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servlet生成随机验证码

Servlet 生成 随机 验证码
2023-09-11 14:18:37 时间

 

直接上项目截图

一个简单的maven小demo

 

 

 

 

一 pom文件

<?xml version="1.0" encoding="UTF-8"?>
<!--
  Licensed to the Apache Software Foundation (ASF) under one
  or more contributor license agreements.  See the NOTICE file
  distributed with this work for additional information
  regarding copyright ownership.  The ASF licenses this file
  to you under the Apache License, Version 2.0 (the
  "License"); you may not use this file except in compliance
  with the License.  You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing,
  software distributed under the License is distributed on an
  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  KIND, either express or implied.  See the License for the
  specific language governing permissions and limitations
  under the License.
-->
<!-- $Id: pom.xml 642118 2008-03-28 08:04:16Z reinhard $ -->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">

  <modelVersion>4.0.0</modelVersion>
  <packaging>war</packaging>

  <name>code</name>
  <groupId>com.cyf</groupId>
  <artifactId>code</artifactId>
  <version>1.0-SNAPSHOT</version>

  <build>
    <finalName>${project.artifactId}</finalName>
    <resources>
      <resource>
        <directory>src/main/resources</directory>
      </resource>
      <resource>
        <directory>src/main/webapp</directory>
        <filtering>true</filtering>
        <includes>
          <include>**/*.*</include>
        </includes>
        <targetPath>${project.build.directory}/webapp</targetPath>
      </resource>
    </resources>
    <plugins>
      <plugin>
        <groupId>org.apache.tomcat.maven</groupId>
        <artifactId>tomcat7-maven-plugin</artifactId>
        <version>2.1</version>
        <configuration>
          <path>/${project.artifactId}</path>
          <port>8086</port>
          <uriEncoding>UTF-8</uriEncoding>
          <warSourceDirectory>${project.build.directory}/webapp</warSourceDirectory>
        </configuration>
      </plugin>
      <plugin>
        <groupId>org.mybatis.generator</groupId>
        <artifactId>mybatis-generator-maven-plugin</artifactId>
        <version>1.3.2</version>
      </plugin>
    </plugins>
  </build>
  <dependencies>
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>jstl</artifactId>
      <version>1.1.2</version>
    </dependency>
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>3.1.0</version>
      <scope>provided</scope>
    </dependency>
  </dependencies>

</project>

 

二index.jsp展示页面

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
    <title>在Form表单中使用验证码</title>
    <script type="text/javascript">
        //刷新验证码
        function changeImg(obj,createTypeFlag){
            document.getElementById(obj.id).src="${pageContext.request.contextPath}/servlet/DrawImage?createTypeFlag="+createTypeFlag+"&"+Math.random();
        }
    </script>
</head>

<body>
<form action="${pageContext.request.contextPath}/servlet/CheckServlet" method="post">
    <%--数字字母混合验证码：<input type="text" name="validateCode"/>--%>
    <%--<img alt="验证码看不清，换一张" src="${pageContext.request.contextPath}/servlet/DrawImage" id="validateCodeImg1" onclick="changeImg(this,'nl')">--%>
    <%--<br/>--%>
    <%--中文验证码：<input type="text" name="validateCode"/>--%>
    <%--<img alt="验证码看不清，换一张" src="${pageContext.request.contextPath}/servlet/DrawImage?createTypeFlag=ch" id="validateCodeImg2" onclick="changeImg(this,'ch')">--%>
    <%--<br/>--%>
    <%--英文验证码：<input type="text" name="validateCode"/>--%>
    <%--<img alt="验证码看不清，换一张" src="${pageContext.request.contextPath}/servlet/DrawImage?createTypeFlag=l" id="validateCodeImg3" onclick="changeImg(this,'l')">--%>
    <%--<br/>--%>
    数字验证码：<input type="text" name="validateCode"/>
    <img alt="验证码看不清，换一张" src="${pageContext.request.contextPath}/servlet/DrawImage?createTypeFlag=n" id="validateCodeImg4" onclick="changeImg(this,'n')">
    <br/>
    <input type="submit" value="提交">
</form>
</body>
</html>

 

三 web.xml文件

<?xml version="1.0" encoding="UTF-8"?>

<web-app version="2.4"
         xmlns="http://java.sun.com/xml/ns/j2ee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">

  <display-name></display-name>
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
  <servlet>
    <servlet-name>Code</servlet-name>
    <servlet-class>com.DrawImage</servlet-class>
  </servlet>

  <servlet-mapping>
    <servlet-name>Code</servlet-name>
    <url-pattern>/servlet/DrawImage</url-pattern>
  </servlet-mapping>


  <servlet>
    <servlet-name>check</servlet-name>
    <servlet-class>com.CheckServlet</servlet-class>
  </servlet>

  <servlet-mapping>
    <servlet-name>check</servlet-name>
    <url-pattern>/servlet/CheckServlet</url-pattern>
  </servlet-mapping>
</web-app>

四 DrawImage

package com;


import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

/**
 * 生成随机图片，用来作为验证码
 */
public class DrawImage extends HttpServlet {
    private static final long serialVersionUID = 3038623696184546092L;

    public static final int WIDTH = 120;//生成的图片的宽度
    public static final int HEIGHT = 30;//生成的图片的高度

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        this.doPost(request, response);
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        String createTypeFlag = request.getParameter("createTypeFlag");//接收客户端传递的createTypeFlag标识
        //1.在内存中创建一张图片
        BufferedImage bi = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);
        //2.得到图片
        Graphics g = bi.getGraphics();
        //3.设置图片的背影色
        setBackGround(g);
        //4.设置图片的边框
        setBorder(g);
        //5.在图片上画干扰线
        drawRandomLine(g);
        //6.写在图片上随机数
        //String random = drawRandomNum((Graphics2D) g,"ch");//生成中文验证码图片
        //String random = drawRandomNum((Graphics2D) g,"nl");//生成数字和字母组合的验证码图片
        //String random = drawRandomNum((Graphics2D) g,"n");//生成纯数字的验证码图片
        //String random = drawRandomNum((Graphics2D) g,"l");//生成纯字母的验证码图片
        String random = drawRandomNum((Graphics2D) g, createTypeFlag);//根据客户端传递的createTypeFlag标识生成验证码图片
        //7.将随机数存在session中
        request.getSession().setAttribute("checkcode", random);
        //8.设置响应头通知浏览器以图片的形式打开
        response.setContentType("image/jpeg");//等同于response.setHeader("Content-Type", "image/jpeg");
        //9.设置响应头控制浏览器不要缓存
        response.setDateHeader("expries", -1);
        response.setHeader("Cache-Control", "no-cache");
        response.setHeader("Pragma", "no-cache");
        //10.将图片写给浏览器
        ImageIO.write(bi, "jpg", response.getOutputStream());
    }

    /**
     * 设置图片的背景色
     *
     * @param g
     */
    private void setBackGround(Graphics g) {
        // 设置颜色
        g.setColor(Color.WHITE);
        // 填充区域
        g.fillRect(0, 0, WIDTH, HEIGHT);
    }

    /**
     * 设置图片的边框
     *
     * @param g
     */
    private void setBorder(Graphics g) {
        // 设置边框颜色
        g.setColor(Color.GRAY);
        // 边框区域
        g.drawRect(1, 1, WIDTH - 2, HEIGHT - 2);
    }

    /**
     * 在图片上画随机线条
     *
     * @param g
     */
    private void drawRandomLine(Graphics g) {
        // 设置颜色
        g.setColor(Color.YELLOW);
        // 设置线条个数并画线
        for (int i = 0; i < 5; i++) {
            int x1 = new Random().nextInt(WIDTH);
            int y1 = new Random().nextInt(HEIGHT);
            int x2 = new Random().nextInt(WIDTH);
            int y2 = new Random().nextInt(HEIGHT);
            g.drawLine(x1, y1, x2, y2);
        }
    }

    /**
     * 画随机字符
     *
     * @param g
     * @param createTypeFlag
     * @return String... createTypeFlag是可变参数，
     * Java1.5增加了新特性：可变参数：适用于参数个数不确定，类型确定的情况，java把可变参数当做数组处理。注意：可变参数必须位于最后一项
     */
    private String drawRandomNum(Graphics2D g, String... createTypeFlag) {
        // 设置颜色
        g.setColor(Color.RED);
        // 设置字体
        g.setFont(new Font("宋体", Font.BOLD, 20));
        //常用的中国汉字
        String baseChineseChar = "\u7684\u4e00\u4e86\u662f\u6211\u4e0d\u5728\u4eba\u4eec\u6709\u6765\u4ed6\u8fd9\u4e0a\u7740\u4e2a\u5730\u5230\u5927\u91cc\u8bf4\u5c31\u53bb\u5b50\u5f97\u4e5f\u548c\u90a3\u8981\u4e0b\u770b\u5929\u65f6\u8fc7\u51fa\u5c0f\u4e48\u8d77\u4f60\u90fd\u628a\u597d\u8fd8\u591a\u6ca1\u4e3a\u53c8\u53ef\u5bb6\u5b66\u53ea\u4ee5\u4e3b\u4f1a\u6837\u5e74\u60f3\u751f\u540c\u8001\u4e2d\u5341\u4ece\u81ea\u9762\u524d\u5934\u9053\u5b83\u540e\u7136\u8d70\u5f88\u50cf\u89c1\u4e24\u7528\u5979\u56fd\u52a8\u8fdb\u6210\u56de\u4ec0\u8fb9\u4f5c\u5bf9\u5f00\u800c\u5df1\u4e9b\u73b0\u5c71\u6c11\u5019\u7ecf\u53d1\u5de5\u5411\u4e8b\u547d\u7ed9\u957f\u6c34\u51e0\u4e49\u4e09\u58f0\u4e8e\u9ad8\u624b\u77e5\u7406\u773c\u5fd7\u70b9\u5fc3\u6218\u4e8c\u95ee\u4f46\u8eab\u65b9\u5b9e\u5403\u505a\u53eb\u5f53\u4f4f\u542c\u9769\u6253\u5462\u771f\u5168\u624d\u56db\u5df2\u6240\u654c\u4e4b\u6700\u5149\u4ea7\u60c5\u8def\u5206\u603b\u6761\u767d\u8bdd\u4e1c\u5e2d\u6b21\u4eb2\u5982\u88ab\u82b1\u53e3\u653e\u513f\u5e38\u6c14\u4e94\u7b2c\u4f7f\u5199\u519b\u5427\u6587\u8fd0\u518d\u679c\u600e\u5b9a\u8bb8\u5feb\u660e\u884c\u56e0\u522b\u98de\u5916\u6811\u7269\u6d3b\u90e8\u95e8\u65e0\u5f80\u8239\u671b\u65b0\u5e26\u961f\u5148\u529b\u5b8c\u5374\u7ad9\u4ee3\u5458\u673a\u66f4\u4e5d\u60a8\u6bcf\u98ce\u7ea7\u8ddf\u7b11\u554a\u5b69\u4e07\u5c11\u76f4\u610f\u591c\u6bd4\u9636\u8fde\u8f66\u91cd\u4fbf\u6597\u9a6c\u54ea\u5316\u592a\u6307\u53d8\u793e\u4f3c\u58eb\u8005\u5e72\u77f3\u6ee1\u65e5\u51b3\u767e\u539f\u62ff\u7fa4\u7a76\u5404\u516d\u672c\u601d\u89e3\u7acb\u6cb3\u6751\u516b\u96be\u65e9\u8bba\u5417\u6839\u5171\u8ba9\u76f8\u7814\u4eca\u5176\u4e66\u5750\u63a5\u5e94\u5173\u4fe1\u89c9\u6b65\u53cd\u5904\u8bb0\u5c06\u5343\u627e\u4e89\u9886\u6216\u5e08\u7ed3\u5757\u8dd1\u8c01\u8349\u8d8a\u5b57\u52a0\u811a\u7d27\u7231\u7b49\u4e60\u9635\u6015\u6708\u9752\u534a\u706b\u6cd5\u9898\u5efa\u8d76\u4f4d\u5531\u6d77\u4e03\u5973\u4efb\u4ef6\u611f\u51c6\u5f20\u56e2\u5c4b\u79bb\u8272\u8138\u7247\u79d1\u5012\u775b\u5229\u4e16\u521a\u4e14\u7531\u9001\u5207\u661f\u5bfc\u665a\u8868\u591f\u6574\u8ba4\u54cd\u96ea\u6d41\u672a\u573a\u8be5\u5e76\u5e95\u6df1\u523b\u5e73\u4f1f\u5fd9\u63d0\u786e\u8fd1\u4eae\u8f7b\u8bb2\u519c\u53e4\u9ed1\u544a\u754c\u62c9\u540d\u5440\u571f\u6e05\u9633\u7167\u529e\u53f2\u6539\u5386\u8f6c\u753b\u9020\u5634\u6b64\u6cbb\u5317\u5fc5\u670d\u96e8\u7a7f\u5185\u8bc6\u9a8c\u4f20\u4e1a\u83dc\u722c\u7761\u5174\u5f62\u91cf\u54b1\u89c2\u82e6\u4f53\u4f17\u901a\u51b2\u5408\u7834\u53cb\u5ea6\u672f\u996d\u516c\u65c1\u623f\u6781\u5357\u67aa\u8bfb\u6c99\u5c81\u7ebf\u91ce\u575a\u7a7a\u6536\u7b97\u81f3\u653f\u57ce\u52b3\u843d\u94b1\u7279\u56f4\u5f1f\u80dc\u6559\u70ed\u5c55\u5305\u6b4c\u7c7b\u6e10\u5f3a\u6570\u4e61\u547c\u6027\u97f3\u7b54\u54e5\u9645\u65e7\u795e\u5ea7\u7ae0\u5e2e\u5566\u53d7\u7cfb\u4ee4\u8df3\u975e\u4f55\u725b\u53d6\u5165\u5cb8\u6562\u6389\u5ffd\u79cd\u88c5\u9876\u6025\u6797\u505c\u606f\u53e5\u533a\u8863\u822c\u62a5\u53f6\u538b\u6162\u53d4\u80cc\u7ec6";
        //数字和字母的组合
        String baseNumLetter = "0123456789ABCDEFGHJKLMNOPQRSTUVWXYZ";
        //纯数字
        String baseNum = "0123456789";
        //纯字母
        String baseLetter = "ABCDEFGHJKLMNOPQRSTUVWXYZ";
        //createTypeFlag[0]==null表示没有传递参数
        if (createTypeFlag.length > 0 && null != createTypeFlag[0]) {
            if (createTypeFlag[0].equals("ch")) {
                // 截取汉字
                return createRandomChar(g, baseChineseChar);
            } else if (createTypeFlag[0].equals("nl")) {
                // 截取数字和字母的组合
                return createRandomChar(g, baseNumLetter);
            } else if (createTypeFlag[0].equals("n")) {
                // 截取数字
                return createRandomChar(g, baseNum);
            } else if (createTypeFlag[0].equals("l")) {
                // 截取字母
                return createRandomChar(g, baseLetter);
            }
        } else {
            // 默认截取数字和字母的组合
            return createRandomChar(g, baseNumLetter);
        }

        return "";
    }

    /**
     * 创建随机字符
     *
     * @param g
     * @param baseChar
     * @return 随机字符
     */
    private String createRandomChar(Graphics2D g, String baseChar) {
        StringBuffer sb = new StringBuffer();
        int x = 5;
        String ch = "";
        // 控制字数
        for (int i = 0; i < 4; i++) {
            // 设置字体旋转角度
            int degree = new Random().nextInt() % 30;
            ch = baseChar.charAt(new Random().nextInt(baseChar.length())) + "";
            sb.append(ch);
            // 正向角度
            g.rotate(degree * Math.PI / 180, x, 20);
            g.drawString(ch, x, 20);
            // 反向角度
            g.rotate(-degree * Math.PI / 180, x, 20);
            x += 30;
        }
        return sb.toString();
    }
}

五 CheckServlet

package com;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
 * @author gacl0
 * 服务器端接收到验证码后的处理
 */
public class CheckServlet extends HttpServlet {
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        String clientCheckcode = request.getParameter("validateCode");//接收客户端浏览器提交上来的验证码
        String serverCheckcode = (String) request.getSession().getAttribute("checkcode");//从服务器端的session中取出验证码
        if (clientCheckcode.equals(serverCheckcode)) {//将客户端验证码和服务器端验证比较，如果相等，则表示验证通过
            System.out.println("验证码验证通过！");
        } else {
            System.out.println("验证码验证失败！");
        }
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }

}

 效果图

 

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