重构。

src/main/java/xyz/zhouxy/plusone/commons/util/RandomTools.java

@@ -1,14 +1,29 @@
 package xyz.zhouxy.plusone.commons.util;
 
-import java.security.SecureRandom;
+import java.util.Random;
+import java.util.concurrent.ThreadLocalRandom;
 
 public final class RandomTools {
+
     private RandomTools() {
         throw new IllegalStateException("Utility class");
     }
 
-    public static String secureRandomStr(char[] sourceCharacters, int length) {
-        SecureRandom random = new SecureRandom();
+    public static String randomStr(char[] sourceCharacters, int length) {
+        return randomStr(ThreadLocalRandom.current(), sourceCharacters, length);
+    }
+
+    /**
+     * 使用传入的随机数生成器，生成指定长度的字符串
+     * 
+     * @param random           随机数生成器。根据需要可以传入
+     *                         {@link java.util.concurrent.ThreadLocalRandom}、{@link java.security.SecureRandom}
+     *                         等，不为空
+     * @param sourceCharacters 字符池。字符串的字符将在数组中选，不为空
+     * @param length           字符串长度
+     * @return 随机字符串
+     */
+    public static String randomStr(Random random, char[] sourceCharacters, int length) {
         char[] result = new char[length];
         for (int i = 0; i < length; i++) {
             result[i] = sourceCharacters[random.nextInt(sourceCharacters.length)];