Spring------练习生成验证码

验证码生成与验证

最新推荐文章于 2025-08-18 13:27:44 发布

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本文详细介绍了一个使用Java Servlet生成和验证验证码的示例。通过创建随机的四位数字验证码，并将其显示为图片，同时将验证码字符串存入Session以供后续登录验证使用。文章还展示了如何在登录时从Session中取出验证码进行比较，确保用户输入正确。

一.相关类

java.awt.Graphics
java.awt.image.BufferedImage
javax.imageio.ImageIO
java.awt.Color

package com.kennosaur.servlet;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
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;

@WebServlet("/validcode")
public class ValidCodeServlet extends HttpServlet{
	@Override
	protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		//创建一张图片
		BufferedImage image = new BufferedImage(200, 100, BufferedImage.TYPE_INT_RGB);
		
		//透明的玻璃
		//向画板上画内容之前必须先设置画笔
		Graphics2D gra = image.createGraphics();
		
		gra.setColor(Color.WHITE);
		//从哪个坐标开始填充,后两参数表示矩形区域
		gra.fillRect(0, 0, 200, 100);
		
		//随机产生四位数字
		List<Integer> randList = new ArrayList<Integer>();
		Random random = new Random();
		for (int i = 0; i < 4; i++) {
			randList.add(random.nextInt(10));
		}
		
		//设置颜色
		Color[] colors = new Color[] {Color.green,Color.blue,Color.cyan,Color.pink,Color.DARK_GRAY,Color.lightGray};
		
		//设置字体
		gra.setFont(new Font("宋体", Font.ITALIC|Font.BOLD, 30));
		for (int i = 0; i <randList.size(); i++) {
			gra.setColor(colors[random.nextInt(colors.length)]);
			gra.drawString(randList.get(i)+"", i*40, 70+random.nextInt(20));
			
		}
		
		for (int i = 0; i < 2; i++) {
			gra.setColor(colors[random.nextInt(colors.length)]);
			//画横线
			gra.drawLine(0, random.nextInt(101), 200, random.nextInt(101));
			
		}
		
		ServletOutputStream outputStream = resp.getOutputStream();
		//工具类---把图片刷到输出流中
		ImageIO.write(image, "jpg", outputStream);
		
		//把验证码放入到session中
		HttpSession session = req.getSession();
		session.setAttribute("code", ""+randList.get(0)+randList.get(1)+randList.get(2)+randList.get(3));
	}
}

在LoginServlet中,从Session中取出code进行比较

package com.kennosaur.servlet;

import java.io.IOException;

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 org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;

import com.kennosaur.pojo.Users;
import com.kennosaur.service.UsersService;
import com.kennosaur.service.impl.UsersServiceImpl;

@WebServlet("/login")
public class LoginServlet  extends HttpServlet{
	private UsersService usersService;
	
	@Override
	public void init() throws ServletException {
		  WebApplicationContext ac = WebApplicationContextUtils.getRequiredWebApplicationContext(getServletContext());
		  usersService = ac.getBean("usersServiceImpl", UsersServiceImpl.class);
	}
	
	@Override
	protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		req.setCharacterEncoding("utf-8");
		String code = req.getParameter("code");
		String codeSession = req.getSession().getAttribute("code").toString();
		if (codeSession.equals(code)) {
			String username = req.getParameter("username");
			String password = req.getParameter("password");
			Users users = new Users();
			users.setUsername(username);
			users.setPassword(password);
			Users login = usersService.login(users);
			if (login!=null) {
				resp.sendRedirect("main.jsp");
			}else {
				req.setAttribute("error", "用户名密码错误");
				req.getRequestDispatcher("index.jsp").forward(req, resp);
				
			}
		}else {
			req.setAttribute("error", "验证码错误");
			req.getRequestDispatcher("index.jsp").forward(req, resp);
		}
		
	}
}