Java类

public class RandomValidateCode {  public static final String RANDOMCODEKEY = "randomcode_key";//放到session中的key  private Random random = new Random();  private String randString = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";//随机产生的字符串  private int width = 80;//图片宽  private int height = 26;//图片高  private int lineSize = 40;//干扰线数量  private int stringNum = 4;//随机产生字符数量  /**   * 生成随机图片   */  public void getRandcode(HttpServletRequest request,              HttpServletResponse response) {    HttpSession session = request.getSession();    //BufferedImage类是具有缓冲区的Image类,Image类是用于描述图像信息的类    BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_BGR);    //产生Image对象的Graphics对象,改对象可以在图像上进行各种绘制操作    Graphics g = image.getGraphics();    g.fillRect(0, 0, width, height);    g.setFont(new Font("Times New Roman",Font.ROMAN_BASELINE,18));    g.setColor(getRandColor(160, 200));    //绘制干扰线    for(int i=0;i<=lineSize;i++){      drowLine(g);    }    //绘制随机字符    String randomString = "";    for(int i=1;i<=stringNum;i++){      randomString=drowString(g,randomString,i);    }    session.removeAttribute(RANDOMCODEKEY);    session.setAttribute(RANDOMCODEKEY, randomString);    g.dispose();    try {      //将内存中的图片通过流动形式输出到客户端      ImageIO.write(image, "JPEG", response.getOutputStream());    } catch (Exception e) {      e.printStackTrace();    }  }  /*   * 获得字体   */  private Font getFont(){    return new Font("Fixedsys",Font.CENTER_BASELINE,18);  }  /*   * 获得颜色   */  private Color getRandColor(int fc,int bc){    if(fc > 255)      fc = 255;    if(bc > 255)      bc = 255;    int r = fc + random.nextInt(bc-fc-16);    int g = fc + random.nextInt(bc-fc-14);    int b = fc + random.nextInt(bc-fc-18);    return new Color(r,g,b);  }  /*   * 绘制字符串   */  private String drowString(Graphics g,String randomString,int i){    g.setFont(getFont());    g.setColor(new Color(random.nextInt(101),random.nextInt(111),random.nextInt(121)));    String rand = String.valueOf(getRandomString(random.nextInt(randString.length())));    randomString +=rand;    g.translate(random.nextInt(3), random.nextInt(3));    g.drawString(rand, 13*i, 16);    return randomString;  }  /*   * 绘制干扰线   */  private void drowLine(Graphics g){    int x = random.nextInt(width);    int y = random.nextInt(height);    int xl = random.nextInt(13);    int yl = random.nextInt(15);    g.drawLine(x, y, x+xl, y+yl);  }  /*   * 获取随机的字符   */  public String getRandomString(int num){    return String.valueOf(randString.charAt(num));  }}

Controller

@RequestMapping(value="/checkCode")  public void checkCode(HttpServletRequest request, HttpServletResponse response)      throws ServletException, IOException {    //设置相应类型,告诉浏览器输出的内容为图片    response.setContentType("image/jpeg");    //设置响应头信息，告诉浏览器不要缓存此内容    response.setHeader("pragma", "no-cache");    response.setHeader("Cache-Control", "no-cache");    response.setDateHeader("Expire", 0);    RandomValidateCode randomValidateCode = new RandomValidateCode();    try {      randomValidateCode.getRandcode(request, response);//输出图片方法    } catch (Exception e) {      e.printStackTrace();    }  }

前端jsp页面表单，显示验证码