optimized code.

src/main/java/com/alibaba/fastjson/util/IOUtils.java

@@ -275,36 +275,34 @@ public static void getChars(long i, int index, char[] buf) {
      * backwards from there. Will fail if i == Integer.MIN_VALUE
      */
     public static void getChars(int i, int index, char[] buf) {
-        int q, r;
-        int charPos = index;
+        int q, r, p = index;
         char sign = 0;
 
         if (i < 0) {
             sign = '-';
             i = -i;
         }
 
-        // Generate two digits per iteration
         while (i >= 65536) {
             q = i / 100;
             // really: r = i - (q * 100);
             r = i - ((q << 6) + (q << 5) + (q << 2));
             i = q;
-            buf[--charPos] = DigitOnes[r];
-            buf[--charPos] = DigitTens[r];
+            buf[--p] = DigitOnes[r];
+            buf[--p] = DigitTens[r];
         }
 
         // Fall thru to fast mode for smaller numbers
         // assert(i <= 65536, i);
         for (;;) {
             q = (i * 52429) >>> (16 + 3);
             r = i - ((q << 3) + (q << 1)); // r = i-(q*10) ...
-            buf[--charPos] = digits[r];
+            buf[--p] = digits[r];
             i = q;
             if (i == 0) break;
         }
         if (sign != 0) {
-            buf[--charPos] = sign;
+            buf[--p] = sign;
         }
     }