java web 验证码生成

先看看效果图：

一般需求应该够用了，有线条干扰线，斑点，字体小幅度的旋转。。

还没有与session挂钩上，所以只能用于简单的测试用例。

直接上代码，看代码注释。。。

  1 package com.act262.demo;
  2 
  3 import java.awt.Color;
  4 import java.awt.Font;
  5 import java.awt.Graphics;
  6 import java.awt.Graphics2D;
  7 import java.awt.image.BufferedImage;
  8 import java.io.IOException;
  9 import java.io.OutputStream;
 10 import java.util.Random;
 11 
 12 import javax.imageio.ImageIO;
 13 import javax.servlet.ServletException;
 14 import javax.servlet.annotation.WebServlet;
 15 import javax.servlet.http.HttpServlet;
 16 import javax.servlet.http.HttpServletRequest;
 17 import javax.servlet.http.HttpServletResponse;
 18 
 19 import sun.java2d.loops.DrawLine;
 20 
 21 /**
 22  * 输出随机的验证码
 23  */
 24 @WebServlet({ "/CheckCode", "/checkCode.do" })
 25 public class CheckCodeServlet extends HttpServlet {
 26     private static final long serialVersionUID = 1L;
 27 
 28     /* 宽度 */
 29     private final int WIDTH = 100;
 30     /* 高度 */
 31     private final int HEIGHT = 20;
 32     /* 生成验证码的个数 */
 33     private final int COUNT = 4;
 34     /* 干扰线条数 */
 35     private final int LINE_ROW = 6;
 36 
 37     /* 输出的基本码表，如果使用中文，则使用utf-8的码表，类似 ue234 ，而且应该使用常用字，避免出现偏僻字 */
 38     private final char[] BASECODE = { 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h',
 39             'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u',
 40             'v', 'w', 'x', 'y', 'z', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
 41             'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U',
 42             'V', 'W', 'X', 'Y', 'Z', '0', '1', '2', '3', '4', '5', '6', '7',
 43             '8', '9' };
 44     /* 随机数发生器 */
 45     private Random random;
 46     private BufferedImage image;
 47 
 48     // 写出数据
 49     private void write(OutputStream output) throws IOException {
 50         random = new Random();
 51 
 52         image = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);
 53         Graphics graphics = image.getGraphics();
 54 
 55         setBackground(graphics);
 56         drawBorder(graphics);
 57         drawDot(graphics);
 58         drawLine(graphics);
 59         drawString(graphics);
 60 
 61         ImageIO.write(image, "jpg", output);
 62     }
 63 
 64     //写字
 65     private void drawString(Graphics graphics) {
 66         StringBuffer sb = new StringBuffer();
 67         Font font = new Font("宋体", Font.BOLD, 18);
 68         graphics.setFont(font);
 69         graphics.setColor(Color.BLACK);
 70 
 71         for (int i = 0; i < COUNT; i++) {
 72             String ch = String
 73                     .valueOf(BASECODE[random.nextInt(BASECODE.length)]);
 74             sb.append(ch);
 75 
 76             // 设置位置
 77             int x = i * 20 + random.nextInt(12) + 10;
 78             int y = random.nextInt(HEIGHT / 3) + 12;
 79 
 80             // 旋转字体
 81             double theta = Math.PI / 180 * random.nextInt(20);
 82             // rotate(graphics, theta);
 83 
 84             graphics.drawString(ch, x, y);
 85 
 86             // 恢复。。
 87             // rotate(graphics, -theta);
 88         }
 89 
 90         System.out.println("验证码：" + sb.toString());
 91     }
 92 
 93     //旋转
 94     private void rotate(Graphics graphics, double theta) {
 95         ((Graphics2D) graphics).rotate(theta);
 96     }
 97 
 98     // 画随机线条
 99     private void drawLine(Graphics graphics) {
100         for (int i = 0; i < LINE_ROW; i++) {
101             int x1 = random.nextInt(WIDTH);
102             int y1 = random.nextInt(HEIGHT);
103             int x2 = random.nextInt(WIDTH);
104             int y2 = random.nextInt(HEIGHT);
105             setRandomColor(graphics);
106             graphics.drawLine(x1, y1, x2, y2);
107         }
108     }
109 
110     // 画斑点
111     private void drawDot(Graphics graphics) {
112         graphics.setColor(Color.red);
113         for (int i = 0; i < WIDTH; i++) {
114             int x = i;
115             int y = random.nextInt(HEIGHT);
116             int r = random.nextInt(2);
117             // graphics.fillOval(x, y, r, r);
118             graphics.drawOval(x, y, r, r);
119         }
120     }
121 
122     // 画边框
123     private void drawBorder(Graphics graphics) {
124         graphics.setColor(Color.BLACK);
125         graphics.drawRect(1, 1, WIDTH - 2, HEIGHT - 2);
126     }
127 
128     // 设置背景
129     private void setBackground(Graphics graphics) {
130         graphics.setColor(Color.WHITE);
131         graphics.fillRect(0, 0, WIDTH, HEIGHT);// 填充背景色
132     }
133 
134     // 设置随机的画笔颜色
135     private void setRandomColor(Graphics g) {
136         g.setColor(new Color(random.nextInt(255), random.nextInt(255), random
137                 .nextInt(255)));
138     }
139 
140     protected void doGet(HttpServletRequest request,
141             HttpServletResponse response) throws ServletException, IOException {
142 
143         response.setContentType("image/jpeg");
144         response.setHeader("Expires", "-1");
145         response.setHeader("Cache-Control", "no-cache");
146 
147         // 写出数据
148         write(response.getOutputStream());
149 
150     }
151 
152     protected void doPost(HttpServletRequest request,
153             HttpServletResponse response) throws ServletException, IOException {
154         // TODO Auto-generated method stub
155     }
156 
157 }

不足的是，这个验证码数量与字体大小还有图片的大小之间的关系比较难搞，我是一点一点计算调试出来的，有些时候图片上的字体会跑位，这就是画图的难点了。如果修改了数量，字体大小，这些位置关系得重新计算才行。

后续修改

还是這个验证码

  1 package com.act262.demo;
  2 
  3 import java.awt.Color;
  4 import java.awt.Font;
  5 import java.awt.Graphics;
  6 import java.awt.Graphics2D;
  7 import java.awt.image.BufferedImage;
  8 import java.io.IOException;
  9 import java.io.OutputStream;
 10 import java.util.Random;
 11 
 12 import javax.imageio.ImageIO;
 13 import javax.servlet.ServletException;
 14 import javax.servlet.annotation.WebServlet;
 15 import javax.servlet.http.HttpServlet;
 16 import javax.servlet.http.HttpServletRequest;
 17 import javax.servlet.http.HttpServletResponse;
 18 import javax.servlet.http.HttpSession;
 19 
 20 import sun.java2d.loops.DrawLine;
 21 
 22 /**
 23  * 输出随机的验证码
 24  */
 25 @WebServlet({ "/CheckCode", "/checkCode.jpg" })
 26 public class CheckCodeServlet extends HttpServlet {
 27     private static final long serialVersionUID = 1L;
 28 
 29     /* 宽度 */
 30     private final int WIDTH = 100;
 31     /* 高度 */
 32     private final int HEIGHT = 20;
 33     /* 生成验证码的个数 */
 34     private final int COUNT = 4;
 35     /* 干扰线条数 */
 36     private final int LINE_ROW = 6;
 37 
 38     /* 输出的基本码表，如果使用中文，则使用utf-8的码表，类似 ue234 ，而且应该使用常用字，避免出现偏僻字 */
 39     private final char[] BASECODE = { 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h',
 40             'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u',
 41             'v', 'w', 'x', 'y', 'z', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
 42             'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U',
 43             'V', 'W', 'X', 'Y', 'Z', '0', '1', '2', '3', '4', '5', '6', '7',
 44             '8', '9' };
 45 
 46     // 写出数据
 47     private void write(HttpServletRequest request, HttpServletResponse response)
 48             throws IOException {
 49         HttpSession session = request.getSession();
 50 
 51         BufferedImage image = new BufferedImage(WIDTH, HEIGHT,
 52                 BufferedImage.TYPE_INT_RGB);
 53         Graphics graphics = image.getGraphics();
 54 
 55         setBackground(graphics);
 56         drawBorder(graphics);
 57         drawDot(graphics);
 58         drawLine(graphics);
 59         drawString(graphics, session);
 60 
 61         // 写出数据流
 62         ImageIO.write(image, "jpg", response.getOutputStream());
 63 
 64     }
 65 
 66     // 写字
 67     private void drawString(Graphics graphics, HttpSession session) {
 68         StringBuffer sb = new StringBuffer();
 69         Random random = new Random();
 70 
 71         graphics.setFont(new Font("宋体", Font.BOLD, 18));
 72         graphics.setColor(Color.BLACK);
 73 
 74         for (int i = 0; i < COUNT; i++) {
 75             String ch = String
 76                     .valueOf(BASECODE[random.nextInt(BASECODE.length)]);
 77             sb.append(ch);
 78 
 79             // 设置位置
 80             int x = i * 20 + random.nextInt(12) + 10;
 81             int y = random.nextInt(HEIGHT / 3) + 12;
 82 
 83             // 旋转字体
 84             double theta = Math.PI / 180 * random.nextInt(20);
 85             // rotate(graphics, theta);
 86 
 87             graphics.drawString(ch, x, y);
 88 
 89             // 恢复。。
 90             // rotate(graphics, -theta);
 91         }
 92         session.setAttribute("checkCode", sb.toString());
 93 
 94         System.out.println("session:" + session + "   验证码：" + sb.toString());
 95     }
 96 
 97     // 旋转
 98     private void rotate(Graphics graphics, double theta) {
 99         ((Graphics2D) graphics).rotate(theta);
100     }
101 
102     // 画随机线条
103     private void drawLine(Graphics graphics) {
104         Random random = new Random();
105         for (int i = 0; i < LINE_ROW; i++) {
106             int x1 = random.nextInt(WIDTH);
107             int y1 = random.nextInt(HEIGHT);
108             int x2 = random.nextInt(WIDTH);
109             int y2 = random.nextInt(HEIGHT);
110             setRandomColor(graphics);
111             graphics.drawLine(x1, y1, x2, y2);
112         }
113     }
114 
115     // 画斑点
116     private void drawDot(Graphics graphics) {
117         Random random = new Random();
118         graphics.setColor(Color.red);
119         for (int i = 0; i < WIDTH; i++) {
120             int x = i;
121             int y = random.nextInt(HEIGHT);
122             int r = random.nextInt(2);
123             // graphics.fillOval(x, y, r, r);
124             graphics.drawOval(x, y, r, r);
125         }
126     }
127 
128     // 画边框
129     private void drawBorder(Graphics graphics) {
130         graphics.setColor(Color.BLACK);
131         graphics.drawRect(1, 1, WIDTH - 2, HEIGHT - 2);
132     }
133 
134     // 设置背景
135     private void setBackground(Graphics graphics) {
136         graphics.setColor(Color.WHITE);
137         graphics.fillRect(0, 0, WIDTH, HEIGHT);// 填充背景色
138     }
139 
140     // 设置随机的画笔颜色
141     private void setRandomColor(Graphics g) {
142         Random random = new Random();
143         g.setColor(new Color(random.nextInt(255), random.nextInt(255), random
144                 .nextInt(255)));
145     }
146 
147     protected void doGet(HttpServletRequest request,
148             HttpServletResponse response) throws ServletException, IOException {
149 
150         // 输出图片流的头信息
151         response.setContentType("image/jpeg");
152         response.setHeader("Expires", "-1");
153         response.setHeader("Cache-Control", "no-cache");
154 
155         // 写出数据
156         write(request, response);
157 
158     }
159 
160     protected void doPost(HttpServletRequest request,
161             HttpServletResponse response) throws ServletException, IOException {
162         // TODO Auto-generated method stub
163     }
164 
165 }

注册提交

package com.act262.demo;

import java.io.IOException;

import javax.servlet.RequestDispatcher;
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;

/**
 * Servlet implementation class RegisterServlet
 */
@WebServlet({ "/RegisterServlet", "/register.do" })
public class RegisterServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        HttpSession session = request.getSession();
        String checkCode = (String) session.getAttribute("checkCode");

        String paramsName = request.getParameter("name");
        String paramsPwd = request.getParameter("pwd");
        String paramsCheckCode = request.getParameter("checkCode").trim();

        // do somethines

        //
        response.setContentType("text/html;charset=utf-8");
        if (checkCode.equalsIgnoreCase(paramsCheckCode)) {
            System.out.println("check code ok");
            response.getWriter().write(
                    "尊敬的 <bold>" + paramsName + "</bold>用户，您的密码为：" + paramsPwd
                            + "<br/>验证码 OK");
        } else {
            response.getWriter().write(
                    "尊敬的 <bold>" + paramsName + "</bold>用户，您的密码为：" + paramsPwd
                            + "<br/>验证码 not OK");
        }
    }

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

}

jsp简单的界面

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>


</head>
<body>

    <div>

        <form action="register.do">
            <label>用户名：</label><input type="text" name="name" /></br> <label>密
                码：</label><input type="password" name="pwd" /></br> <label>验证码：</label><input
                type="text" name="checkCode" /><img src="checkCode.jpg"
                onclick=flushCheckCode(this) alt="点击刷新验证码" style="cursor: hand" /></br>
            <input type="submit" value="注册" />
        </form>

    </div>

    <script type="text/javascript">
        function flushCheckCode(obj) {
            obj.src = (obj.src + '?' + new Date())
        }
    </script>
</body>
</html>

這样子还是可以得，哈哈。。

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原文地址：https://www.cnblogs.com/act262/p/4104387.html