以前跟着写的一段获取验证码的servlet,当时觉得还挺麻烦的要自己画,最近找到了一个封装好的工具类记录一下

先看看以前写的获取验证码的servlet

 

package cn.itcast.travel.web.servlet;

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

/**
 * 验证码
 */
@WebServlet("/checkCode")
public class CheckCodeServlet extends HttpServlet {
    public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
        
        //服务器通知浏览器不要缓存
        response.setHeader("pragma","no-cache");
        response.setHeader("cache-control","no-cache");
        response.setHeader("expires","0");
        
        //在内存中创建一个长80，宽30的图片，默认黑色背景
        //参数一：长
        //参数二：宽
        //参数三：颜色
        int width = 80;
        int height = 30;
        BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
        
        //获取画笔
        Graphics g = image.getGraphics();
        //设置画笔颜色为灰色
        g.setColor(Color.GRAY);
        //填充图片
        g.fillRect(0,0, width,height);
        
        //产生4个随机验证码，12Ey
        String checkCode = getCheckCode();
        //将验证码放入HttpSession中
        request.getSession().setAttribute("CHECKCODE_SERVER",checkCode);
        
        //设置画笔颜色为黄色
        g.setColor(Color.YELLOW);
        //设置字体的小大
        g.setFont(new Font("黑体",Font.BOLD,24));
        //向图片上写入验证码
        g.drawString(checkCode,15,25);
        
        //将内存中的图片输出到浏览器
        //参数一：图片对象
        //参数二：图片的格式，如PNG,JPG,GIF
        //参数三：图片输出到哪里去
        ImageIO.write(image,"PNG",response.getOutputStream());
    }
    /**
     * 产生4位随机字符串 
     */
    private String getCheckCode() {
        String base = "0123456789ABCDEFGabcdefg";
        int size = base.length();
        Random r = new Random();
        StringBuffer sb = new StringBuffer();
        for(int i=1;i<=4;i++){
            //产生0到size-1的随机值
            int index = r.nextInt(size);
            //在base字符串中获取下标为index的字符
            char c = base.charAt(index);
            //将c放入到StringBuffer中去
            sb.append(c);
        }
        return sb.toString();
    }
    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request,response);
    }
}

 

下面是工具类 返回值是一个String 类型的code 还有一个BufferedImage image 对象

在Controller层用ImageIO.write(image,"png",response.getOutputStream)返回，把code存入Session中

 

 

package com.mkx_test.utils;

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

public class CodeImageUtil {
    private static final char[] chars = {
            '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
            'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'm', 'n',
            'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
            'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'J', 'K', 'L', 'M', 'N',
            'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z'
    };
    // 字符数量
    private static final int SIZE = 4;
    // 干扰线数量
    private static final int LINES = 5;
    // 宽度
    private static final int WIDTH = 100;
    // 高度
    private static final int HEIGHT = 40;
    // 字体大小
    private static final int FONT_SIZE = 30;

    public static Object[] createImage(){
        StringBuffer sb = new StringBuffer();
        //创建空白图片
        BufferedImage image = new BufferedImage(WIDTH,HEIGHT,BufferedImage.TYPE_INT_RGB);
        //获取图片画笔
        Graphics graphics = image.getGraphics();
        //设置画笔颜色
        graphics.setColor(new Color(0xEDEDED));
        //绘制矩形背景
        graphics.fillRect(0,0,WIDTH,HEIGHT);
        //画随机字符
        Random random = new Random();
        for (int i=0;i<SIZE;i++){
            //获取随机字符索引
            int j = random.nextInt(chars.length);
            //设置随机颜色
            graphics.setColor(getRandonColor());
            //设置字体大小
            graphics.setFont(new Font(null,Font.BOLD+Font.ITALIC,FONT_SIZE));
            //画字符
            graphics.drawString(chars[j] + "",i * (WIDTH)/SIZE + 1,HEIGHT*2/3);
            //记录字符
            sb.append(chars[j]);
        }
        //画干扰线
        for (int i = 0;i<LINES;i++){
            //设置随机颜色
            graphics.setColor(getRandonColor());
            //随机画线
            graphics.drawLine(random.nextInt(WIDTH),random.nextInt(HEIGHT),random.nextInt(WIDTH),random.nextInt(HEIGHT));
        }
        //返回验证码和图片
        return new Object[]{sb.toString(),image};
    }

    /**
     * 随机取色
     */
    private static Color getRandonColor() {
        Random random = new Random();
        Color color = new Color(random.nextInt(256),random.nextInt(256),random.nextInt(256));
        return color;
    }

//    public static void main(String[] args) throws IOException {
//        Object[] objs = createImage();
//        BufferedImage image = (BufferedImage) objs[1];
//        OutputStream os = new FileOutputStream("d:/1.png");
//        ImageIO.write(image, "png", os);
//        os.close();
//    }
}

 

Controller层中

 

 /*
    * 加载验证码
    */
    @RequestMapping("/getCode")
    public void getCode(HttpServletRequest request,HttpServletResponse response) throws IOException {
        Object[] objs = CodeImageUtil.createImage();
        String code = objs[0].toString();
        System.out.println("系统生成的验证码是:"+code);
        //image对象
        BufferedImage image =(BufferedImage) objs[1];
        //将内存中的图片输出到浏览器
        //参数一：图片对象
        //参数二：图片的格式，如PNG,JPG,GIF
        //参数三：图片输出到哪里去
        ImageIO.write(image,"png",response.getOutputStream());
        request.getSession().setAttribute("code",code);
    }

 

视图层jsp中：注意加上点击事件的时间戳,每次都能换到不同的验证码图片

<div class="form-group">
                    <label for="codeInp">验证码</label>
                    <input type="text" id="codeInp" name="code"  >
                    <img id="code" src="${pageContext.request.contextPath}/user/getCode"  onclick="flushCode(this)">
                </div>

<script>
        function flushCode(obj) {
            let time = new Date().getTime();
            obj.src="${pageContext.request.contextPath}/user/getCode?"+time;
        }
    </script>