ajax+servlet实现无刷新验证码实例

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1.index.jsp

<%@ page isELIgnored="false" language="java" import="java.util.*"pageEncoding="utf-8"%><%String path = request.getContextPath();%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head><title>ajax实现无刷新验证码实例</title></head><mce:script language="javascript"></mce:script><body><input type="hidden" value="<%=path%>" id="path" /><form action="#" method="post"onsubmit="return validata();"><div id="info" style="display: none; color: red;font-size: 12px;" mce_style="display: none; color: red;font-size: 12px;"></div>验证码：<input id="code" type="text" name="num" size="10" maxlength="4" onblur="judgeCode()"><img id="imgCode" style="border: 1px solid #C6D8E5; cursor: pointer;" mce_style="border: 1px solid #C6D8E5; cursor: pointer;"src="<%=path%>/servlet/textBufferedImage?timestampt="+<%=new java.util.Date().getTime()%> title="点击重新申请"onclick="refresh();" /><a href="javascript:refresh();" mce_href="javascript:refresh();">看不清?换一张</a><br><input type="submit" value="提交 "><br></form></body></html>

2.judgeCode.java(判断验证码是否正确)

package servlet;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 judgeCode extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setContentType("text/html");response.setCharacterEncoding("utf-8");String code=request.getParameter("code");String result="false";String randomCode=(String)request.getSession().getAttribute("randomCode");if(code.equalsIgnoreCase(randomCode)){result="true";}response.getWriter().write(result);response.getWriter().flush();}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doGet(request,response);}}

3.TextBufferedImage.java(生成验证码图片)

package servlet;import java.awt.Color;import java.awt.Font;import java.awt.Graphics2D;import java.awt.image.BufferedImage;import java.io.IOException;import java.io.OutputStream;import java.util.Random;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;import com.sun.image.codec.jpeg.JPEGCodec;import com.sun.image.codec.jpeg.JPEGImageEncoder;public class TextBufferedImage extends HttpServlet{ public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException { //产生随机密码 resp.setHeader("Cache-Control","no-cache"); HttpSession session = req.getSession(); String randomPassword = getRandom(4); System.out.println("randomPassword="+randomPassword); session.setAttribute("randomCode", randomPassword); OutputStream out = resp.getOutputStream(); try { JPEGImageEncoder encode = JPEGCodec.createJPEGEncoder(out); BufferedImage bi = CreateBufferedImage(randomPassword); encode.encode(bi); } catch (Exception e) { e.printStackTrace(); } } /** * 把随机码写到图片上返回 * * @param randomPassword //随机码 * @return */ private BufferedImage CreateBufferedImage(String randomPassword) { int width = 80; int height = 40; BufferedImage bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); Graphics2D g2d = bufferedImage.createGraphics(); g2d.clearRect(0, 0, width, height); // 设定背景色 g2d.setColor(getRandColor(200,250)); g2d.fillRect(0, 0, width, height); // 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到 Random random = new Random(); g2d.setColor(getRandColor(160,200)); g2d.setFont(getFont()); for (int i=0;i<155;i++) { int x = random.nextInt(width); int y = random.nextInt(height); int xl = random.nextInt(12); int yl = random.nextInt(12); g2d.drawLine(x,y,x+xl,y+yl); } // 取随机产生的认证码(4位数字) String sRand=""; for (int i=0;i<4;i++){ String rand = randomPassword.substring(i, i+1); sRand+=rand; // 将认证码显示到图象中 g2d.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));//调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成 g2d.drawString(rand,14*i+12,30); } g2d.dispose(); return bufferedImage; } private Color getRandColor(int fc, int bc) {// 给定范围获得随机颜色Random random = new Random();if (fc > 255)fc = 255;if (bc > 255)bc = 255;int r = fc + random.nextInt(bc - fc);int g = fc + random.nextInt(bc - fc);int b = fc + random.nextInt(bc - fc);return new Color(r, g, b);} private Font getFont() {Random random = new Random();Font font[] = new Font[5];font[0] = new Font("Ravie", Font.PLAIN, 25);font[1] = new Font("Antique Olive Compact", Font.PLAIN, 25);font[2] = new Font("Forte", Font.PLAIN, 25);font[3] = new Font("Wide Latin", Font.PLAIN, 25);font[4] = new Font("Gill Sans Ultra Bold", Font.PLAIN, 23);return font[random.nextInt(5)];} /** * 产生随机码(字母+数字) * * @param length * 随机码长度 * @return 随机码 */private String getRandom(int length) {String randomCode = "";for (int i = 0; i < length; i++) {randomCode += getRandChar();}return randomCode;}public String getRandChar() {int rand = (int) Math.round(Math.random() * 2);long itmp = 0;char ctmp = '/u0000';// 根据rand的值来决定来生成一个大写字母、小写字母和数字switch (rand) {// 生成大写字母case 1:itmp = Math.round(Math.random() * 25 + 65);ctmp = (char) itmp;return String.valueOf(ctmp);// 生成小写字母case 2:itmp = Math.round(Math.random() * 25 + 97);ctmp = (char) itmp;return String.valueOf(ctmp);// 生成数字default:itmp = Math.round(Math.random() * 9);return String.valueOf(itmp);}}}

4.配置web.xml

<?xml version="1.0" encoding="UTF-8"?><web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"> <servlet> <description>This is the description of my J2EE component</description> <display-name>This is the display name of my J2EE component</display-name> <servlet-name>TextBufferedImage</servlet-name> <servlet-class>servlet.TextBufferedImage</servlet-class> </servlet> <servlet> <description>This is the description of my J2EE component</description> <display-name>This is the display name of my J2EE component</display-name> <servlet-name>judgeCode</servlet-name> <servlet-class>servlet.judgeCode</servlet-class> </servlet> <servlet-mapping> <servlet-name>TextBufferedImage</servlet-name> <url-pattern>/servlet/textBufferedImage</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>judgeCode</servlet-name> <url-pattern>/servlet/judgeCode</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>/jsp/index.jsp</welcome-file> </welcome-file-list></web-app>

5.运行效果

另附一个验证码生成servlet：

package sunyang.vote.util;import java.awt.Color;import java.awt.Font;import java.awt.Graphics;import java.awt.image.BufferedImage;import java.io.IOException;import java.util.Random;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;import com.sun.image.codec.jpeg.JPEGCodec;import com.sun.image.codec.jpeg.JPEGImageEncoder;@SuppressWarnings("serial")public class SafeCode extends HttpServlet {public SafeCode() {}public void init() throws ServletException {super.init();}public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setContentType("image/jpeg");response.setHeader("Cache-Control", "no-cache");response.setHeader("Pragma", "No-cache");response.setDateHeader("Expires", 0L);HttpSession session = request.getSession();int width = 60;int height = 20;BufferedImage image = new BufferedImage(width, height, 1);Graphics g = image.getGraphics();Random random = new Random();g.setColor(getRandColor(200, 250));g.fillRect(0, 0, width, height);g.setFont(new Font("Arial", 0, 19));g.setColor(getRandColor(160, 200));for (int i = 0; i < 155; i++) {int x = random.nextInt(width + 100);int y = random.nextInt(height + 100);int xl = random.nextInt(10);int yl = random.nextInt(12);g.drawOval(x, y, x + xl, y + yl);}String sRand = "";for (int i = 0; i < 4; i++) {String rand = getRandChar(random.nextInt(36));sRand = sRand + rand;g.setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random.nextInt(110)));g.drawString(rand, 13 * i + 6, 16);}session.setAttribute("rand", sRand);g.dispose();javax.servlet.ServletOutputStream imageOut = response.getOutputStream();JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(imageOut);encoder.encode(image);}public void destroy() {}private Color getRandColor(int fc, int bc) {Random random = new Random();if (fc > 255)fc = 255;if (bc > 255)bc = 255;int r = fc + random.nextInt(bc - fc);int g = fc + random.nextInt(bc - fc);int b = fc + random.nextInt(bc - fc);return new Color(r, g, b);}private String getRandChar(int randNumber) {return CHARARRAY[randNumber];}//private static final String CONTENT_TYPE = "image/jpeg";private static final String CHARARRAY[] = { "0", "1", "2", "3", "4", "5","6", "7", "8", "9", "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" };}