fix(KaptchaTextCreator): 随机数生成器调整为/dev/urandom非阻塞熵池

Closes #I4E0WL

youlai-gateway/src/main/java/com/youlai/gateway/kaptcha/KaptchaTextCreator.java

@@ -14,7 +14,11 @@ import java.security.SecureRandom;
 public class KaptchaTextCreator extends DefaultTextCreator {
 
     private static final String[] CNUMBERS = "0,1,2,3,4,5,6,7,8,9,10".split(",");
-    private SecureRandom rand = SecureRandom.getInstanceStrong();
+
+    // https://gitee.com/youlaitech/youlai-mall/issues/I4E0WL?from=project-issue
+    // private SecureRandom random = SecureRandom.getInstanceStrong(); // /dev/random 作为熵池，熵越大随机性越好，熵池数量不足就会阻塞线程，适用随机数比较高的请求。
+
+    private SecureRandom random = new SecureRandom(); // /dev/urandom 作为熵池，非阻塞的随机数生成器，重复使用熵池中的数据以产生伪随机数据，不会产生阻塞，适用生成较低强度的伪随机数。
 
     public KaptchaTextCreator() throws NoSuchAlgorithmException {
     }
@@ -22,10 +26,10 @@ public class KaptchaTextCreator extends DefaultTextCreator {
     @Override
     public String getText() {
         Integer result = 0;
-        int x = this.rand.nextInt(10);
-        int y = this.rand.nextInt(10);
+        int x = this.random.nextInt(10);
+        int y = this.random.nextInt(10);
         StringBuilder suChinese = new StringBuilder();
-        int randomoperands = (int) Math.round(rand.nextDouble() * 2);
+        int randomoperands = (int) Math.round(random.nextDouble() * 2);
         if (randomoperands == 0) {
             result = x * y;
             suChinese.append(CNUMBERS[x]);