SpringMVC下获取验证码实例详解

php  /  管理员 发布于 8年前   326

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,h,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, int h, File outputFile, 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, h, fos, verifyCode);      fos.close();    } catch (IOException e) {      throw e;    }  }  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, "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, 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) {    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, h, file, verifyCode);      } catch (IOException e) {        e.printStackTrace();      }    }  }}

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