在注册、登录的页面上经常会出现验证码，为了防止频繁的注册或登录行为。下面是我用java制作的一个验证码，供初学者参考，做完验证码之后，我们可以用ajax进行验证码验证。
功能一：验证码制作的代码，点击图片，验证码进行更换
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/** * 显示验证码图片 */public void showCheckCode(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { // 调用业务逻辑 String checkCode = getCheckCode(); //将验证码字符放入session域对象中 req.getSession().setAttribute("checkCode", checkCode); //图片宽 int width = 80; //图片高 int height = 30; //在内存中创建一个图片 BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB); //获取一个画笔 Graphics g = image.getGraphics(); //设置画笔颜色，用灰色做背景 g.setColor(Color.GRAY); //向Image中填充灰色 g.fillRect(0,0,width,height); Random r = new Random(); //设置3条干扰线 for (int i = 0; i < 3; i++) { g.setColor(new Color(r.nextInt(255),r.nextInt(255),r.nextInt(255))); g.drawLine(r.nextInt(80), r.nextInt(30), r.nextInt(80), r.nextInt(80)); } //设置验证码字符串的颜色 g.setColor(new Color(r.nextInt(255),r.nextInt(255),r.nextInt(255))); //设置字符的大小 g.setFont(new Font("黑体",Font.BOLD,24)); //在图片中写入验证码字符串 g.drawString(checkCode,15,20); //将Image对象以PNG格式输出给所有的客户端 ImageIO.write(image,"PNG",resp.getOutputStream());}/** * 获取4位验证码中的4位随机字符串 */public static String getCheckCode(){ //验证码中的字符由数字和大小写字母组成 String code = "0123456789qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM"; Random r = new Random(); StringBuffer sb = new StringBuffer(); for (int i = 0; i < 4; i++) { sb.append(code.charAt(r.nextInt(code.length()))); } return sb.toString();} |
jsp页面
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<script type="text/javascript"> function changeCodeImage(img){ img.src = "${pageContext.request.contextPath}/UserServlet?method=showCheckCode&time="+new Date().getTime(); }</script> <div class="form-group"> <label for="date" class="col-sm-2 control-label">验证码</label> <div class="col-sm-3"> <input type="text" class="form-control" id="writeCode" onkeyup="checkCodeMethod(this.value)" > </div> <div class="col-sm-2"> <img src="${pageContext.request.contextPath}/UserServlet?method=showCheckCode" id="checkCodeImage" title="点击换一张" onclick="changeCodeImage(this)" /> </div> <span id="checkCodeSpan"></span> </div> |
功能二：ajax动态验证验证码
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/** * 验证验证码 */public void checkCode(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { //获取从页面中接收到的验证码参数 String checkCode = req.getParameter("checkCode"); //从session域对象中获取验证码 String sessionCode = (String) req.getSession().getAttribute("checkCode"); //判断验证码是否相同 if (checkCode.equalsIgnoreCase(sessionCode)) { resp.getWriter().print(true); }else { resp.getWriter().print(false); } |
jsp页面
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<script type="text/javascript"> function changeCodeImage(img){ img.src = "${pageContext.request.contextPath}/UserServlet?method=showCheckCode&time="+new Date().getTime(); } function checkCodeMethod(code){ $.get("${pageContext.request.contextPath}/UserServlet?method=checkCode", { checkCode: code}, function(data){ if (data == 'true') { document.getElementById("checkCodeSpan").innerHTML = "<font>验证码正确!</font>"; }else { document.getElementById("checkCodeSpan").innerHTML = "<font>验证码错误!</font>"; } } ); }</script> <div class="form-group"> <label for="date" class="col-sm-2 control-label">验证码</label> <div class="col-sm-3"> <input type="text" class="form-control" id="writeCode" onkeyup="checkCodeMethod(this.value)" > </div> <div class="col-sm-2"> <img src="${pageContext.request.contextPath}/UserServlet?method=showCheckCode" id="checkCodeImage" title="点击换一张" onclick="changeCodeImage(this)" /> </div> <span id="checkCodeSpan"></span> </div> |
感谢阅读，希望能帮助到大家，谢谢大家对本站的支持！
原文链接：http://blog.csdn.net/shuaicihai/article/details/54730590
