SSM 实现登录验证码功能（附源码）

package com.utils;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 = "randomcode_key";//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 = 26;//图片高 private int lineSize = 40;//干扰线数量 private int stringNum = 4;//随机产生字符数量 /**  * 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);  //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  Graphics g = image.getGraphics();  g.fillRect(0, 0, width, height);  g.setFont(new Font("Times New Roman",Font.ROMAN_BASELINE,18));  g.setColor(getRandColor(160, 200));  //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.removeAttribute(RANDOMCODEKEY);  session.setAttribute(RANDOMCODEKEY, randomString);  g.dispose();  try {   //将内存中的图片通过流动形式输出到客户端   ImageIO.write(image, "JPEG", response.getOutputStream());  } catch (Exception e) {   e.printStackTrace();  } } /*  * 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); } /*  * 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)); }}

 /** * 获取生成验证码显示到 UI 界面 * @param request * @param response * @throws ServletException * @throws IOException */ @RequestMapping(value="/checkCode") public void checkCode(HttpServletRequest request, HttpServletResponse response)   throws ServletException, IOException { //设置相应类型,告诉浏览器输出的内容为图片  response.setContentType("image/jpeg");  //设置响应头信息，告诉浏览器不要缓存此内容  response.setHeader("pragma", "no-cache");  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();  } }

<img src="checkCode" alt="" width="100" height="32" class="passcode" style="height:43px;cursor:pointer;" onclick="this.src=this.src+'?'">