验证码配置方法
1.在web.xml下配置2个servlet，VerifyCodeServlet用来生成验证码图像，ResultServlet用来做服务器端验证。
<servlet><servlet-name>VerifyCodeServlet</servlet-name><servlet-class>VerifyCodeServlet</servlet-class></servlet><servlet><servlet-name>ResultServlet</servlet-name><servlet-class>ResultServlet</servlet-class></servlet> <servlet-mapping><servlet-name>VerifyCodeServlet</servlet-name><url-pattern>/verifyCodeServlet</url-pattern></servlet-mapping><servlet-mapping><servlet-name>ResultServlet</servlet-name><url-pattern>/resultServlet</url-pattern></servlet-mapping>
2.servlet类文件
import java.awt.Color; import java.awt.Font; import java.awt.Graphics2D; import java.awt.image.BufferedImage; import java.util.Random; import javax.imageio.ImageIO; import javax.servlet.ServletException; import javax.servlet.ServletOutputStream; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; public class VerifyCodeServlet extends HttpServlet { /** * 验证码图片的宽度。 */ private int width = 70; /** *验证码图片的高度。 */ private int height = 20; /** * 验证码字符个数 */ private int codeCount = 4; /** * xx */ private int xx = 0; /** * 字体高度 */ private int fontHeight; /** * codeY */ private int codeY; /** * codeSequence */ char[] codeSequence = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' }; /** * 初始化验证图片属性 */ public void init() throws ServletException { // 从web.xml中获取初始信息 // 宽度 String strWidth = this.getInitParameter("width"); // 高度 String strHeight = this.getInitParameter("height"); // 字符个数 String strCodeCount = this.getInitParameter("codeCount"); // 将配置的信息转换成数值 try { if (strWidth != null && strWidth.length() != 0) { width = Integer.parseInt(strWidth); } if (strHeight != null && strHeight.length() != 0) { height = Integer.parseInt(strHeight); } if (strCodeCount != null && strCodeCount.length() != 0) { codeCount = Integer.parseInt(strCodeCount); } } catch (NumberFormatException e) { e.printStackTrace(); } xx = width / (codeCount + 1); fontHeight = height - 2; codeY = height - 4; } /** * @param req * @param resp * @throws ServletException * @throws java.io.IOException */ protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, java.io.IOException { // 定义图像buffer BufferedImage buffImg = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); Graphics2D gd = buffImg.createGraphics(); // 创建一个随机数生成器类 Random random = new Random(); // 将图像填充为白色 gd.setColor(Color.WHITE); gd.fillRect(0, 0, width, height); // 创建字体，字体的大小应该根据图片的高度来定。 Font font = new Font("Fixedsys", Font.PLAIN, fontHeight); // 设置字体。 gd.setFont(font); // 画边框。 gd.setColor(Color.BLACK); gd.drawRect(0, 0, width - 1, height - 1); // 随机产生160条干扰线，使图象中的认证码不易被其它程序探测到。 gd.setColor(Color.lightGray); for (int i = 0; i < 16; i++) { int x = random.nextInt(width); int y = random.nextInt(height); int xl = random.nextInt(12); int yl = random.nextInt(12); gd.drawLine(x, y, x + xl, y + yl); } // randomCode用于保存随机产生的验证码，以便用户登录后进行验证。 StringBuffer randomCode = new StringBuffer(); int red = 0, green = 0, blue = 0; // 随机产生codeCount数字的验证码。 for (int i = 0; i < codeCount; i++) { // 得到随机产生的验证码数字。 String strRand = String.valueOf(codeSequence); // 产生随机的颜色分量来构造颜色值，这样输出的每位数字的颜色值都将不同。 red = random.nextInt(255); green = random.nextInt(255); blue = random.nextInt(255); // 用随机产生的颜色将验证码绘制到图像中。 gd.setColor(new Color(red, green, blue)); gd.drawString(strRand, (i + 1) * xx, codeY); // 将产生的四个随机数组合在一起。 randomCode.append(strRand); } // 将四位数字的验证码保存到Session中。 HttpSession session = req.getSession(); session.setAttribute("validateCode", randomCode.toString()); // 禁止图像缓存。 resp.setHeader("Pragma", "no-cache"); resp.setHeader("Cache-Control", "no-cache"); resp.setDateHeader("Expires", 0); resp.setContentType("image/jpeg"); // 将图像输出到Servlet输出流中。 ServletOutputStream sos = resp.getOutputStream(); ImageIO.write(buffImg, "jpeg", sos); sos.close(); } }
import java.io.IOException; import java.io.PrintWriter; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class ResultServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doPost(request, response); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html;charset=utf-8"); String validateC = (String) request.getSession().getAttribute("validateCode"); String veryCode = request.getParameter("code"); PrintWriter out = response.getWriter(); veryCode = veryCode.toUpperCase(); if(veryCode==null||"".equals(veryCode)){ out.print("false"); }else{ if(validateC.equals(veryCode)){ out.print("true"); }else{ out.print("false"); } } out.flush(); out.close(); } }
3.jsp页面显示
<input type="text" id="checkCode" name="checkCode" class="s_td"/><img id="imgObj" alt="" src="<c:url value='/verifyCodeServlet'/>" style="vertical-align:top;margin-top:1px;margin-left:5px;"/>&nbsp;&nbsp; <a href="javascript:void(0);" >看不清,换一张</a> <span id="error"></span>
4.ajax验证
//------改变验证码内容------function changeImg(){ var imgSrc = $("#imgObj"); imgSrc.attr("src",chgUrl("<c:url value='/verifyCodeServlet'/>")); $("#checkCode").focus();}//时间戳 //为了使每次生成图片不一致，即不让浏览器读缓存，所以需要加上时间戳 function chgUrl(url){ var timestamp = (new Date()).valueOf(); if((url.indexOf("&")>=0)){ url = url + "&tamp=" + timestamp; }else{ url = url + "?timestamp=" + timestamp; } return url; }//判断输入的验证码是否正确function isRightCode(){ var res = "false"; var code = $("#checkCode").attr("value"); code = "data="+new Date()+"&code=" + code; $.ajax({ type:"POST", url:"<c:url value='/resultServlet'/>", data:code, //同步 async:false, success:function(data){ res=data; } }); return res;}
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