Java web登录验证码
时间: 2023-04-12 11:00:33 浏览: 61
Java web登录验证码是一种用于保护网站登录页面的安全机制,它可以防止恶意攻击者通过自动化程序暴力破解用户密码。验证码通常是一张包含随机字符或数字的图片,用户需要在登录页面上输入正确的验证码才能继续登录。在Java web开发中,可以使用第三方库或自己编写代码来生成和验证验证码。
相关问题
web自动化验证码识别java
web自动化验证码识别可以通过以下几种方式实现:
1. 使用第三方验证码识别工具,如Tess4J、Tesseract等。这些工具可以通过对验证码进行图像处理和字符识别,从而解析出验证码的内容。
2. 使用机器学习算法进行验证码识别。可以通过训练模型来识别不同类型的验证码,将验证码图像转换为特征向量,然后使用分类算法进行识别。
3. 使用图像处理算法进行验证码识别。可以通过图像处理技术,如二值化、去噪、边缘检测等,对验证码进行预处理,然后使用模板匹配或图像相似度比较来识别验证码。
Java Web实现登录加减乘除验证码完整代码
以下是一个简单的Java Web登录页面,包含加减乘除验证码功能的完整代码:
index.jsp:
```jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Login Page</title>
</head>
<body>
<h1>Login Page</h1>
<form action="login" method="post">
<label for="username">Username:</label>
<input type="text" id="username" name="username"><br><br>
<label for="password">Password:</label>
<input type="password" id="password" name="password"><br><br>
<label for="code">Code:</label>
<input type="text" id="code" name="code"><br>
<img src="code" onclick="this.src='code?'+Math.random()" alt="code"><br><br>
<input type="submit" value="Login">
</form>
</body>
</html>
```
login.java:
```java
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
/**
* Servlet implementation class LoginServlet
*/
@WebServlet("/login")
public class LoginServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public LoginServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
response.setContentType("image/jpeg");
int width = 100;
int height = 30;
String operators = "+-*/";
String code = "";
for (int i = 0; i < 4; i++) {
code += operators.charAt((int)(Math.random() * operators.length()));
}
int result = 0;
switch (code.charAt(0)) {
case '+':
result = Integer.parseInt(code.substring(1, 2)) + Integer.parseInt(code.substring(2, 3)) + Integer.parseInt(code.substring(3, 4));
break;
case '-':
result = Integer.parseInt(code.substring(1, 2)) - Integer.parseInt(code.substring(2, 3)) - Integer.parseInt(code.substring(3, 4));
break;
case '*':
result = Integer.parseInt(code.substring(1, 2)) * Integer.parseInt(code.substring(2, 3)) * Integer.parseInt(code.substring(3, 4));
break;
case '/':
result = Integer.parseInt(code.substring(1, 2)) / Integer.parseInt(code.substring(2, 3)) / Integer.parseInt(code.substring(3, 4));
break;
}
String expression = code.substring(1, 2) + code.charAt(0) + code.substring(2, 3) + code.charAt(0) + code.substring(3, 4) + "=";
String resultStr = expression + result;
request.getSession().setAttribute("code", result);
ImageUtil.generateVerifyCode(width, height, resultStr, response.getOutputStream());
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
String username = request.getParameter("username");
String password = request.getParameter("password");
String code = request.getParameter("code");
HttpSession session = request.getSession();
Integer verifyCode = (Integer)session.getAttribute("code");
if (verifyCode != null && verifyCode.toString().equals(code)) {
if (username.equals("admin") && password.equals("123456")) {
session.setAttribute("username", username);
response.sendRedirect("welcome.jsp");
} else {
session.setAttribute("error", "Invalid username or password!");
response.sendRedirect("index.jsp");
}
} else {
session.setAttribute("error", "Invalid verification code!");
response.sendRedirect("index.jsp");
}
}
}
```
ImageUtil.java:
```java
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import javax.imageio.ImageIO;
import javax.servlet.ServletOutputStream;
public class ImageUtil {
private static final String VERIFY_CODES = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
/**
* 生成随机验证码图片
* @param w
* @param h
* @param code
* @param sos
* @throws Exception
*/
public static void generateVerifyCode(int w, int h, String code, ServletOutputStream sos) throws Exception {
int verifySize = code.length();
BufferedImage image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
Graphics g = image.getGraphics();
g.setColor(new Color(200, 200, 255));
g.fillRect(0, 0, w, h);
g.setFont(new Font("Times New Roman", Font.ITALIC, 20));
// 绘制干扰线
for (int i = 0; i < 10; i++) {
int x = (int)(Math.random() * w);
int y = (int)(Math.random() * h);
int xl = (int)(Math.random() * 12);
int yl = (int)(Math.random() * 12);
g.setColor(new Color((int)(Math.random() * 255), (int)(Math.random() * 255), (int)(Math.random() * 255)));
g.drawLine(x, y, x + xl, y + yl);
}
// 绘制验证码
int codeX = 10;
for (int i = 0; i < verifySize; i++) {
codeX += 20;
g.setColor(new Color((int)(Math.random() * 255), (int)(Math.random() * 255), (int)(Math.random() * 255)));
g.drawString(String.valueOf(code.charAt(i)), codeX, 25);
}
g.dispose();
ImageIO.write(image, "JPEG", sos);
}
}
```
welcome.jsp:
```jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Welcome Page</title>
</head>
<body>
<h1>Welcome <%= session.getAttribute("username") %></h1>
</body>
</html>
```
在这个示例中,我们使用了一个Servlet来处理用户的登录请求,生成验证码并验证。我们使用了一个名为ImageUtil的工具类来生成验证码图像。用户输入的用户名和密码与预定义的值(在这种情况下为“admin”和“123456”)进行比较,如果匹配,则将用户名存储在会话中,并将用户重定向到欢迎页面。如果用户名或密码不正确或验证码不匹配,则将用户重定向回登录页面,并显示错误消息。