下面imagecode方法是一个生成图形验证码的请求，checkcode方法实现了对这个图形验证码的验证。从验证码的生成到验证的过程中，验证码是通过Session来保存的，并且设定一个验证码的最长有效时间为5分钟。验证码的生成规则是从0~9的数字中，随机产生一个4位数，并增加一些干扰元素，最终组合成为一个图形输出
1、验证码生成类
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.OutputStream;import java.util.HashMap;
import java.util.Map;import java.util.Random;
public class ImageCode {
private static char mapTable[] = {
'0', '1', '2', '3', '4', '5',
'6', '7', '8', '9', '0', '1',
'2', '3', '4', '5', '6', '7',
'8', '9'};
public static Map<String, Object> getImageCode(int width, int height, OutputStream os) {
Map<String,Object> returnMap = new HashMap<String, Object>();
if (width <= 0) width = 60;
if (height <= 0) height = 20;
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
// 获取图形上下文
Graphics g = image.getGraphics();
//生成随机类
Random random = new Random();
// 设定背景色
g.setColor(getRandColor(200, 250));
g.fillRect(0, 0, width, height);
//设定字体
g.setFont(new Font("Times New Roman", Font.PLAIN, 18));
// 随机产生168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(160, 200));
for (int i = 0; i < 168; 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);
}
//取随机产生的码
String strEnsure = "";
//4代表4位验证码,如果要生成更多位的认证码,则加大数值
for (int i = 0; i < 4; ++i) {
strEnsure += mapTable[(int) (mapTable.length * Math.random())];
// 将认证码显示到图象中
g.setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random.nextInt(110)));
//直接生成
String str = strEnsure.substring(i, i + 1);
g.drawString(str, 13 * i + 6, 16);
}
// 释放图形上下文
g.dispose();
returnMap.put("image",image);
returnMap.put("strEnsure",strEnsure);
return returnMap;
}
//给定范围获得随机颜色
static Color getRandColor(int fc, int bc) {
Random random = new Random();
if (fc > 255) fc = 255;
if (bc > 255) bc = 255;
int r = fc + random.nextInt(bc - fc);
int g = fc + random.nextInt(bc - fc);
int b = fc + random.nextInt(bc - fc);
return new Color(r, g, b);
}
}
2、获取验证码API
@RequestMapping(value = "/images/imagecode")
public String imagecode(HttpServletRequest request, HttpServletResponse response) throws Exception {
OutputStream os = response.getOutputStream();
Map<String,Object> map = ImageCode.getImageCode(60, 20, os);
String simpleCaptcha = "simpleCaptcha";
request.getSession().setAttribute(simpleCaptcha, map.get("strEnsure").toString().toLowerCase());
request.getSession().setAttribute("codeTime",new Date().getTime());
try {
ImageIO.write((BufferedImage) map.get("image"), "JPEG", os);
} catch (IOException e) {
return "";
}
return null;
}
3、验证验证码API
@RequestMapping(value = "/checkcode")
@ResponseBody
public String checkcode(HttpServletRequest request, HttpSession session) throws Exception {
String checkCode = request.getParameter("checkCode");
Object cko = session.getAttribute("simpleCaptcha") ; //验证码对象
if(cko == null){
request.setAttribute("errorMsg", "验证码已失效，请重新输入！");
return "验证码已失效，请重新输入！";
}
String captcha = cko.toString();
Date now = new Date();
Long codeTime = Long.valueOf(session.getAttribute("codeTime")+"");
if(StringUtils.isEmpty(checkCode) || captcha == null || !(checkCode.equalsIgnoreCase(captcha))) {
request.setAttribute("errorMsg", "验证码错误！");
return "验证码错误！";
} else if ((now.getTime()-codeTime)/1000/60>5) {
//验证码有效时长为5分钟
request.setAttribute("errorMsg", "验证码已失效，请重新输入！");
return "验证码已失效，请重新输入！";
}else {
session.removeAttribute("simpleCaptcha");
return "1";
}
}