createNewFile();
             FileOutputStream fos = new FileOutputStream(outputFile);
             outputImage(w, h, fos, code);
             fos.close();
         } catch(IOException e){
             throw e;
         }
     }

     /**
      * 输出指定验证码图片流
      * @param w
      * @param h
      * @param os
      * @param code
      * @throws IOException
      */
     public static void outputImage(int w, int h, OutputStream os, String code) throws IOException{
         int verifySize = code.length();
         BufferedImage image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
         Random rand = new Random();
         Graphics2D g2 = image.createGraphics();
         g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,RenderingHints.VALUE_ANTIALIAS_ON);
         Color[] colors = new Color[5];
         Color[] colorSpaces = new Color[] { Color.WHITE, Color.CYAN,
                 Color.GRAY, Color.LIGHT_GRAY, Color.MAGENTA, Color.ORANGE,
                 Color.PINK, Color.YELLOW };
         float[] fractions = new float[colors.length];
         for(int i = 0; i < colors.length; i++){
             colors[i] = colorSpaces[rand.nextInt(colorSpaces.length)];
             fractions[i] = rand.nextFloat();
         }
         Arrays.sort(fractions);

         g2.setColor(Color.GRAY);// 设置边框色
         g2.fillRect(0, 0, w, h);

         Color c = getRandColor(200, 250);
         g2.setColor(c);// 设置背景色
         g2.fillRect(0, 2, w, h-4);

         //绘制干扰线
         Random random = new Random();
         g2.setColor(getRandColor(160, 200));// 设置线条的颜色
         for (int i = 0; i < 20; i++) {
             int x = random.nextInt(w - 1);
             int y = random.nextInt(h - 1);
             int xl = random.nextInt(6) + 1;
             int yl = random.nextInt(12) + 1;
             g2.drawLine(x, y, x + xl + 40, y + yl + 20);
         }

         // 添加噪点
         float yawpRate = 0.05f;// 噪声率
         int area = (int) (yawpRate * w * h);
         for (int i = 0; i < area; i++) {
             int x = random.nextInt(w);
             int y = random.nextInt(h);
             int rgb = getRandomIntColor();
             image.setRGB(x, y, rgb);
         }

         shear(g2, w, h, c);// 使图片扭曲

         g2.setColor(getRandColor(100, 160));
         int fontSize = h-4;
         Font font = new Font("Algerian", Font.ITALIC, fontSize);
         g2.setFont(font);
         char[] chars = code.toCharArray();
         for(int i = 0; i < verifySize; i++){
             AffineTransform affine = new AffineTransform();
             affine.setToRotation(Math.PI / 4 * rand.nextDouble() * (rand.nextBoolean() ? 1 : -1), (w / verifySize) * i + fontSize/2, h/2);
             g2.setTransform(affine);
             g2.drawChars(chars, i, 1, ((w-10) / verifySize) * i + 5, h/2 + fontSize/2 - 10);
         }

         g2.dispose();
         ImageIO.write(image, "png", os);
     }

     private static Color getRandColor(int fc, int bc) {
         if (fc > 255)
             fc = 255;
         if (bc > 255)
             bc = 255;
         int r = fc + random.nextInt(bc - fc);
         int g = fc + random.nextInt(bc - fc);
         int b = fc + random.nextInt(bc - fc);
         return new Color(r, g, b);
     }

     private static int getRandomIntColor() {
         int[] rgb = getRandomRgb();
         int color = 0;
         for (int c : rgb) {
             color = color << 8;
             color = color | c;
         }
         return color;
     }

     private static int[] getRandomRgb() {
         int[] rgb = new int[3];
         for (int i = 0; i < 3; i++) {
             rgb[i] = random.nextInt(255);
         }
         return rgb;
     }

     private static void shear(Graphics g, int w1, int h1, Color color) {
         shearX(g, w1, h1, color);
         shearY(g, w1, h1, color);
     }

     private static void shearX(Graphics g, int w1, int h1, Color color) {

         int period = random.nextInt(2);

         boolean borderGap = true;
         int frames = 1;
         int phase = random.nextInt(2);

         for (int i = 0; i < h1; i++) {
             double d = (double) (period >> 1)
                     * Math.sin((double) i / (double) period
                             + (6.2831853071795862D * (double) phase)
                             / (double) frames);
             g.copyArea(0, i, w1, 1, (int) d, 0);
             if (borderGap) {
                 g.setColor(color);
                 g.drawLine((int) d, i, 0, i);
                 g.drawLine((int) d + w1, i, w1, i);
             }
         }

     }

     private static void shearY(Graphics g, int w1, int h1, Color color) {

         int period = random.nextInt(40) + 10; // 50;

         boolean borderGap = true;
         int frames = 20;
         int phase = 7;
         for (int i = 0; i < w1; i++) {
             double d = (double) (period >> 1)
                     * Math.sin((double) i / (double) period
                             + (6.2831853071795862D * (double) phase)
                             / (double) frames);
             g.copyArea(i, 0, 1, h1, 0, (int) d);
             if (borderGap) {
                 g.setColor(color);
                 g.drawLine(i, (int) d, i, 0);
                 g.drawLine(i, (int) d + h1, i, h1);
             }

         }
     }
     public static void main(String[] args) throws IOException{
         File dir = new File("C:/Users/H__D/Desktop/");
         int w = 200, h = 80;
         String verifyCode = generateVerifyCode(4);
         File file = new File(dir, verifyCode + ".jpg");
         outputImage(w, h, file, verifyCode);
     }
 }

使用图形验证码

　　1、使用流程

　　　　

　　2、服务器端生成验证码servlet

 package com.servlet;

 import java.io.IOException;

 import javax.servlet.ServletException;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;

 import com.util.VerifyCodeUtils;

 public class CreateCodeServlet extends HttpServlet {

     @Override
     protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
         resp.setHeader("Pragma", "No-cache");
         resp.setHeader("Cache-Control", "no-cache");
         resp.setDateHeader("Expires", 0);
         resp.setContentType("image/jpeg");  

         //生成随机字串
         String verifyCode = VerifyCodeUtils.generateVerifyCode(4);
         //存入会话session
         req.getSession().setAttribute("CODE", verifyCode.toLowerCase());  

         //生成图片
         int width = 100;//宽
         int height = 40;//高
         VerifyCodeUtils.outputImage(width, height, resp.getOutputStream(), verifyCode);  

     }

     @Override
     protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
         // TODO Auto-generated method stub
         doGet(req, resp);
     }
 }

　　3、服务器端验证验证码servlet

 package com.servlet;

 import java.io.IOException;

 import javax.servlet.ServletException;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;

 import com.util.VerifyCodeUtils;

 public class VerifyCodeServlet extends HttpServlet {

     @Override
     protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

         String code = req.getParameter("code");
         String key = (String) req.getSession().getAttribute("CODE");
         if(code != null && code.equalsIgnoreCase(key)){
             req.getSession().removeAttribute("CODE");
             resp.getWriter().println(true);
         }else{
             resp.getWriter().println(false);
         }
     }

     @Override
     protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
         // TODO Auto-generated method stub
         super.doGet(req, resp);
     }
 }

　　4、servet的注册，web.xml文件

 <?xml version="1.0" encoding="UTF-8"?>
 <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">
   <display-name>test-captcha</display-name>

   <servlet>
       <servlet-name>CreateCodeServlet</servlet-name>
       <servlet-class>com.servlet.CreateCodeServlet</servlet-class>
   </servlet>
   <servlet-mapping>
       <servlet-name>CreateCodeServlet</servlet-name>
       <url-pattern>/createCode</url-pattern>
   </servlet-mapping>

    <servlet>
       <servlet-name>VerifyCodeServlet</servlet-name>
       <servlet-class>com.servlet.VerifyCodeServlet</servlet-class>
   </servlet>
   <servlet-mapping>
       <servlet-name>VerifyCodeServlet</servlet-name>
       <url-pattern>/verifyCode</url-pattern>
   </servlet-mapping>

   <welcome-file-list>
     <welcome-file>index.jsp</welcome-file>
   </welcome-file-list>
 </web-app>

　　5、前端html文件

 <%@ page language="java" contentType="text/html; charset=UTF-8"
     pageEncoding="UTF-8"%>
 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
 <html>
 <head>
 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
 <title>Insert title here</title>
 </head>
 <body>
     <h2>测试验证码：</h2>
     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>
     <button onclick="submit()">提交</button>
     <script type="text/javascript">

         //改变验证码事件
         function changeImg(){
             var img = document.getElementById('codeimg');
             img.src = "${pageContext.request.contextPath }/createCode?x=" + Math.floor(Math.random()*100)
         }

         //提交验证并验证验证码
         function submit(){
             var input = document.getElementsByTagName('input')[0];

             //ajax提交
             var xhr = new XMLHttpRequest();

             xhr.onreadystatechange = function(){
                 if(xhr.readyState == 4 && xhr.status == 200) {
                     alert(xhr.responseText);
                 }
             }

             xhr.open('get','${pageContext.request.contextPath }/verifyCode?code=' + input.value);
             xhr.send(null);

         }

     </script>
 </body>
 </html>

　　6、使用浏览器打开页面访问，效果图如下：