Java笔记-WEB算术验证码

这里和图片的字符串验证码差不多，只是要保留一个结果就可以了！

程序运行截图如下：

输入错误后，还是这个界面，但输入正确后：

程序截图如下：

maven项目，源码如下：

LoginServlet.java

import javax.jws.WebService;
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 java.io.IOException;

@WebServlet(value = "/login")
public class LoginServlet extends HttpServlet {

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

        this.doPost(request, response);
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        //得到数据
        String inCode = request.getParameter("inCode").toString().toLowerCase();
        String vailCode = request.getSession().getAttribute("vailCode").toString().toLowerCase();

        //验证是否正确
        if(inCode.equals(vailCode)){

            response.sendRedirect("index.jsp");
        }
        else{

            String url = request.getHeader("Referer");
            response.sendRedirect(url);
        }

    }
}

ValServlet.java

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 java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

@WebServlet(value = "/val")
public class ValServlet extends HttpServlet {

    private Random random = new Random();
    private int width = 140;
    private int height = 30;
    private int fontSize = 18;
    private String str = "+-*÷";
    private int value = -1; //结果

    private String randCode(){

        int one = random.nextInt(100);
        int two = random.nextInt(100);
        char op = str.charAt(random.nextInt(str.length()));

        switch (op){

            case '+':
                value = one + two;
                break;
            case '-':
                value = one - two;
                break;
            case  '*':
                value = one * two;
                break;
            case '÷':
                value = one / two;
                break;
        }
        return "" + one + op + two + "=?";
    }

    private Color randColor(){

        int r = random.nextInt(256);
        int g = random.nextInt(256);
        int b = random.nextInt(256);
        return new Color(r, g, b);
    }

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

        this.doPost(request, response);
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        //创建画板
        BufferedImage img = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

        //创建画笔
        Graphics2D pen = img.createGraphics();

        //生成内容
        String code = randCode();
        request.getSession().setAttribute("vailCode", value);

        //绘制区域
        pen.fillRect(0, 0, width, height);

        //绘制字体
        pen.setFont(new Font("微软雅黑", Font.BOLD, fontSize+random.nextInt(5)));

        //绘制字符
        for(int i = 0; i < code.length(); i++){

            pen.setColor(randColor());
            pen.drawString(code.charAt(i) + "", 5 + i * fontSize, (fontSize + height) / 2 + random.nextInt(5));
        }

        //绘制噪音线
        for(int i = 0; i < 2; i++){

            pen.setColor(randColor());
            pen.setStroke(new BasicStroke(3));
            pen.drawLine(random.nextInt(width / 2), random.nextInt(height),random.nextInt(width), random.nextInt(height));
        }

        //保存并发送
        ServletOutputStream out = response.getOutputStream();
        ImageIO.write(img, "png", out);
        out.flush();
        out.close();
    }
}

web.xml

<!DOCTYPE web-app PUBLIC
        "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
        "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
    <display-name>Archetype Created Web Application</display-name>
</web-app>

cal.jsp

<%--
  Created by IntelliJ IDEA.
  User: cff
  Date: 2020/1/31
  Time: 20:33
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>cal Title</title>
    <style type="text/css">
        .code_a{

            color: #0000ff;
            font-size: 12px;
            text-decoration: none;
            cursor: pointer;
        }
        #imgCode{

            cursor: pointer;
        }
    </style>
    <script type="text/javascript">
        function changeCode() {

            var imgCode = document.getElementById("imgCode");
            imgCode.src = "val?" + Math.random();
        }
    </script>
</head>
<body>
    <form action="login" method="post">
        <label>验证码：</label>
        <input type="text" id="inCode" name="inCode" />
        <img src = "val" align="center" id="imgCode"  οnclick="changeCode()" />
        <a class="code_a" οnclick="changeCode()">换一张</a><br />
        <input type="submit" value="登录" />
    </form>
</body>
</html>

index.jsp

<%--
  Created by IntelliJ IDEA.
  User: cff
  Date: 2020/1/31
  Time: 22:15
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
<h1>SUCCESS</h1>
</body>
</html>

porn.xml

<?xml version="1.0" encoding="UTF-8"?>
<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/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.example</groupId>
    <artifactId>calVailDemo</artifactId>
    <version>1.0-SNAPSHOT</version>

    <packaging>war</packaging>

    <dependencies>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>3.8.1</version>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.10</version>
            <scope>provided</scope>
        </dependency>


        <dependency>
            <groupId>commons-io</groupId>
            <artifactId>commons-io</artifactId>
            <version>2.5</version>
        </dependency>

        <dependency>
            <groupId>commons-fileupload</groupId>
            <artifactId>commons-fileupload</artifactId>
            <version>1.2.2</version>
        </dependency>

    </dependencies>

</project>