前言：这篇文章里面的代码是基于spring boot的，直接拷贝可用，可以先用了再去理解里面原理
1.请求获取验证码图片的API：CaptchaController.java
**
* Author: SamGroves
*
* Description: 该Api能够直接获取到验证码图片
*
* Date: 2017/8/29
*/
@Controller
@RequestMapping("/api")
public class CaptchaController {
/**
* 用于生成带四位数字验证码的图片
*/
@RequestMapping(value = "/captcha")
@ResponseBody
public String imagecode(HttpServletRequest request, HttpServletResponse response) throws Exception {
response.setDateHeader("Expires", 0);
response.setHeader("Cache-Control", "no-store, no-cache, must-revalidate");
response.addHeader("Cache-Control", "post-check=0, pre-check=0");
response.setHeader("Pragma", "no-cache");
response.setContentType("image/jpeg");
OutputStream os = response.getOutputStream();
//返回验证码和图片的map
Map<String,Object> map = Captcha.getImageCode(86, 37, 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"), "jpg", os);
} catch (IOException e) {
return "";
} finally {
if (os != null) {
os.flush();
os.close();
}
}
return null;
}
}
2.验证前端输入的验证码API：
/**
* Author: SamGroves
*
* Description: 获得前端输入验证码的验证
*
* Date: 2017/8/26
*/
@Controller
@RequestMapping("/api")
public class VerifyController extends BaseController{
/**
* @param checkCode 前端用户输入返回的验证码
* 参数若需要，自行添加
*/
@RequestMapping(value = "/verify")
@ResponseBody
public String checkcode(HttpServletRequest request,
HttpSession session,
String checkCode) throws Exception {
// 获得验证码对象
Object cko = session.getAttribute("simpleCaptcha");
if (cko == null) {
request.setAttribute("errorMsg", "请输入验证码！");
return "请输入验证码！";
}
String captcha = cko.toString();
// 判断验证码输入是否正确
if (StringUtils.isEmpty(checkCode) || captcha == null || !(checkCode.equalsIgnoreCase(captcha))) {
request.setAttribute("errorMsg", "验证码错误！");
return "验证码错误，请重新输入！";
// 验证码有效时长为1分钟
Date now = new Date();
Long codeTime = Long.valueOf(session.getAttribute("codeTime") + "");
} else if ((now.getTime() - codeTime) / 1000 / 60 > 1) {
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 {
// 在这里可以处理自己需要的事务，比如验证登陆等
return "验证通过！";
}
}
}
3.前两个接口类中所包含的方法的工具类：Captcha.java
/**
* Author: SamGroves
*
* Description: 验证码生成器
*
* Date: 2017/8/29
*/
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 Captcha {
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);
// 设置随便码在背景图图片上的位置
g.drawString(str, 13 * i + 20, 25);
}
// 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);
}
}
结语：前端显示图片验证码并能点击图片重新请求方法：http://127.0.0.1:8080/api//captcha + new date();
原文作者：@疯狂的米老鼠(已授权)
文章地址：http://www.jianshu.com/p/29f005992527