<%@ page contentType="image/jpeg" import="java.awt.*,
java.awt.image.*,java.util.*,javax.imageio.*" %>
<%
// 在内存中创建图象
int width=60, height=20;
BufferedImage image = new BufferedImage(width, height,
BufferedImage.TYPE_INT_RGB);
// 获取图形上下文
Graphics g = image.getGraphics();
// 设定背景色
g.setColor(new Color(0xDCDCDC));
g.fillRect(0, 0, width, height);
//画边框
g.setColor(Color.black);
g.drawRect(0,0,width-1,height-1);
// 取随机产生的认证码(4位数字)
String rand = request.getParameter("rand");
rand = rand.substring(0,rand.indexOf("."));
switch(rand.length())
{
case 1: rand = "000"+rand; break;
case 2: rand = "00"+rand; break;
case 3: rand = "0"+rand; break;
default: rand = rand.substring(0,4); break;
}
// 将认证码存入SESSION
session.setAttribute("rand",rand);
// 将认证码显示到图象中
g.setColor(Color.black);
Integer tempNumber = new Integer(rand);
String numberStr = tempNumber.toString();
g.setFont(new Font("Atlantic Inline",Font.PLAIN,18));
String Str = numberStr.substring(0,1);
g.drawString(Str,8,17);
Str = numberStr.substring(1,2);
g.drawString(Str,20,15);
Str = numberStr.substring(2,3);
g.drawString(Str,35,18);
Str = numberStr.substring(3,4);
g.drawString(Str,45,15);
// 随机产生88个干扰点，使图象中的认证码不易被其它程序探测到
Random random = new Random();
for (int i=0;i<20;i++)
{
int x = random.nextInt(width);
int y = random.nextInt(height);
g.drawOval(x,y,0,0);
}
// 图象生效
g.dispose();
// 输出图象到页面
ImageIO.write(image, "JPEG", response.getOutputStream());
%>
生成有4个随机数字和杂乱背景的图片，数字和背景颜色会改变，服务器端刷新（用history.go(-1)也会变）
产生验证码图片的文件image.jsp
<%@ page contentType="image/jpeg" import="java.awt.*,
java.awt.image.*,java.util.*,javax.imageio.*" %>
<%!
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);
}
%>
<%
//设置页面不缓存
response.setHeader("Pragma","No-cache");
response.setHeader("Cache-Control","no-cache");
response.setDateHeader("Expires", 0);
// 在内存中创建图象
int width=60, height=20;
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
// 获取图形上下文
Graphics g = image.getGraphics();
//生成随机类
Random random = new Random();
// 设定背景色
g.setColor(getRandColor(200,250));
g.fillRect(0, 0, width, height);
//设定字体
g.setFont(new Font("Times New Roman",Font.PLAIN,18));
//画边框
//g.setColor(new Color());
//g.drawRect(0,0,width-1,height-1);
// 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
g.setColor(getRandColor(160,200));
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);
g.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=String.Of(random.nextInt(10));
sRand+=rand;
// 将认证码显示到图象中
g.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
g.drawString(rand,13*i+6,16);
}
// 将认证码存入SESSION
session.setAttribute("rand",sRand);
// 图象生效
g.dispose();
// 输出图象到页面
ImageIO.write(image, "JPEG", response.getOutputStream());
%>
使用验证码图片的文件a.jsp
<%@ page contentType="text/html;charset=gb2312" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>认证码输入页面</title>
< http-equiv="Content-Type" content="text/html; charset=gb2312">
< HTTP-EQUIV="Pragma" CONTENT="no-cache">
< HTTP-EQUIV="Cache-Control" CONTENT="no-cache">
< HTTP-EQUIV="Expires" CONTENT="0">
</head>
<body>
<form method=post action="check.jsp">
<table>
<tr>
<td align=left>系统产生的认证码：</td>
<td><img border=0 src="/image.jsp"></td>
</tr>
<tr>
<td align=left>输入上面的认证码：</td>
<td><input type=text name=rand maxlength=4 =""></td>
</tr>
<tr>
<td colspan=2 align=center><input type=submit ="提交检测"></td>
</tr>
</form>
</body>
</html>
验证的页面check.jsp
<%@ page contentType="text/html; charset=gb2312" language="java" import="java.sql.*" errorPage="" %>
<html>
<head>
<title>认证码验证页面</title>
< http-equiv="Content-Type" content="text/html; charset=gb2312">
< HTTP-EQUIV="Pragma" CONTENT="no-cache">
< HTTP-EQUIV="Cache-Control" CONTENT="no-cache">
< HTTP-EQUIV="Expires" CONTENT="0">
</head>
<body>
<%
String rand = (String)session.getAttribute("rand");
String input = request.getParameter("rand");
%>
系统产生的认证码为： <%= rand %><br>
您输入的认证码为： <%= input %><br>
<br>
<%
if (rand.equals(input)) {
%>
<font color=green>输入相同，认证成功！</font>
<%
} else {
%>
<font color=red>输入不同，认证失败！</font>
<%
}
%>
</body>
</html>
<%@ page contentType="image/jpeg" import="java.awt.*,
java.awt.image.*,java.util.*,javax.imageio.*" %>
<%
// 在内存中创建图象
int width=60, height=20;
BufferedImage image = new BufferedImage(width, height,
BufferedImage.TYPE_INT_RGB);
// 获取图形上下文
Graphics g = image.getGraphics();
// 设定背景色
g.setColor(new Color(0xDCDCDC));
g.fillRect(0, 0, width, height);
//画边框
g.setColor(Color.black);
g.drawRect(0,0,width-1,height-1);
// 取随机产生的认证码(4位数字)
String rand = request.getParameter("rand");
rand = rand.substring(0,rand.indexOf("."));
switch(rand.length())
{
case 1: rand = "000"+rand; break;
case 2: rand = "00"+rand; break;
case 3: rand = "0"+rand; break;
default: rand = rand.substring(0,4); break;
}
// 将认证码存入SESSION
session.setAttribute("rand",rand);
// 将认证码显示到图象中
g.setColor(Color.black);
Integer tempNumber = new Integer(rand);
String numberStr = tempNumber.toString();
g.setFont(new Font("Atlantic Inline",Font.PLAIN,18));
String Str = numberStr.substring(0,1);
g.drawString(Str,8,17);
Str = numberStr.substring(1,2);
g.drawString(Str,20,15);
Str = numberStr.substring(2,3);
g.drawString(Str,35,18);
Str = numberStr.substring(3,4);
g.drawString(Str,45,15);
// 随机产生88个干扰点，使图象中的认证码不易被其它程序探测到
Random random = new Random();
for (int i=0;i<20;i++)
{
int x = random.nextInt(width);
int y = random.nextInt(height);
g.drawOval(x,y,0,0);
}
// 图象生效
g.dispose();
// 输出图象到页面
ImageIO.write(image, "JPEG", response.getOutputStream());
%>
另外一种:
生成验证码文件：
<%@ page contentType="image/jpeg" import="java.awt.*,
java.awt.image.*,java.util.*,javax.imageio.*" %>
<%!
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);
}
%>
<%
out.clear();//这句针对resin服务器，如果是tomacat可以不要这句
response.setHeader("Pragma","No-cache");
response.setHeader("Cache-Control","no-cache");
response.setDateHeader("Expires", 0);
int width=60, height=20;
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
Graphics g = image.getGraphics();
Random random = new Random();
g.setColor(getRandColor(200,250));
g.fillRect(0, 0, width, height);
g.setFont(new Font("Times New Roman",Font.PLAIN,18));
g.setColor(getRandColor(160,200));
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);
g.drawLine(x,y,x+xl,y+yl);
}
String sRand="";
for (int i=0;i<4;i++){
String rand=String.Of(random.nextInt(10));
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);
}
// 将认证码存入SESSION
session.setAttribute("rand",sRand);
g.dispose();
ImageIO.write(image, "JPEG", response.getOutputStream());
%>
验证：
<%
//读取提交的表单内容
String rand=(String)session.getAttribute("rand");
String input=request.getParameter("rand");
if (rand.equals(input))
{
response.sendRedirect("success.jsp");
}
else
{
.....
}
%>
html代码自己写
servlet验证码程序
/*
*生产随机显示的验证码图片
*
*/
package webutil;
import java.io.*;
import javax.servlet.http.*;
import javax.servlet.*;
import java.util.*;
import java.util.Random;
import java.awt.*;
import java.awt.image.*;
import javax.imageio.*;
//import com.sun.image.codec.jpeg.*;
public class VImage extends HttpServlet
{
public void init(ServletConfig conf) throws ServletException
{
super.init(conf);
}
public void doGet(HttpServletRequest req,HttpServletResponse res) throws ServletException, IOException
{
res.setContentType("image/jpeg");
res.setHeader("Pragma","No-cache");
res.setHeader("Cache-Control","no-cache");
res.setDateHeader("Expires", 0);
HttpSession session = req.getSession();
// 在内存中创建图象
int width=86, height=20;
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
// 获取图形上下文
Graphics g = image.getGraphics();
// 生成随机类
Random random = new Random();
// 设定背景色
g.setColor(getRandColor(200,250));
g.fillRect(0, 0, width, height);
// 设定字体
g.setFont(new Font("Times New Roman",Font.PLAIN,18));
// 画边框
//g.setColor(new Color());
//g.drawRect(0,0,width-1,height-1);
// 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
g.setColor(getRandColor(160,200));
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);
g.drawLine(x,y,x+xl,y+yl);
}
String rstr = "";
RandomStrg rst = new RandomStrg();
rst.setCharset("a-zA-Z0-9");
rst.setLength("6");
try {
rst.generateRandomObject();
rstr = rst.getRandom();
} catch (Exception ex) {
ex.printStackTrace();
}
// 取随机产生的认证码(4位数字)
String sRand="";
sRand = rstr;
for (int i=0;i<sRand.length();i++)
{
// String rand=String.Of(random.nextInt(10));
String rand = String.Of(rstr.charAt(i));
// sRand+=rand;
// 将认证码显示到图象中
g.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
g.drawString(rand,13*i+6,16);
}
// 将认证码存入SESSION
session.setAttribute("post_validate_code",sRand);
// 图象生效
g.dispose();
// 输出图象到页面
ImageIO.write(image, "JPEG", res.getOutputStream());
//JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(res.getOutputStream());
//encoder.encode(image);
}
public void doPost(HttpServletRequest req,HttpServletResponse res) throws ServletException, IOException
{
doGet(req,res);
}
//给定范围获得随机颜色
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);
}
}
//随机字符串bean
package mycollect;
import java.util.*;
import java.security.SecureRandom;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
public class RandomStrg {
private String randomstr;
private boolean allchars = false;
//欠缺是8位字符串
private Integer length = new Integer(8);
private HashMap hmap;
private ArrayList lower = null;
private ArrayList upper = null;
private char[] single = null;
private int singlecount = 0;
private boolean singles = false;
private String algorithm = null;
private String provider = null;
private boolean secure = false;
private Random random = null;
private SecureRandom secrandom = null;
private final float getFloat() {
if (random == null)
return secrandom.nextFloat();
else
return random.nextFloat();
}
/**
* generate the Random object that will be used for this random number
* generator
*
*/
public final void generateRandomObject() throws Exception {
// check to see if the object is a SecureRandom object
if (secure) {
try {
// get an instance of a SecureRandom object
if (provider != null)
// search for algorithm in package provider
random = SecureRandom.getInstance(algorithm, provider);
else
random = SecureRandom.getInstance(algorithm);
} catch (NoSuchAlgorithmException ne) {
throw new Exception(ne.getMessage());
} catch (NoSuchProviderException pe) {
throw new Exception(pe.getMessage());
}
} else
random = new Random();
}
/**
* generate the random string
*
*/
private final void generaterandom() {
if (allchars)
for (int i = 0; i < length.int(); i++)
randomstr = randomstr + new Character((char)((int) 34 +
((int)(getFloat() * 93)))).toString();
else if (singles) {
// check if there are single chars to be included
if (upper.size() == 3) {
// check for the number of ranges max 3 uppercase lowercase digits
// build the random string
for (int i = 0; i < length.int(); i++) {
// you have four groups to choose a random number from, to make
// the choice a little more random select a number out of 100
// get a random number even or odd
if (((int) (getFloat() * 100)) % 2 == 0) {
// the number was even get another number even or odd
if (((int) (getFloat() * 100)) % 2 == 0)
// choose a random char from the single char group
randomstr = randomstr + randomSingle().toString();
else
// get a random char from the first range
randomstr = randomstr + randomChar((Character)lower.get(2),
(Character)upper.get(2)).toString();
} else {
// the number was odd
if (((int) (getFloat() * 100)) % 2 == 0)
// choose a random char from the second range
randomstr = randomstr + randomChar((Character)lower.get(1),
(Character)upper.get(1)).toString();
else
// choose a random char from the third range
randomstr = randomstr + randomChar((Character)lower.get(0),
(Character)upper.get(0)).toString();
}
}
} else if (upper.size() == 2) {
// single chars are to be included choose a random char from
// two different ranges
// build the random char from single chars and two ranges
for (int i = 0; i < length.int(); i++) {
// select the single chars or a range to get each random char
// from
if (((int)(getFloat() * 100)) % 2 == 0) {
// get random char from the single chars
randomstr = randomstr + randomSingle().toString();
} else if (((int) (getFloat() * 100)) % 2 == 0) {
// get the random char from the first range
randomstr = randomstr + randomChar((Character)lower.get(1),
(Character)upper.get(1)).toString();
} else {
// get the random char from the second range
randomstr = randomstr + randomChar((Character)lower.get(0),
(Character)upper.get(0)).toString();
}
}
} else if (upper.size() == 1) {
// build the random string from single chars and one range
for (int i = 0; i < length.int(); i++) {
if (((int) getFloat() * 100) % 2 == 0)
// get a random single char
randomstr = randomstr + randomSingle().toString();
else
// get a random char from the range
randomstr = randomstr + randomChar((Character)lower.get(0),
(Character)upper.get(0)).toString();
}
} else {
// build the rand string from single chars
for (int i = 0; i < length.int(); i++)
randomstr = randomstr + randomSingle().toString();
}
} else {
// no single chars are to be included in the random string
if (upper.size() == 3) {
// build random strng from three ranges
for (int i = 0; i < length.int(); i++) {
if (((int) (getFloat() * 100)) % 2 == 0) {
// get random char from first range
randomstr = randomstr + randomChar((Character)lower.get(2),
(Character)upper.get(2)).toString();
} else if (((int) (getFloat() * 100)) % 2 == 0) {
// get random char form second range
randomstr = randomstr + randomChar((Character)lower.get(1),
(Character)upper.get(1)).toString();
} else {
// get random char from third range
randomstr = randomstr + randomChar((Character)lower.get(0),
(Character)upper.get(0)).toString();
}
}
} else if (upper.size() == 2) {
// build random string from two ranges
for (int i = 0; i < length.int(); i++) {
if (((int) (getFloat() * 100)) % 2 == 0)
// get random char from first range
randomstr = randomstr + randomChar((Character)lower.get(1),
(Character)upper.get(1)).toString();
else
// get random char from second range
randomstr = randomstr + randomChar((Character)lower.get(0),
(Character)upper.get(0)).toString();
}
} else
// build random string
for (int i = 0; i < length.int(); i++)
// get random char from only range
randomstr = randomstr + randomChar((Character)lower.get(0),
(Character)upper.get(0)).toString();
}
}
/**
* generate a random char from the single char list
*
* @returns - a randomly selscted character from the single char list
*
*/
private final Character randomSingle() {
return (new Character(single[(int)((getFloat() * singlecount) - 1)]));
}
/**
* generate a random character
*
* @param lower lower bound from which to get a random char
* @param upper upper bound from which to get a random char
*
* @returns - a randomly generated character
*
*/
private final Character randomChar(Character lower, Character upper) {
int tempval;
char low = lower.char();
char up = upper.char();
// get a random number in the range lowlow - lowup
tempval = (int)((int)low + (getFloat() * ((int)(up - low))));
// return the random char
return (new Character((char) tempval));
}
/**
* get the randomly created string for use with the
* <jsp:getProperty name=<i>"id"</i> property="randomstr"/>
*
* @return - randomly created string
*
*/
public final String getRandom() {
randomstr = new String();
generaterandom(); // generate the first random string
if (hmap != null) {
while (hmap.containsKey(randomstr)) {
// random string has already been created generate a different one
generaterandom();
}
hmap.put(randomstr, null); // add the new random string
}
return randomstr;
}
/**
* set the ranges from which to choose the characters for the random string
*
* @param low set of lower ranges
* @param up set of upper ranges
*
*/
public final void setRanges(ArrayList low, ArrayList up) {
lower = low;
upper = up;
}
/**
* set the hashmap that is used to check the uniqueness of random strings
*
* @param map hashmap whose keys are used to insure uniqueness of random strgs
*
*/
public final void setHmap(HashMap map) {
hmap = map;
}
/**
* set the length of the random string
*
* @param length of the random string
*
*/
public final void setLength(String ) {
length = new Integer();
}
/**
* set the algorithm name
*
* @param name of the algorithm to use for a SecureRandom object
*
*/
public final void setAlgorithm(String ) {
algorithm = ;
secure = true; // a SecureRandom object is to be used
}
/**
* set the provider name
*
* @param name of the package to check for the algorithm
*
*/
public final void setProvider(String ) {
provider = ;
}
/**
* set the allchars flag
*
* @param boolean of the allchars flag
*
*/
public final void setAllchars(boolean ) {
allchars = ;
}
/**
* set the array of single chars to choose from for this random string and the
* number of chars in the array
*
* @param chars the array of single chars
* @param the number of single chars
*
*/
public final void setSingle(char[] chars, int ) {
single = chars; // set the array of chars
singlecount = ; // set the number of chars in array single
singles = true; // set flag that single chars are in use
}
public final void setCharset(String )
{
// s tells the method whether or not to check for single chars
boolean more = true;
// create the arraylists to hold the upper and lower bounds for the char
// ranges
lower = new ArrayList(3);
upper = new ArrayList(3);
// user has chosen to use all possible characters in the random string
if (.compareTo("all") == 0) {
allchars = true; // set allchars flag
// all chars are to be used so there are no single chars to sort
// through
more = false;
}else if ((.charAt(1) == '-') && (.charAt(0) != '\\')) {
// run through the ranges at most 3
while (more && (.charAt(1) == '-')){
// check to make sure that the dash is not the single char
if (.charAt(0) == '\\')
break;
else {
// add upper and lower ranges to there list
lower.add(new Character(.charAt(0)));
upper.add(new Character(.charAt(2)));
}
// check to see if there is more to the charset
if (.length() <= 3)
more = false;
else
// create a new string so that the next range if there is one
// starts it
= .substring(3);
}
}
// if more = false there are no single chars in the charset
if (more) {
single = new char[30]; // create single
// create a set of tokens from the string of single chars
StringTokenizer tokens = new StringTokenizer();
while (tokens.hasMoreTokens()) {
// get the next token from the string
String token = tokens.nextToken();
if (token.length() > 1)
// char is a - add it to the list
single[singlecount++] = '-';
// add the current char to the list
single[singlecount++] = token.charAt(0);
}
}
if ((lower == null) && (single == null))
setCharset("a-zA-Z0-9");
}
}
相关推荐
实验五主要涵盖了AJAX技术的运用以及JSP验证码的开发，这两个知识点对于前端开发者来说是至关重要的。AJAX，即Asynchronous JavaScript and XML（异步JavaScript和XML），它允许网页在不重新加载整个页面的情况下与...
### jsp验证码刷新功能 在Web开发中，验证码（CAPTCHA）被广泛应用于表单提交、用户登录等场景，以防止自动化的恶意攻击或垃圾信息的提交。而在JSP技术中实现验证码的刷新功能，不仅可以提升用户体验，还能进一步...
【JSP验证码（Servlet）详解】 验证码是一种常用的安全机制，用于防止自动化的恶意程序，如机器人，进行非法操作。在Web开发中，JSP（JavaServer Pages）与Servlet结合使用可以实现动态生成并验证验证码的功能。这...
这个压缩包"5种JSP验证码的源代码.rar"提供的是五种不同的JSP验证码实现方式。下面我们将详细探讨这五种验证码的实现原理和关键知识点。 1. 图片验证码： 这是最常见的验证码类型，通过生成随机字符串并将其绘制到...
10. **安全注意事项**：尽管JSP验证码可以提供基础防护，但更高级的攻击手段（如OCR识别）可能仍能破解。因此，验证码只是多层安全措施中的一环，结合其他验证机制如IP限制、时间限制等，可以提高安全性。 以上就是...
JSP验证码+自动刷新功能,文件的image.jsp是负责生成验证码的,而display.jsp是负责显示效果.简单易用,平时会出现的异常都已经全部解决.
jsp验证码实现源代码,用jsp做注册验证码
在这个特定的案例中，我们关注的是一个JSP验证码的实现，其核心功能是生成4位随机数字并转化为图片进行用户验证。 验证码的主要目的是防止自动化程序（如机器人或恶意脚本）进行非法操作，比如注册、登录或提交表单...
在本例中，"JSP验证码生成需要的Jar包"提到了两个关键的Jar包：`pmiw.jar` 和 `taglibs-image.jar`。 1. **`pmiw.jar`**： 这个Jar包可能包含了用于生成验证码的相关类和方法。`pmiw`可能是某个第三方库或者项目的...
【jsp验证码程序】是一种在网页应用中用于防止自动机器人或者恶意攻击的重要安全机制。它通常由服务器生成，显示为一张包含随机字符或数字的图片，用户在提交表单时需要输入图片上显示的内容，以此来验证操作是由...
jsp验证码代码 在开发中验证码是比较常用到有效防止这种问题对某一个特定注册用户用特定程序破解方式进行不断的登陆尝试的方式。 此演示程序包括三个文件： 1.login.jsp:登录页面 2.code.jsp:生成验证码图片页面 3....
### jsp验证码——数字 #### 知识点详解 ##### JSP 验证码实现原理与过程 在本文档中，我们关注一个基于JavaServer Pages (JSP) 的数字验证码生成示例。此示例主要涉及到JSP页面的配置、Java图形处理库的使用以及...
jsp验证码，jsp中文验证码，数字验证码，汉字验证码
综上所述，JSP验证码代码涉及了图像处理、随机数生成、HTTP会话管理等多个技术点。理解这些知识点有助于开发者构建更安全、更易用的Web应用。在实际开发中，还可以结合现有的开源验证码库，如JCaptcha或Google的...
在`jsp验证码登录`这个主题中，我们将探讨如何在用户登录过程中引入验证码机制，增强系统的安全性。 首先，当用户尝试登录时，我们需要检查输入的用户名和密码。在JSP中，这可以通过`request.getParameter()`方法...
总之，理解和掌握JSP验证码的实现，不仅可以保护你的Web应用免受恶意攻击，还能帮助你更好地理解Web开发中的安全问题。通过下载、学习和实践提供的源码，你将能更深入地理解验证码技术及其在实际项目中的应用。
### JSP验证码生成 #### 1. 基本概念 验证码是一种防止自动化软件攻击的安全机制，常用于用户登录、表单提交等场景。JSP（Java Server Pages）是一种基于Java的技术，用于创建动态网页。在JSP中生成验证码通常涉及...
【JSP验证码技术详解】 验证码（CAPTCHA）是一种防止恶意自动化程序（如机器人）滥用服务的技术，它通过向用户展示一组难以由计算机自动识别的图像或文字，要求用户输入所见内容来验证其为真实的人。在JSP（Java...
**JSP验证码图片详解** 验证码（CAPTCHA）是一种防止恶意自动化程序（如机器人或爬虫）进行非法操作的安全机制。在网页开发中，JSP（Java Server Pages）被广泛用于生成动态的、难以通过机器自动识别的验证码图片。...