关于jsp开发验证码的实现-蒲公英云

前言，今天要写的是jsp开发时，需要的验证码功能。

1，实现验证码有很多方式，现在还有插件可以使用，今天主要讲的是通过代码实现验证码的功能

2，开始

1）首先我们要在前端写好验证码显示的区域

<div>
      验证码：<img  src="<%=request.getContextPath() %>/base2/validate" alt="验证码" id="image" />
      <a href="javascript:reload();"><label>换一张</label></a><br>
      <input type="text" name="yanzhengma"  id="yanzhengma" class="form-control" placeholder="验证码(忽略大小写)" onblur="validateCode();" />
      <label id="spans"></label>
</div>

2）然后我们需要写好JavaScript,我们需要用到它去获得验证码，以及刷新验证码功能

<script type="text/javascript">
 //-----------------------这个函数主要用来刷新验证码------------------------------------
   function reload(){
      $("#image").attr('src','<%=request.getContextPath()%>/base2/validate?date='+new Date().getTime());
      $("#checkcode").val("");   // 将验证码清空
    }
//------------------------这个函数用来校验验证码--------------------------
    function yanzhengma() {
      var spans=document.getElementById("spans");
      var texts=document.getElementById("yanzhengma").value;
      if(texts.length<=0){
        spans.innerHTML="请输入输入验证码";
        spans.style.background="red";
        return false;
      }else{
        $.ajax({
          Type:"POST",
          url:"base2/check",
          data:{"texts":texts},
          success:function (data) {
            var booleans=data.boo;
            if (booleans == "false") {
              spans.innerHTML = "验证码输入错误";
              spans.style.background = "red";
              reload();  //验证失败后需要更换验证码
              texts = ""; // 将验证码清空
              return false;
            } else {
              spans.innerHTML = "验证码输入正确";
              spans.style.background = "green";
              return true;
            }
          }
        });
      }
    }
</script>

3）第三步当然就是制作验证码了，我使用的方式是用SpringMvc去访问的后台。当然你也直接可以用servlet

@Controller
@RequestMapping("/base2")
public class codechange {
    @RequestMapping("/validate")
    private void validate(HttpServletRequest request, HttpServletResponse response) throws Exception{
        System.out.println("*********************验证码查询进来了*********************************");
        BufferedImage bfi = new BufferedImage(75, 35, BufferedImage.TYPE_INT_RGB);
        Graphics g = bfi.getGraphics();
        g.fillRect(0, 0, 75, 35);
        //验证码字符范围
        char[] ch = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789".toCharArray();
        Random r = new Random();
        int index;
        StringBuffer sb = new StringBuffer(); //保存字符串
        for (int i = 0; i < 4; i++) {
            index = r.nextInt(ch.length);
            g.setColor(new Color(r.nextInt(255), r.nextInt(255), r.nextInt(255)));
            Font font = new Font("宋体", 30, 30);
            g.setFont(font);
            g.drawString(ch[index] + "", (i * 20) + 2, 23);
            sb.append(ch[index]);
        }
        // 添加噪点
       /* int area = (int) (0.02 * 80 * 25);
        for (int i = 0; i < area; ++i) {
            int x = (int) (Math.random() * 80);
            int y = (int) (Math.random() * 25);
            bfi.setRGB(x, y, (int) (Math.random() * 255));
        }*/
        //设置验证码中的干扰线
        for (int i = 0; i < 6; i++) {
            //随机获取干扰线的起点和终点
            int xstart = (int) (Math.random() * 80);
            int ystart = (int) (Math.random() * 25);
            int xend = (int) (Math.random() * 80);
            int yend = (int) (Math.random() * 25);
            g.drawLine(xstart, ystart, xend, yend);
        }
        HttpSession session = request.getSession();  //保存到session
        session.setAttribute("verificationCode", sb.toString());
        ImageIO.write(bfi, "JPG", response.getOutputStream());  //写到输出流
        System.out.println("验证码制作完毕："+sb.toString());
    }
    @RequestMapping("/check")
    @ResponseBody
    private Map check(HttpServletRequest request, HttpServletResponse response) throws Exception{
        System.out.println("*******************验证码校验开始***************");
        HttpSession session =request.getSession();
        String verificationCode = (String)session.getAttribute("verificationCode");
        System.out.println("**sesion中的验证码为****************"+verificationCode);
        String checkcode = request.getParameter("texts");
        System.out.println("**前端传来中的验证码为****************"+checkcode);
        Map map=new HashMap();
        if(checkcode.equalsIgnoreCase(verificationCode)){
            System.out.println("*******************验证码校验结束，相等****************");
            map.put("boo",new String("true"));
            System.out.println("map的值"+map.get("boo"));
        }else{
            System.out.println("*******************验证码校验结束，不相等****************");
            map.put("boo",new String("false"));
        }
         return map;
    }
}