随机生成验证码

蔚落 2022-05-14 14:28 409阅读 0赞

//login.jsp加入
    
    <dt>验证码</dt>
    				<dd>
    					<input type="text" name="code" size="8" maxlength="4" /> 
    					<img align="middle" src="VerifyCodeServlet" title="看不清，点击换一张"
                     onclick="this.src=this.src+'?'+<%=new Date().getTime()%>"/><span>${errorMsg}</span>
    				</dd>

loginServlet添加

String loginCode=request.getParameter("code");
    		UserService service=new UserService();
    		boolean flagCode=service.isCodeEqual(loginCode, request);

service创建isCodeEqual方法

// 验证码验证
    		public boolean isCodeEqual(String loginCode, HttpServletRequest request) {
    			// TODO Auto-generated method stub
    			boolean flag = false;
    			// 获取session中的code
    			String sessionCode = (String) request.getSession().getAttribute("code");
    			System.out.println("session" + sessionCode);
    			System.out.println("login" + loginCode);
    			if (loginCode != null && sessionCode.equalsIgnoreCase(loginCode)) {
    				flag = true;
    			}
    			return flag;
    		}

随机四位验证码生成

package com.db.servlet;
    
    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.imageio.ImageIO;
    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;
    
    @WebServlet("/VerifyCodeServlet")
    public class VerifyCodeServlet extends HttpServlet {
    
    	private static final long serialVersionUID = 1L;
    
    	/**
    	 * @see HttpServlet#HttpServlet()
    	 */
    	public VerifyCodeServlet() {
    		super();
    		// TODO Auto-generated constructor stub
    	}
    
    	/**
    	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
    	 *      response)
    	 */
    	protected void doGet(HttpServletRequest request,
    			HttpServletResponse response) throws ServletException, IOException {
    		response.setContentType("image/jpeg");
    		// 设置页面不缓存
    		response.setHeader("Pragma", "No-cache");
    		response.setHeader("Cache-Control", "no-cache");
    		response.setDateHeader("Expires", 0);
    		// 在内存中创建图像
    		int width = 90;
    		int height = 35;
    		BufferedImage image = new BufferedImage(width, height,
    				BufferedImage.TYPE_INT_RGB);
    		// 获取图形上下文
    		Graphics g = image.getGraphics();
    		// 随机类
    		Random random = new Random();
    		// 设定背景
    		g.setColor(getRandColor(200, 250));
    		g.fillRect(0, 0, width, height);
    		// 设定字体
    		g.setFont(new Font("Times New Roman", Font.PLAIN, 30));
    		// 随机产生干扰线
    		g.setColor(getRandColor(160, 200));
    		for (int i = 0; i < 100; 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);
    		}
    		// 随机产生4位验证码
    		String[] codes = { "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", "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" };
    		String code = "";
    		for (int i = 0; i < 4; i++) {
    			String str = codes[random.nextInt(codes.length)];
    			code += str;
    			// 将认证码显示到图象中
    			g.setColor(new Color(50 + random.nextInt(110), 20 + random
    					.nextInt(110), 30 + 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(str, 18 * i + 13, 27); // 文字间距*i+距离左边距，上边距
    		}
    		HttpSession session = request.getSession();
    		// 将认证码存入SESSION
    		session.setAttribute("code", code);
    		// 图象生效
    		g.dispose();
    		// 输出图象到页面
    		ImageIO.write(image, "JPEG", response.getOutputStream());
    		// 加上下面代码,运行时才不会出现java.lang.IllegalStateException: getOutputStream() has
    		// already been called ..........等异常
    		response.getOutputStream().flush();
    		response.getOutputStream().close();
    		response.flushBuffer();
    	}
    
    	// 获取随机颜色
    	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);
    	}
    
    	/**
    	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
    	 *      response)
    	 */
    	protected void doPost(HttpServletRequest request,
    			HttpServletResponse response) throws ServletException, IOException {
    		// TODO Auto-generated method stub
    	}
    
    }

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