Spring Boot 验证码的生成和验证详解

前言

本文介绍的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";
 }
}

总结

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