杂记（三）：jsp添加登录验证码

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绪论

杂七杂八，瞎记一下。

一、前端生成

index.jsp 代码

<%@ page language="java" contentType="text/html; charset=utf-8" import="java.util.*"    pageEncoding="utf-8"%><%    String contextPath = request.getContextPath();    String basePath = request.getScheme() + "://"            + request.getServerName() + ":" + request.getServerPort()            + contextPath + "/";%><!DOCTYPE html><html><head>    <base href="<%=basePath%>">    <meta http-equiv="Content-Type" content="text/html; charset=utf-8">    <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"><title>验证码展示页面</title></head><%    String numberCode = (String)request.getParameter("numberCode");    String rightcode = (String)session.getAttribute("rightcode");    if(numberCode != null && rightcode != null){        if(numberCode.equals(rightcode)){            out.println("验证码输入正确");        }else{            out.println("验证码输入不正确，请重新输入!");        }    }%><body>    <form action="" method="post">        <table>            <tr>                <td>用户名：</td>                <td><input type="text" name="username"/></td>                <td></td>            </tr>            <tr>                <td>密码：</td>                <td><input type="password" name="password"/></td>                <td></td>            </tr>            <tr>                <td>验证码：</td>                <td><input type="text" name="numberCode"/></td>                <td><img src="imgNumber.jsp"></td>            </tr>            <tr>                <td></td>                <td><input type="submit" value="登录"/></td>                <td></td>            </tr>        </table>    </form></body></html>

imgNumber.jsp 代码

<%@ page language="java" contentType="image/jpeg"     import="java.util.*,java.awt.*,java.awt.image.*,javax.imageio.*"    pageEncoding="utf-8"%><%!    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);    }%><%    // 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 = 60;    int height = 20;    BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);    // 创建图像    Graphics g = image.getGraphics();    // 生成随机对象    Random random = new Random();    // 设置背景色    g.setColor(getRandColor(200, 250));    g.fillRect(0, 0, width, height);    // 设置字体    g.setFont(new Font("Tines Nev Roman", Font.PLAIN, 18));    // 随机产生干扰线    g.setColor(getRandColor(160, 200));    for(int i = 0; i < 255; i++){        int x = random.nextInt(width);        int y = random.nextInt(height);        int x1 = random.nextInt(12);        int y1 = random.nextInt(12);    }    // 随机产生验证码，4位数字    String sRand = "";    for(int i = 0; i < 4; i++){        String rand = String.valueOf(random.nextInt(10));        sRand += rand;        // 将验证码显示到图像中        g.setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random.nextInt(110)));        g.drawString(rand, 13*i + 6, 16);    }    session.setAttribute("rightcode", sRand);    // 图像生效    g.dispose();    // 输出图像到页面    ImageIO.write(image, "JPEG", response.getOutputStream());    out.clear();    out = pageContext.pushBody();%>

运行结果：
这里写图片描述

这里写图片描述

二、后端生成

index.jsp 代码

<%@ page language="java" contentType="text/html; charset=utf-8"    pageEncoding="utf-8"%><%     String contextPath = request.getContextPath();    String basePath = request.getScheme() + "://"            + request.getServerName() + ":" + request.getServerPort()            + contextPath + "/";%><!DOCTYPE html><html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"><title>登录页</title><script type="text/javascript">function verificationCode(){    // 获取时间戳(只有ie某些版本不加时间戳，会发生浏览器缓存)//  var timestamp = (new Date()).valueOf();//  var timestamp = new Date().getTime();    $("#imgCode").attr("src", "<%=contextPath %>/system/imgNumber?timestamp=" + (new Date()).valueOf());}</script></head><body><div>    <table>        <tr>            <td>验证码：</td>            <td><input type="text" id="putNumber" name="putNumber" maxlength="8"></td>            <td><img id="imgCode" src="imgNumber" onclick="verificationCode()"></td>        </tr>    </table></div></body></html>

控制层访问方法

/** * 获取验证码图片 * @param request * @param response * @throws IOException */@RequestMapping("imgNumber")@ResponseBodypublic void toImgNumber(HttpServletRequest request, HttpServletResponse response) throws IOException{    VerificationCode.outputVerificationCode(request, response);}

验证码生成工具类

import java.awt.Color;import java.awt.Font;import java.awt.Graphics2D;import java.awt.image.BufferedImage;import java.io.IOException;import java.util.Random;import javax.servlet.ServletOutputStream;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import com.sun.image.codec.jpeg.JPEGCodec;import com.sun.image.codec.jpeg.JPEGImageEncoder;/** *  * 验证码生成工具类 * */public class VerificationCode {    // 随机字符字典    private static final char[] CHARS = { '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f', 'g',            'h', 'i', 'j', 'k', 'm', 'n', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 'A', 'B', 'C', 'D',            'E', 'F', 'G', 'H', 'J', 'K', 'L', 'M', 'N', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z' };    // 随机数    private static Random random = new Random();    /*     * 获取6位随机数     */    private static String getRandomString() {        StringBuffer buffer = new StringBuffer();        for (int i = 0; i < 6; i++) {            buffer.append(CHARS[random.nextInt(CHARS.length)]);        }        return buffer.toString();    }    /*     * 获取随机数颜色     */    private static Color getRandomColor() {        return new Color(random.nextInt(255), random.nextInt(255), random.nextInt(255));    }    /*     * 获取某颜色的反色     */    private static Color getReverseColor(Color c) {        return new Color(255 - c.getRed(), 255 - c.getGreen(), 255 - c.getBlue());    }    /*     * 生成验证码     */    public static void outputVerificationCode(HttpServletRequest request, HttpServletResponse response)            throws IOException {        response.setContentType("image/jpeg");        String randomString = getRandomString();        request.getSession(true).setAttribute("imgNumber", randomString);        int width = 100;        int height = 30;        Color color = getRandomColor();        Color reverse = getReverseColor(color);        BufferedImage bi = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);        Graphics2D g = bi.createGraphics();        g.setFont(new Font("Times New Roman", Font.BOLD, 16));        g.setColor(color);        g.fillRect(0, 0, width, height);        g.setColor(reverse);        g.drawString(randomString, 18, 20);        for (int i = 0, n = random.nextInt(100); i < n; i++) {            g.drawRect(random.nextInt(width), random.nextInt(height), 1, 1);        }        // 转成JPEG格式        ServletOutputStream out = response.getOutputStream();        JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);        encoder.encode(bi);        out.flush();    }}

运行结果：

这里写图片描述

（若有什么错误，请留言指正，3Q）

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