SpringMVC下获取验证码实例详解
SpringMVC下获取验证码实例详解 前言: 1.用户一开始登录的时候,不建议出现验证码,这一点在很多网站上已经体现的很好了,只有当用户连续输错三次或者以上才会要求用户输入验证码. 2.记录用户输错次数最好不要使用 session 来记录,因为 session 是跟客户端浏览器会话有关的,如果用重启浏览器或者换新的浏览器再来登录或者试错,就是新的回话了,原来记录的错误次数就失效了. 建议此处采用缓存机制来实现,简单处理就是采用 Map<用户登录id,错误次数> 来实现,如果有多台服务器负载的话,就需要采用另外的缓存机制,比如采用 Redis. 3.当用户输入完用户名以后,就需要用登录名进行判断,是否需要进行验证码校验. 4.生成的验证码与 session 绑定,是否需要校验验证码,要根据用户规定时间内失败的次数来判断. 原生的 servlet 可以直接 write 图片到客户端. 但是刚用 springMVC 的童鞋可能不知道怎么在此框架下返回图片. 其实在本质上用 spring 返回图片跟用 servlet 是一样的。都是使用的 HttpServletResponse 来返回图片. springMVC 的 controller 里获取验证码的方法 /** * 生成验证码 * @param request * @param response */ @RequestMapping(value = "login/getVerifyCode") public void getVerifyCode(HttpServletRequest request,HttpServletResponse response){ response.setHeader("Pragma","No-cache"); response.setHeader("Cache-Control","no-cache"); response.setDateHeader("Expires",0); response.setContentType("image/jpeg"); //生成随机字符串 String verifyCode = VerifyCodeUtils.generateVerifyCode(4); //存入Session,此处可以根据自己的需求 HttpSession session = request.getSession(); session.setAttribute("verifyCode",verifyCode); //生成图片 int w = 100,h = 35; try { //将图片写入到 response 的输出流即可将图片返回到客户端了 VerifyCodeUtils.outputImage(w,h,response.getOutputStream(),verifyCode); } catch (IOException e) { logger.error("生成验证码失败,Cause by: {}",e.getMessage(),e); } } 生成验证码图片的类 网上找到的一个,还不错. import javax.imageio.ImageIO; import java.awt.*; 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; /** * 生成图片流 * @Description: Created by zcqshine on 2017/5/18. */ public class VerifyCodeUtils { private 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.trim().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(); } /** * 输出随机验证码图片流,并返回验证码值 * @param w * @param h * @param outputFile * @param verifySize * @return */ public static String outputVerifyImage(int w,int h,File outputFile,int verifySize) throws IOException{ String verifyCode = generateVerifyCode(verifySize); outputImage(w,outputFile,verifyCode); return verifyCode; } /** * 生成指定验证码图像文件 * @param w * @param h * @param outputFile * @param verifyCode * @throws IOException */ public static void outputImage(int w,String verifyCode) 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,fos,verifyCode); fos.close(); } catch (IOException e) { throw e; } } public static void outputImage(int w,OutputStream os,String code) throws IOException{ int verifySize = code.length(); BufferedImage image = new BufferedImage(w,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,w,h); Color c = getRandColor(200,250); g2.setColor(c); //设置背景色 g2.fillRect(0,2,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,rgb); } shear(g2,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,"jpg",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,color); } private static void shearX(Graphics g,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,(int) d,0); if (borderGap) { g.setColor(color); g.drawLine((int) d,i); g.drawLine((int) d + w1,i); } } } private static void shearY(Graphics g,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,(int) d); if (borderGap) { g.setColor(color); g.drawLine(i,0); g.drawLine(i,(int) d + h1,h1); } } } public static void main(String[] args) { File dir = new File("/Users/zcqshine/Downloads/test"); int w = 200,h= 80; for (int i = 0; i< 50; i++){ String verifyCode = generateVerifyCode(4); File file = new File(dir,verifyCode + ".jpg"); try { outputImage(w,file,verifyCode); } catch (IOException e) { e.printStackTrace(); } } } } 感谢阅读,希望能帮助到大家,谢谢大家对本站的支持!如有疑问请留言或到本站社区交流讨论,大家共同进步! 您可能感兴趣的文章:
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