java制作验证码并进行验证

来源：互联网发布：sql server培训费用编辑：程序博客网时间：2024/06/03 09:07

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

/** * 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

<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

/** * 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

<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>

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