Java实现校验码校验功能逻辑：
首先前端传入一个时间戳，作为唯一标识，然后后端根据时间戳生成一个验证码的图片响应给前端。代码如下：
首先添加一个生成验证码的工具类：
package com.xiaojukeji.it.common.util;
import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.*;
import java.util.Properties;
import java.util.Random;
/**
* Description: [验证码生成器]
*/
public class CaptchaUtils {
// 图片的宽度。
private int width = 120;
// 图片的高度。
private int height = 40;
// 验证码字符个数
private int codeCount = 4;
// 验证码干扰线数
private int lineCount = 50;
// 验证码
private String code = null;
// 验证码图片Buffer
private BufferedImage buffImg = null;
private char[] codeSequence = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'M', 'N', 'P', 'Q', 'R', 'S',
'T', 'U', 'V', 'W', 'X', 'Y', 'Z', '2', '3', '4', '5', '6', '7', '8', '9' };
// 生成随机数
private Random random = new Random();
public CaptchaUtils() {
this.createCode();
}
/**
*
* @param width
* 图片宽
* @param height
* 图片高
*/
public CaptchaUtils(int width, int height) {
this.width = width;
this.height = height;
this.createCode();
}
/**
*
* @param width
* 图片宽
* @param height
* 图片高
* @param codeCount
* 字符个数
* @param lineCount
* 干扰线条数
*/
public CaptchaUtils(int width, int height, int codeCount, int lineCount) {
this.width = width;
this.height = height;
this.codeCount = codeCount;
this.lineCount = lineCount;
this.createCode();
}
public void createCode() {
int codeX = 0;
int fontHeight = 0;
fontHeight = height - 5;// 字体的高度
codeX = width / (codeCount + 3);// 每个字符的宽度
// 图像buffer
buffImg = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
Graphics2D g = buffImg.createGraphics();
// 将图像填充为白色
g.setColor(Color.WHITE);
g.fillRect(0, 0, width, height);
// 创建字体
ImgFontByte imgFont = new ImgFontByte();
// Font font = imgFont.getFont(fontHeight);
Font font = getFont(fontHeight);
g.setFont(font);
// 绘制干扰线
for (int i = 0; i < lineCount; i++) {
int xs = getRandomNumber(width);
int ys = getRandomNumber(height);
int xe = xs + getRandomNumber(width / 8);
int ye = ys + getRandomNumber(height / 8);
g.setColor(getRandomColor());
g.drawLine(xs, ys, xe, ye);
}
StringBuffer randomCode = new StringBuffer();
// 随机产生验证码字符
for (int i = 0; i < codeCount; i++) {
String strRand = String.valueOf(codeSequence[random.nextInt(codeSequence.length)]);
// 设置字体颜色
g.setColor(getRandomColor());
// 设置字体位置
g.drawString(strRand, (i + 1) * codeX, getRandomNumber(height / 2) + 25);
randomCode.append(strRand);
}
code = randomCode.toString();
}
/** 获取随机颜色 */
private Color getRandomColor() {
int r = getRandomNumber(255);
int g = getRandomNumber(255);
int b = getRandomNumber(255);
return new Color(r, g, b);
}
/** 获取随机数 */
private int getRandomNumber(int number) {
return random.nextInt(number);
}
public void write(String path) throws IOException {
OutputStream sos = new FileOutputStream(path);
this.write(sos);
}
public void write(OutputStream sos) throws IOException {
ImageIO.write(buffImg, "JPEG", sos);
sos.close();
}
public BufferedImage getBuffImg() {
return buffImg;
}
public String getCode() {
return code;
}
/** 字体样式类 */
class ImgFontByte {
public Font getFont(int fontHeight) {
try {
Font baseFont = Font.createFont(Font.TRUETYPE_FONT,
new ByteArrayInputStream(hex2byte(getFontByteStr())));
return baseFont.deriveFont(Font.PLAIN, fontHeight);
} catch (Exception e) {
return new Font("Arial", Font.PLAIN, fontHeight);
}
}
private byte[] hex2byte(String str) {
if (str == null)
return null;
str = str.trim();
int len = str.length();
if (len == 0 || len % 2 == 1)
return null;
byte[] b = new byte[len / 2];
try {
for (int i = 0; i < str.length(); i += 2) {
b[i / 2] = (byte) Integer.decode("0x" + str.substring(i, i + 2)).intValue();
}
return b;
} catch (Exception e) {
return null;
}
}
}
private String getFontByteStr() {
Properties prop = new Properties();
try {
BufferedReader in = new BufferedReader(new FileReader("config.properties"));
prop.load(in);
String property = prop.getProperty("FontByteStr");
in.close();
return property;
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
private Font getFont(int size) {
Random random = new Random();
Font font[] = new Font[2];
//font[0] = new Font("Ravie", Font.PLAIN, size);
font[0] = new Font("Antique Olive Compact", Font.PLAIN, size);
font[1] = new Font("Fixedsys", Font.PLAIN, size);
int nextInt = random.nextInt(2);
System.out.println(nextInt);
return font[nextInt];
}
}
控制类里面添加如下方法，生成验证码并存储到Redis里面(如果项目中没有使用Redis，可以考虑落到数据也行)，并响应给前端：
public void getPin(Long timeStamp, HttpServletRequest request, HttpServletResponse response) {
try {
if (null == timeStamp) {
return;
}
response.setContentType("image/jpeg");
response.setHeader("Pragma", "no-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
CaptchaUtils captcha = new CaptchaUtils(); //生成验证码
//存入到redis。时间戳，验证码，标识
redisDB.setAndExpire(timeStamp.toString(), captcha.getCode(), Const.REDIS_USER_CODE);
captcha.write(response.getOutputStream());
} catch (Exception e) {
log.error("获取验证码异常！");
exceptionService.handler("获取验证码异常", e, request);
}
}
前端再次将验证码提交到后台，我们从Redis中取出来进行比较验证。
// redis中查找验证码，图片验证码
String redisImgCode = redisDB.get(person.getImgTimeStamp());
// redis中获取不到验证码, 验证码过期
if (StringUtils.isBlank(redisImgCode)) {
return AjaxInfo.renderError(AjaxInfo.CODE_PIN_OVERDUE);
}
// 判断图片验证码是否正确
if (StringUtils.isBlank(person.getImgCode()) || !redisImgCode.toLowerCase().equalsIgnoreCase(person.getImgCode().toLowerCase())) {
redisDB.del(person.getImgCode());
return AjaxInfo.renderError(AjaxInfo.CODE_PIN_ERROR);
}