随机数代码优化

panda-code/src/main/java/org/panda/code/uitl/StringUtil.java

@@ -71,11 +71,11 @@ public class StringUtil {
     public static String randomString(int length){
         StringBuffer randomString=new StringBuffer();
         while (length>0){
-            Random random=new Random();
+            ThreadLocalRandom threadLocalRandom = ThreadLocalRandom.current();
-            int ran=random.nextInt(3);
+            int ran=threadLocalRandom.nextInt(3);
             switch (ran){
                 case 0:
-                    randomString.append(random.nextInt(10));
+                    randomString.append(threadLocalRandom.nextInt(10));
                     break;
                 case 1:
                     randomString.append(randomLowerCase());