jsp中实现图片验证码

最新推荐文章于 2021-02-16 05:32:15 发布

iyvan

最新推荐文章于 2021-02-16 05:32:15 发布

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分类专栏： ★JavaEE 文章标签： jsp random exception import string html

本文链接：https://blog.youkuaiyun.com/yvan2008/article/details/4309659

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产生验证图片的ValidateImage类如下

package com.yuanli.util; import java.awt.Graphics; import java.awt.Image; import java.awt.image.BufferedImage; import java.util.Random; import java.awt.*; import javax.imageio.ImageIO; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; public class ValidateImage { private int width; private int height; private Random random = new Random(); private String randomStr=""; private HttpServletRequest request; private HttpServletResponse response; public ValidateImage(int width,int height,HttpServletRequest request,HttpServletResponse response) { this.width=width; this.height=height; this.request=request; this.response=response; this.setRandomStr(); } //获得产生的图像 public Image getImage()throws Exception { response.setContentType("image/jpeg"); // 设置页面不缓存 response.setHeader("Pragma","No-cache"); response.setHeader("Cache-Control","no-cache"); response.setDateHeader("Expires", 0); BufferedImage validate = new BufferedImage(width,height, BufferedImage.TYPE_INT_RGB); Graphics g = validate.getGraphics(); //设定背景色 g.setColor(getRandColor()); g.fillRect(0, 0, width, height); // 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到 g.setColor(getRandColor()); for (int i=0;i<155;i++) { int x = random.nextInt(width); int y = random.nextInt(height); int xl = random.nextInt(12); int yl = random.nextInt(12); g.drawLine(x,y,x+xl,y+yl); } g.setColor(getRandColor()); g.setFont(new Font("Times New Roman",Font.PLAIN,height)); g.drawString(getRandomStr(), width/20, height-height/4); //图像生成 g.dispose(); ImageIO.write(validate, "JPEG", response.getOutputStream()); return validate; } //产生随机数 private void setRandomStr() { for(;randomStr.length()<4;) { int x= random.nextInt(91); if(x<48||(x>57&&x<65)||x>90) { continue; } char c =(char)x; randomStr+=c; } } //取得随机字符串 public String getRandomStr() { HttpSession s = request.getSession(true); s.setAttribute("validate", randomStr); return randomStr; } //给定范围获得随机颜色 private Color getRandColor() { int r=random.nextInt(255); int g=random.nextInt(255); int b=random.nextInt(255); return new Color(r,g,b); } }

通过validateImage.jsp读取图片

<%@ page language="java" pageEncoding="ISO-8859-1"%> <%@ page import="com.yuanli.util.ValidateImage;"%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <img src="<%=new ValidateImage(100,30,request,response).getImage()%>"/>

其中100，30为设定图片的大小，之所以将request,response传到类ValidateImage中是为了将类ValidateImage中通过getRandomStr()方法的到随机字符串写入到session中（产生的图片中的字符串就是通过该方法得到的），以便于与用户输入的验证码校验。

在登陆页面中加入

防止src被过滤掉，特改为s.rc

加入的超链接就是为了实现点击图片后刷新更换图片