SpringMVC之获取随机验证码

来源：互联网发布：酷家乐在线装修软件编辑：程序博客网时间：2024/05/16 12:19

首先是Controller里面代码：

@RequestMapping(value = "random", method = RequestMethod.GET)

@ResponseBodypublic void Random(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {response.setContentType("image/jpeg");// 设置相应类型,告诉浏览器输出的内容为图片response.setHeader("Pragma", "No-cache");// 设置响应头信息，告诉浏览器不要缓存此内容response.setHeader("Cache-Control", "no-cache");response.setDateHeader("Expire", 0);RandomValidateCode randomValidateCode = new RandomValidateCode();try {randomValidateCode.getRandcode(request, response);// 输出图片方法} catch (Exception e) {e.printStackTrace();}}

然后是RandomValidateCode中代码：

package com.guide.util;import java.awt.Color;import java.awt.Font;import java.awt.Graphics;import java.awt.image.BufferedImage;import java.util.Random;import javax.imageio.ImageIO;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;public class RandomValidateCode { public static final String RANDOMCODEKEY = "RANDOMVALIDATECODEKEY";//放到session中的key    private Random random = new Random();    private String randString = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";//随机产生的字符串        private int width = 80;//图片宽    private int height = 40;//图片高    private int lineSize = 20;//干扰线数量    private int stringNum = 4;//随机产生字符数量    /*     * 获得字体     */    private Font getFont(){        return new Font("Fixedsys",Font.CENTER_BASELINE,18);    }    /*     * 获得颜色     */    private Color getRandColor(int fc,int bc){        if(fc > 255)            fc = 255;        if(bc > 255)            bc = 255;        int r = fc + random.nextInt(bc-fc-16);        int g = fc + random.nextInt(bc-fc-14);        int b = fc + random.nextInt(bc-fc-18);        return new Color(r,g,b);    }    /**     * 生成随机图片     */    public void getRandcode(HttpServletRequest request,            HttpServletResponse response) {        HttpSession session = request.getSession();        //BufferedImage类是具有缓冲区的Image类,Image类是用于描述图像信息的类        BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_BGR);        Graphics g = image.getGraphics();//产生Image对象的Graphics对象,改对象可以在图像上进行各种绘制操作        g.fillRect(0, 0, width, height);        g.setFont(new Font("Times New Roman",Font.ROMAN_BASELINE,18));        g.setColor(getRandColor(110, 133));        //绘制干扰线        for(int i=0;i<=lineSize;i++){            drowLine(g);        }        //绘制随机字符        String randomString = "";        for(int i=1;i<=stringNum;i++){            randomString=drowString(g,randomString,i);        }        session.setAttribute(RANDOMCODEKEY, randomString);        System.out.println(randomString);        g.dispose();        try {            ImageIO.write(image, "JPEG", response.getOutputStream());//将内存中的图片通过流动形式输出到客户端        } catch (Exception e) {            e.printStackTrace();        }    }    /*     * 绘制字符串     */    private String drowString(Graphics g,String randomString,int i){        g.setFont(getFont());        g.setColor(new Color(random.nextInt(101),random.nextInt(111),random.nextInt(121)));        String rand = String.valueOf(getRandomString(random.nextInt(randString.length())));        randomString +=rand;        g.translate(random.nextInt(3), random.nextInt(3));        g.drawString(rand, 13*i, 16);        return randomString;    }    /*     * 绘制干扰线     */    private void drowLine(Graphics g){        int x = random.nextInt(width);        int y = random.nextInt(height);        int xl = random.nextInt(13);        int yl = random.nextInt(15);        g.drawLine(x, y, x+xl, y+yl);    }    /*     * 获取随机的字符     */    public String getRandomString(int num){        return String.valueOf(randString.charAt(num));    }}

最后是页面代码：

<img onclick="changeCheckNum();" src="${ctx}/test/random?temp=<%=new java.util.Date().getTime()%>"id="checkImage" align="absbottom" alt="验证码" title="点击更换验证码" />function changeCheckNum(){var datt = new Date().getTime();$("#checkImage").attr("src","${ctx}/test/random?temp="+datt);}

值得注意的是：之前在js方法里面用“${ctx}”获取的时间总是与页面dom中加载的时间一致，导致点击更换验证码的时候并没有触发请求新的验证码图片。所以在js方法里面使用js的获取时间的代码（jstl的方式获取的时间是一样的0..0）。

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