package com.dsh.account.service;
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import com.dsh.account.model.ImageCaptchaVo;
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import com.dsh.account.util.RedisUtil;
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import org.springframework.beans.factory.annotation.Autowired;
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import org.springframework.beans.factory.annotation.Value;
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import org.springframework.stereotype.Service;
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import javax.imageio.ImageIO;
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import java.awt.Color;
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import java.awt.Font;
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import java.awt.Graphics2D;
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import java.awt.RenderingHints;
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import java.awt.geom.AffineTransform;
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import java.awt.image.BufferedImage;
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import java.io.ByteArrayOutputStream;
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import java.io.IOException;
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import java.security.SecureRandom;
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import java.util.Base64;
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import java.util.Locale;
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import java.util.UUID;
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/**
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* 短信发送前置图形验证码服务。
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*/
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@Service
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public class ImageCaptchaService {
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private static final String CAPTCHA_KEY_PREFIX = "security:sms:image-captcha:";
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private static final String CREATE_LIMIT_KEY_PREFIX = "security:sms:image-captcha:create:";
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private static final char[] CAPTCHA_CHARS = "23456789ABCDEFGHJKLMNPQRSTUVWXYZ".toCharArray();
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private static final int CAPTCHA_LENGTH = 4;
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private static final int IMAGE_WIDTH = 120;
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private static final int IMAGE_HEIGHT = 44;
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private final SecureRandom secureRandom = new SecureRandom();
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@Autowired
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private RedisUtil redisUtil;
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@Value("${security.sms.image-captcha-expire-seconds:120}")
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private int expireSeconds;
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@Value("${security.sms.image-captcha-max-per-minute:10}")
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private int maxPerMinute;
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/**
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* 创建与手机号、短信用途绑定的图形验证码。
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*
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* @return 达到生成频率上限时返回null
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*/
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public ImageCaptchaVo create(String phone, Integer type, String clientIp) throws IOException {
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if (!redisUtil.tryAcquireFixedWindow(
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CREATE_LIMIT_KEY_PREFIX + clientIp,
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maxPerMinute,
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60)) {
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return null;
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}
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String captchaId = UUID.randomUUID().toString().replace("-", "");
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String captchaCode = randomCode();
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redisUtil.setStrValue(
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CAPTCHA_KEY_PREFIX + captchaId,
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captchaValue(phone, type, captchaCode),
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expireSeconds
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);
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return new ImageCaptchaVo(captchaId, renderImage(captchaCode), expireSeconds);
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}
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/**
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* 原子校验并删除验证码。无论输入是否正确，每个验证码都只能提交一次。
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*/
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public boolean verifyAndConsume(String captchaId, String captchaCode, String phone, Integer type) {
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if (captchaId == null || captchaCode == null) {
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return false;
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}
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String normalizedId = captchaId.trim().toLowerCase(Locale.ROOT);
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String normalizedCode = captchaCode.trim().toUpperCase(Locale.ROOT);
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if (!normalizedId.matches("[0-9a-f]{32}") || !normalizedCode.matches("[0-9A-Z]{4}")) {
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return false;
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}
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return redisUtil.consumeIfEquals(
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CAPTCHA_KEY_PREFIX + normalizedId,
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captchaValue(phone, type, normalizedCode)
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);
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}
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private String randomCode() {
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StringBuilder code = new StringBuilder(CAPTCHA_LENGTH);
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for (int i = 0; i < CAPTCHA_LENGTH; i++) {
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code.append(CAPTCHA_CHARS[secureRandom.nextInt(CAPTCHA_CHARS.length)]);
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}
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return code.toString();
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}
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private String renderImage(String code) throws IOException {
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BufferedImage image = new BufferedImage(IMAGE_WIDTH, IMAGE_HEIGHT, BufferedImage.TYPE_INT_RGB);
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Graphics2D graphics = image.createGraphics();
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try {
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graphics.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
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graphics.setColor(new Color(245, 247, 250));
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graphics.fillRect(0, 0, IMAGE_WIDTH, IMAGE_HEIGHT);
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drawNoise(graphics);
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drawCode(graphics, code);
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} finally {
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graphics.dispose();
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}
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try (ByteArrayOutputStream output = new ByteArrayOutputStream()) {
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ImageIO.write(image, "png", output);
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return "data:image/png;base64," + Base64.getEncoder().encodeToString(output.toByteArray());
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}
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}
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private void drawNoise(Graphics2D graphics) {
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for (int i = 0; i < 7; i++) {
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graphics.setColor(randomColor(150, 210));
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graphics.drawLine(
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secureRandom.nextInt(IMAGE_WIDTH),
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secureRandom.nextInt(IMAGE_HEIGHT),
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secureRandom.nextInt(IMAGE_WIDTH),
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secureRandom.nextInt(IMAGE_HEIGHT)
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);
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}
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for (int i = 0; i < 45; i++) {
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graphics.setColor(randomColor(120, 220));
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graphics.fillOval(secureRandom.nextInt(IMAGE_WIDTH), secureRandom.nextInt(IMAGE_HEIGHT), 2, 2);
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}
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}
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private void drawCode(Graphics2D graphics, String code) {
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graphics.setFont(new Font(Font.SANS_SERIF, Font.BOLD, 27));
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for (int i = 0; i < code.length(); i++) {
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Graphics2D characterGraphics = (Graphics2D) graphics.create();
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try {
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characterGraphics.setColor(randomColor(25, 115));
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double angle = (secureRandom.nextDouble() - 0.5D) * 0.45D;
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int x = 12 + i * 26;
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int y = 31 + secureRandom.nextInt(6) - 3;
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characterGraphics.setTransform(AffineTransform.getRotateInstance(angle, x + 9, y - 10));
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characterGraphics.drawString(String.valueOf(code.charAt(i)), x, y);
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} finally {
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characterGraphics.dispose();
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}
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}
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}
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private Color randomColor(int min, int max) {
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int bound = max - min + 1;
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return new Color(
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min + secureRandom.nextInt(bound),
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min + secureRandom.nextInt(bound),
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min + secureRandom.nextInt(bound)
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);
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}
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private String captchaValue(String phone, Integer type, String code) {
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return phone + ":" + type + ":" + code;
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}
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}
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