一个用jsp+Servlet+jquery+ajax实现的验证码，及验证是否正确。供初学者学习交流。
效果图：
源代码：
validate.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme() + "://"
+ request.getServerName() + ":" + request.getServerPort()
+ path + "/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>验证码</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<style type="text/css">
.error{
background: url(./p_w_picpaths/invalid_line.gif) repeat-x bottom;
border: 1px solid red;
}
</style>
<script type="text/javascript" src="./js/jquery.js"></script>
<script type="text/javascript">
$(function(){
$("#check").blur(function(){
$.ajax({
type:'post',
url:'check',
data: {input: $(this).val()},
dataType: "text/json",
success: function(msg){
var ret = eval（'(' + msg + ')');
var success = ret.success;
$("#tip").html(ret.message);
if(!success){
$(this).val('');
$("#p_w_picpath").attr('src',"validate?random="+Math.random());
$("#check").addClass("error");
$("#tip").css({'color':'red','font-family': '华文楷体'});
}else{
$("#check").removeClass("error");
$("#tip").css({'color':'black','font-family': '华文楷体'});
}
}
});
});
$("#p_w_picpath").click(function(){
$(this).attr('src',"validate?random="+Math.random());
});
});
</script>
</head>
<body>
<input type="text" id="check" value="">
<div id="tip"> </div>
<br>
<img alt="" src="validate" id="p_w_picpath">
</body>
</html>web.xml
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="2.5" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"> <servlet-mapping> <servlet-name>validate</servlet-name> <url-pattern>/validate</url-pattern> </servlet-mapping> <servlet> <servlet-name>validate</servlet-name> <servlet-class>test.MyValidateServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>check</servlet-name> <url-pattern>/check</url-pattern> </servlet-mapping> <servlet> <servlet-name>check</servlet-name> <servlet-class>test.CheckServlet</servlet-class> </servlet> </web-app>
ValidateCode.java
package util;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.p_w_picpath.BufferedImage;
import java.util.Random;
public class ValidateCode {
public static final int TYPE_NUM_ONLY = 0;
public static final int TYPE_LETTER_ONLY = 1;
public static final int TYPE_ALL_MIXED = 2;
public static final int TYPE_NUM_UPPER = 3;
public static final int TYPE_NUM_LOWER = 4;
public static final int TYPE_UPPER_ONLY = 5;
public static final int TYPE_LOWER_ONLY = 6;
public static String generateTextCode(int type, int length, String exChars) {
if (length <= 0) {
return "";
}
StringBuffer code = new StringBuffer();
int i = 0;
Random r = new Random();
switch (type) {
case 0:
while (i < length) {
int t = r.nextInt(10);
if ((exChars == null) || (exChars.indexOf(t) < 0)) {
code.append(t);
i++;
}
}
break;
case 1:
while (i < length) {
int t = r.nextInt(123);
if (((t >= 97) || ((t >= 65) && (t <= 90)))
&& ((exChars == null) || (exChars.indexOf((char) t) < 0))) {
code.append((char) t);
i++;
}
}
break;
case 2:
while (i < length) {
int t = r.nextInt(123);
if (((t < 97) && ((t < 65) || (t > 90)) && ((t < 48) || (t > 57)))
|| ((exChars != null) && (exChars.indexOf((char) t) >= 0)))
continue;
code.append((char) t);
i++;
}
break;
case 3:
while (i < length) {
int t = r.nextInt(91);
if (((t >= 65) || ((t >= 48) && (t <= 57)))
&& ((exChars == null) || (exChars.indexOf((char) t) < 0))) {
code.append((char) t);
i++;
}
}
break;
case 4:
while (i < length) {
int t = r.nextInt(123);
if (((t >= 97) || ((t >= 48) && (t <= 57)))
&& ((exChars == null) || (exChars.indexOf((char) t) < 0))) {
code.append((char) t);
i++;
}
}
break;
case 5:
while (i < length) {
int t = r.nextInt(91);
if ((t >= 65)
&& ((exChars == null) || (exChars.indexOf((char) t) < 0))) {
code.append((char) t);
i++;
}
}
break;
case 6:
while (i < length) {
int t = r.nextInt(123);
if ((t >= 97)
&& ((exChars == null) || (exChars.indexOf((char) t) < 0))) {
code.append((char) t);
i++;
}
}
}
return code.toString();
}
public static BufferedImage generateImageCode(String textCode, int width,
int height, int interLine, boolean randomLocation, Color backColor,
Color foreColor, Color lineColor) {
BufferedImage bim = new BufferedImage(width, height, 1);
Graphics g = bim.getGraphics();
g.setColor(backColor == null ? getRandomColor() : backColor);
g.fillRect(0, 0, width, height);
Random r = new Random();
if (interLine > 0) {
int x = 0;
int y = 0;
int x1 = width;
int y1 = 0;
for (int i = 0; i < interLine; i++) {
g.setColor(lineColor == null ? getRandomColor() : lineColor);
y = r.nextInt(height);
y1 = r.nextInt(height);
g.drawLine(x, y, x1, y1);
}
}
int fsize = (int) (height * 0.8D);
int fx = height - fsize;
int fy = fsize;
g.setFont(new Font("Default", 0, fsize));
for (int i = 0; i < textCode.length(); i++) {
fy = randomLocation ? (int) ((Math.random() * 0.3D + 0.6D) * height)
: fy;
g.setColor(foreColor == null ? getRandomColor() : foreColor);
g.drawString(String.valueOf(textCode.charAt(i)), fx, fy);
fx = (int) (fx + fsize * 0.9D);
}
g.dispose();
return bim;
}
public static BufferedImage generateImageCode(int type, int length,
String exChars, int width, int height, int interLine,
boolean randomLocation, Color backColor, Color foreColor,
Color lineColor) {
String textCode = generateTextCode(type, length, exChars);
BufferedImage bim = generateImageCode(textCode, width, height,
interLine, randomLocation, backColor, foreColor, lineColor);
return bim;
}
private static Color getRandomColor() {
Random r = new Random();
Color c = new Color(r.nextInt(255), r.nextInt(255), r.nextInt(255));
return c;
}
}MyValidateServlet.java
package test;
import java.awt.Color;
import java.awt.p_w_picpath.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
import javax.p_w_picpathio.ImageIO;
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 util.ValidateCode;
public class MyValidateServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
resp.setHeader("Pragma", "No-cache");// 设置响应头信息，告诉浏览器不要缓存此内容
resp.setHeader("Cache-Control", "no-cache");
resp.setDateHeader("Expire", 0);
try {
String textCode = ValidateCode.generateTextCode(
ValidateCode.TYPE_ALL_MIXED, 6, null);
BufferedImage p_w_picpath = ValidateCode.generateImageCode(textCode, 500,
100, 5, true, Color.GRAY, null, null);
HttpSession session = req.getSession(true);
session.setAttribute("captcha", textCode);
resp.setContentType("p_w_picpath/jpeg");
OutputStream outputStream = resp.getOutputStream();
ImageIO.write(p_w_picpath, "jpeg", outputStream);
} catch (Exception e) {
e.printStackTrace();
}
}
}CheckServlet.java
package test;
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;
import javax.servlet.http.HttpSession;
public class CheckServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
resp.setCharacterEncoding("UTF-8");
resp.setContentType("text/html;chartset=UTF-8");
req.setCharacterEncoding("UTF-8");
String input = (String) req.getParameter("input");
HttpSession sess = req.getSession();
String captcha = (String) sess.getAttribute("captcha");
PrintWriter out = resp.getWriter();
if(input.toUpperCase().equals(captcha.toUpperCase())){
out.print("{'success': true,'message': '验证码正确！'}");
}else{
out.print("{'success': false,'message': '验证码错误！'}");
}
out.flush();
out.close();
}
}
